# Generator Oscilloscope Waveform Measurements



## drmerdp

How dirty is your generators electricity? Most people haven’t a clue. Others see their voltage and frequency to be on point and assume their generator is great. The truth is not all generators produce clean power, and the ones that advertise super low THD might not be up to snuff.

I have scope readings I’ve taken on various generators. Enjoy

THD = Total Harmonic Distortion


GRID/UTILITY POWER 






















Honda Eu7000is Advertised at less then 3% THD. Loaded or unloaded it’s the same..... perfect. I think it’s actually cleaner then my grid reading.






















Honda EB6500x No advertised THD 


No load




















4600watts load























Kohler 20Kw standby generator. Advertised at less then 5%THD

Under approx 1/4 load.


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## tabora

PowerMate PM0126000 No Load










PowerMate PM0126000 Half Load


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## iowagold

yup the honda eu7000is wave looks like the ones we have as well.

pretty lumpy on the rest of the waveforms lol...

the time factor lumps hummm.

I wonder what fq's on the spurs are all in there on the lumpy wave forms??

an inverter gen is like a motor drive so everything "sings"
listen to a honda gen when it shuts down.
you can hear the pulse!!

I was able to get them to change out the pole transformer here 10 years back..
it was horrible on the sag and time..
they put in a data logger for a week to record the waveform
and did another a couple of houses down from me on a different pig.

they did a good job finding the issue.
the new pig so far has done well

the old pig was super noisy when you used an am radio by it.
arc inside the pig some where.


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## Melson

Ah, nice posting, drmerdp, especially for folks not able to visualize what a distorted waveform looks like.

The surprising truth, if you'll allow me to steal the phrase, is most electrical equipment will tolerate a horrible looking sine wave. For quite a while, too. 
I know what you're thinking, 'long term stress & unpredictable point failure'. And you'd be right. Still, over / under voltage is more dangerous for quickly taking something out, overvoltage being the major villain. And frequency, of course, will cause strange effects.

By the way, @tabora, I sold my Dranitz gear on eBay when I retired. Sweet stuff! I sure wish I kept it; it was the best monitoring & recording! Better than anything Fluke, on par with Tektronics. Can I borrow it and maybe promise to give it back? <GRIN>


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## ToolLover

I am being re-educated!
I used large oscilloscopes mounted on a push cart when I was a technician in industry.
A friend of mine was a TV repairman and he had two scopes.
A few years ago he asked me if I wanted one of the scopes.
I declined his offer.
At the time I had no need for one as being retired I did not need it.
He sold the entire tube inventory, the scopes and meters to a guy in South Carolina.
Now, I realize that I should have taken him up on his offer.
I am considering buying a scope just to satisfy my curiosity after reading the above post.
My curiosity is running rampant!


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## Melson

@toolover, one of my fluke meters is the 867b, a dvom with 1mhz oscope function. It's OK, not particularly fast but the lcd display is nice, it has auto adjust, is quite good enough for 60hz sine.
I paid $1k new, year 1998, you can now get them used for low 200's, maybe less.
Just one option for you if you also need a multimeter.


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## ToolLover

Melson said:


> @toolover, one of my fluke meters is the 867b, a dvom with 1mhz oscope function. It's OK, not particularly fast but the lcd display is nice, it has auto adjust, is quite good enough for 60hz sine.
> I paid $1 k new, year 1998, you can now get them used for low 200's, maybe less.
> Just one option for you if you also need a multi meter.


Melson, I have two Flukes and a new SouthWire meter.
I have to admit, the post has got me very curious about frequency problems.
Just that I am not sure that I am curious enough to invest $225 in a Hantek scope from Amazon


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## KRE

I use a Berger or Granite's power analyzer depending task an can tell you there are very few mfg's that will meet a TRUE 5% THD test. Even some of the major mfgs who deal in much bigger iron have issues meeting that spec, even though 5 is printed on their spec charts. One day the industry will clamp down, however as long as price point is driving the market the lies will continue.


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## tabora

Melson said:


> By the way, @tabora , I sold my Dranitz gear on eBay when I retired. Sweet stuff! I sure wish I kept it; it was the best monitoring & recording! Better than anything Fluke, on par with Tektronics. Can I borrow it and maybe promise to give it back? <GRIN>


Would you believe that I bought mine on eBay for $29.99 plus $19 shipping? I purchased a full cable set piecemeal VERY inexpensively, and it uses the same paper spools as my credit card machine.


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## Melson

tabora said:


> _Would you believe that I bought mine on eBay for $29.99 plus $19 shipping? I purchased a full cable set piecemeal VERY inexpensively, and it uses the same paper spools as my credit card machine_.


Actually, I AM a bit surprised. What a steal! 
Whoever sold it either didn't know how good even the basic and ancient Dranetz are.. or didn't care. I paid $12 *thousand* (thousand!) for a new three phase jobber back in the late 80's. 
How are the batteries doing?


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## tabora

Melson said:


> Actually, I AM a bit surprised. What a steal!
> Whoever sold it either didn't know how good even the basic and ancient Dranetz are.. or didn't care. I paid $12 *thousand* (thousand!) for a new three phase jobber back in the late 80's.
> How are the batteries doing?


 Yup, the full retail on my PP1 unit (which can also do 3-phase - every power permutation up to 600V) with all the accessories was about $12K around the turn of the century... It had a dead battery and about every error message showing on boot; however, based on prior experience I knew it probably just needed to be reset and have the simple recalibrations done. So, yeah, practically grand theft by auction! My old basic Dranetz cost over $8K back in the 1980s.

The NiCD 12V 10cell battery pack in the PP1 was dead, so I purchased a same-size NiMH 12V pack and external charging unit for it (at $25 it was about 20% of the cost of the replacement Dranetz NiCD pack).


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## ToolLover

Well, this post really got my curiosity up. 
I went on Ebay and looked for a Techtronic dual trace scope as I used one many years in my work.
Well as luck would have it there was a used one up for bid.
Starting bid was $80 so I bid that amount plus $20 delivery.
I got busy the next day and the biding ended.
Well, I guess you know I missed it.
The scope sold for $135 and I was really let down that I had not paid better attention.
Now my curiosity is still hanging in there too.


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## iowagold

check out this auction for scope
Tektronix 2236 100MHz Dual Trace Oscilloscope
https://www.ebay.com/itm/Tektronix-2236-100MHz-Dual-Trace-Oscilloscope-30-Day-Warranty/293474491464?


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## ToolLover

@iowagold: I spent Saturday evening going thru the posted Techtronic scopes. 
I got frustrated and a little confused.
Many were obviously used and used and used to the point that I was leery of biding.
Too much use and the tube gets cloudy and eventually stops performing.
I just gave up and let it go.
I did however bid on the one you pointed to. 
I am not really wanting to win a bid unless I can get one on the low end.
I prefer the Techtronic over the new hand held units.


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## Melson

ToolLover, if your needs are modest there are cordless digital Fluke models that are quite good enough, and no worries about gnd loops. Actually the 1mhz cordless fluke "Scopemeter" I kept is great for general purposes. So maybe cast a slightly broader net?


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## iowagold

@ToolLover
yea there used to be a place in desmoines iowa that re mfg the crt.
cool for good equipment!!
new spray inside and new gun if it needed it for less than 200 bucks!!
nice for expensive test gear!!

I like the old crt trace... unless you have a high resolution tft display..

I have been looking at Bluetooth scopes that will work with ipad pro..
wireless so no chance on frying the $1000.00 pad..

the classic analog test gear works for me..
faster than all the setup menus!!
lol!


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## Old man here

Ok, I'll play.
Using a 120V to 12V isolation transformer to take the readings.
Generac GP 15000.
1500 watt load









3000 Watt load









Utility Power


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## iowagold

wow top 2 wave forms look like crap!
bottom one looks ok.
as long at the time factor was good (60hz)


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## tabora

iowagold said:


> wow top 2 wave forms look like crap!


Those actually look pretty good for a conventional construction generator...


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## Old man here

It is actually used to run my "all electric" house during power outages when I need central air or heat.
I live in a rural area and do not have NG or propane available.
I have a 2 1/2 ton heat pump to supply heat and air.
The GP15000E handles the job well. I have a 50 AMP inlet connected to my breaker box with an interlock switch.
Nothing complains {nor my wife} while on the generator. Just have to shed loads at times as needed.
Also have two UPS units that are set to "low sensitivity" that work without any complaints or switching.
I agree, it is not an inverter quality sine wave and I don't have the equipment required to measure the THD but it does put out very stable voltage and HZ at all loads. Those, I watch closely.
During mild weather I use a Champion Power Equipment 100519 6250-Watt Open Frame Inverter generator to save fuel. The GP15000E is a gas hog. Many hours on it and have not had an issue.


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## jeb

Adding to the waveforms so they are on this main thread.
Here is a Generac Ultrasource 15000. Sampled through a 12V transformer. 

This is at 6000watts (3K per phase) load.









There is some frequency drift. If I turn on persistence (digital oscope), you'll see there is some frequency drift.









Here is at 10KW load (5KW per phase):










I don't have a method to measure THD...but Generac did finally admit that its < 20%.




If anyone has the output of a CAT RP12000E or a Westinghouse WGEN12000, please post. I'd love to see what that waveform looks like as I'm thinking about purchasing one of these.


-J


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## speedy2019

my 1800watt UPS has a THD of 5% or lower,,,but I have no idea of the THD on my 2800watt non-inverter generator is, but Im guessing its quite shockingly bad.


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## Old man here

jeb said:


> Adding to the waveforms so they are on this main thread.
> Here is a Generac Ultrasource 15000. Sampled through a 12V transformer.
> 
> There is some frequency drift. If I turn on persistence (digital oscope), you'll see there is some frequency drift.
> View attachment 8810
> 
> 
> I don't have a method to measure THD...but Generac did finally admit that its < 20%.
> 
> 
> 
> 
> If anyone has the output of a CAT RP12000E or a Westinghouse WGEN12000, please post. I'd love to see what that waveform looks like as I'm thinking about purchasing one of these.
> 
> 
> -J


Turn on persistence with your utility power, is there any drift over time?


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## jeb

Old man here said:


> Turn on persistence with your utility power, is there any drift over time?


Good question. I've been on generator power for 6 days since our Winter storm...so will do that when we finally get power back


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## Old man here

jeb said:


> Good question. I've been on generator power for 6 days since our Winter storm...so will do that when we finally get power back


Sorry to hear that, hope you are doing ok and keeping warm enough.


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## jeb

We are doing good. Feel fortunate that we have multiple backups (including wood stove and gas place). Feel bad for folks that are not as prepared.


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## Old man here

jeb said:


> We are doing good. Feel fortunate that we have multiple backups (including wood stove and gas place). Feel bad for folks that are not as prepared.


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## Old man here

jeb said:


> We are doing good. Feel fortunate that we have multiple backups (including wood stove and gas place). Feel bad for folks that are not as prepared.


If it warms up some tomorrow, I'll set up my scope and measure the frequency drift on utility power. It's a digital scope as well.


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## Old man here

jeb said:


> Adding to the waveforms so they are on this main thread.
> Here is a Generac Ultrasource 15000. Sampled through a 12V transformer.
> 
> This is at 6000watts (3K per phase) load.
> View attachment 8808
> 
> 
> There is some frequency drift. If I turn on persistence (digital oscope), you'll see there is some frequency drift.
> View attachment 8810
> 
> 
> Here is at 10KW load (5KW per phase):
> View attachment 8809
> 
> 
> 
> I don't have a method to measure THD...but Generac did finally admit that its < 20%.
> 
> 
> 
> 
> If anyone has the output of a CAT RP12000E or a Westinghouse WGEN12000, please post. I'd love to see what that waveform looks like as I'm thinking about purchasing one of these.
> 
> 
> -J


Jeb, Here is my utility power:
Normal








Persistence:


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## jeb

Here is my utility power by comparison (finally came back on after 6 days 😃)










Here is the drift of my utility power:


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## Old man here

jeb said:


> Here is my utility power by comparison (finally came back on after 6 days 😃)
> View attachment 8824
> 
> 
> 
> Here is the drift of my utility power:
> View attachment 8825


What we are seeing here is not drift but voltage fluctuation. Most notable in my examples.
Due to two electric space heaters on the circuit I was recording, the voltage varied from 118V to 124V as the heaters cycled on and off.
Thanks for posting the follow up.
Glad you are back on the grid!


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## Old man here

I received my new Fluke 345 Power Quality Clamp Meter - Electronic Power Meter today. Let the fun begin.
No more guessing what the THD is, and what effects the output THD of my generators.
I have other uses for it as well. The Science lab is open.


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## Airstreamer67

Man o Man, I feel like the first day in chemistry class with all those test tubes lined up in a row. Hope you have fun 

Keep us up with your findings, please.


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## Old man here

Airstreamer67 said:


> Man o Man, I feel like the first day in chemistry class with all those test tubes lined up in a row. Hope you have fun
> 
> Keep us up with your findings, please.


Will do.


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## iowagold

LOL!
just like christmas over there!
"look out world he has a meter!"
lol!
let me know when you get your first fluke scope meter.


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## Old man here

iowagold said:


> LOL!
> just like christmas over there!
> "look out world he has a meter!"
> lol!
> let me know when you get your first fluke scope meter.


Got it yesterday. Look up what it is.


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## iowagold

yup for a small unit it looks like a good one.
we have the larger 4 line version in the lab.
4 clamps and does digital data log.
cool for 3 phase with ground.
you can see all of it at the same time span that way.

yup all that vector stuff is what you need to look at power and phase alignment.
and the better the resolution the better the data...

good job on the good meter choice!
lol
you will have to go back to school just to learn how to fire it up!!
LOL!
did it have blue tooth yet?
i did not check on that...
fluke they are adding blue tooth to some of the new meters now so you can see them in data view or lab view for industrial.
and doing wifi as well.


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## iowagold

oh that brings up a question for you!
what band selectivity does the band scope have??
can you narrow that down??
just thinking digital trash these days from cell towers harmonics..
and they feed digital control signals down the power lines now...
horrible hash!

the meters are only as good as the pickup as well..


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## Bulldogger

Bob S pointed out that a Powerhorse generator I have on order has a stated frequency range of frequency ranges from 56.5 to 63.3 hertz per the manual. Powerhorse claims 5% distortion. Does frequency drift have a bearing on distortion? Even if the distortion is actually only is 5%, does having a such a frequency range make it meaningless for use with sensitive electronics as it would still be unsafe?


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## Old man here

As promised results from my Generac GP15000E with my Fluke 345 Power Quality Clamp Meter.
Will do the Champion Inverter later.
No load:
















House Load with Heat Pump, TV's and all LED lights turned on.








Sine wave output with house load.


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## Airstreamer67

Wow. That is cool.

When manufacturers put out their THD data, it may be based on a no-load condition. If so, is that a valid value to believe if a load causes three times the distortion?

After all, a high THD wouldn't hurt anything if nothing is on the genset, and a low THD doesn't help anything if it's only when there is no load.

In any case, I don't remember seeing equipment being reported as damaged by gensets with high THDs. I have seen reports that some appliance may not run on a particular genset, but that doesn't mean it was damaged in the trying. If some vital appliance doesn't run, then either get another genset or another appliance.

Interesting data. Thanks!


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## Old man here

Airstreamer67 said:


> Wow. That is cool.
> 
> When manufacturers put out their THD data, it may be based on a no-load condition. If so, is that a valid value to believe if a load causes three times the distortion?
> 
> After all, a high THD wouldn't hurt anything if nothing is on the genset, and a low THD doesn't help anything if it's only when there is no load.
> 
> In any case, I don't remember seeing equipment being reported as damaged by gensets with high THDs. I have seen reports that some appliance may not run on a particular genset, but that doesn't mean it was damaged in the trying. If some vital appliance doesn't run, then either get another genset or another appliance.
> 
> Interesting data. Thanks!


If you guys think UPS systems deliver clean power, this is scary!
I know that the double conversion UPS units are top of the line but, so many of us out there own the Line Interactive UPS units.
I have two, one is a CyberPower 1500VA AVR, the other is an APC 1500 Back-UPS XS.
I will test the APC later.
This test was performed using a Fluke 345 Power Quality Clamp Meter.
Testing was done with three laptops connected and the power cord pulled from the outlet.


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## Airstreamer67

That looks like the patterns I've seen for non-pure sine wave inverters popular with campers. They seem to operate many things without problems. I've run small refrigerators and such with them. Some things that won't work with them are at least some microwaves and, of all things, electric blankets. But this type inverter is popular because they cost a fraction of the pure sine wave units.

Your new Fluke is going to give us a lot of interesting information if you keep this up. I'm wondering how those inverter gensets fare on the screen.

Thanks!


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## Old man here

Airstreamer67 said:


> That looks like the patterns I've seen for non-pure sine wave inverters popular with campers. They seem to operate many things without problems. I've run small refrigerators and such with them. Some things that won't work with them are at least some microwaves and, of all things, electric blankets. But this type inverter is popular because they cost a fraction of the pure sine wave units.
> 
> Your new Fluke is going to give us a lot of interesting information if you keep this up. I'm wondering how those inverter gensets fare on the screen.
> 
> Thanks!


Thanks, I have a lot of uses for the new meter.
I will be testing the Champion 6250-Watt Open Frame Inverter generator once the weather clears up again.
The line interactive UPS units have their place. I wish I had a double conversion pure sine wave UPS to test.
It will be interesting to see How the APC does, It only has a modem, router and a 2-bay NAS connected to it.
I may also test the CyberPower with no laptops connected, two connected and one connected to see how that influences the THD output.


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## tvl

Disregard


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## Airstreamer67

Loads placed on the generator can profoundly impact power quality on the system in various ways, some good and some bad: resistive, inductive, reductive, capacitive, whatever.

Some loads can be like the drunk uncle at a Christmas party; others like Mother Theresa at a christening.

So, are we being too anal about surfing a perfect sine wave from an expensive inverter genset when some loads can put sharks in the water?
Maybe the new Fluke can tell us.


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## Old man here

Results from my APC 1500 Back-UPS XS with one NAS, one modem, and one Router connected on battery power.


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## Old man here

Airstreamer67 said:


> Loads placed on the generator can profoundly impact power quality on the system in various ways, some good and some bad: resistive, inductive, reductive, capacitive, whatever.
> 
> Some loads can be like the drunk uncle at a Christmas party; others like Mother Theresa at a christening.
> 
> So, are we being too anal about surfing a perfect sine wave from an expensive inverter genset when some loads can put sharks in the water?
> Maybe the new Fluke can tell us.


I have many tests planned for resistive, inductive, reductive, capacitive as you said. All I need is time.
I will post results if found to be of interest.


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## LaSwamp

THD in excess of 50%? That's rather dreadful. I wouldn't want to run anything on that kind of power.


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## Old man here

LaSwamp said:


> THD in excess of 50%? That's rather dreadful. I wouldn't want to run anything on that kind of power.


It is unfortunate that these companies market the UPS units such as these for keeping your computers and such on line during a power outage. 
I've been using them for years with no adverse effects though. My testing was an eye opener though!


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## Airstreamer67

Your results seem to verify the assertions made by this poster or source, the origin of which I've lost in my chaotic world somewhere:

"Now, lets talk about UPS (uninterrupted power supply). The majority of UPSs, especially ones that cost under $20,000, simply represent a large non-linear power supply to their AC source. Just like the SMPSs, they wreak havoc on the AC power quality of their source. Someone mentioned 'double-conversion' UPS. Nice; but clueless. (Sorry.) The output of a double-conversion UPS is almost always much, much poorer than the AC source sine wave entering it. They use PWM (pulse width modulation) or some other method to convert the DC back into AC, resulting in one of the most choppy 'sine waves' one could ever see. Yeah, they ensure the voltage doesn't drop when their input does, and they filter transients, but that's about all they do. Aside from that, the power quality of their output is horrible. Again, anything under $20,000 and the output is going to look more like a square wave than anything. Add capacitance of the circuit, and its much poorer than that. The majority of low-cost UPS equipment (under $20k) chop their output into three squarish-looking chunks each half-cycle. You have to pay big bucks to get a 12- or 18-pulse UPS with adequate input and output filtering. But all this is not a problem, because 99% of the time, the SMPS equipment that is connected to UPS systems doesn't care one bit."

Addendum: SMPS = switch mode power supply, like what is found with laptops, etc.


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## Airstreamer67

Old man here said:


> I have many tests planned for resistive, inductive, reductive, capacitive as you said. All I need is time.
> I will post results if found to be of interest.


Oh yeah, I'm sure there is interest in these tests! After all, the intensive discussions that are taking place about inverter gensets being necessary for today's "sensitive" electronics are of great interest to many. 

Personally, I haven't seen such a need yet, since all of my old gensets are non-inverter types and haven't hurt anything yet, I don't think :-/

So, what can be revealed by Mr Fluke  through your tests has to be of interest to many.

Thanks for your contributions to us Gen-Heads!


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## Old man here

Airstreamer67 said:


> Your results seem to verify the assertions made by this poster or source, the origin of which I've lost in my chaotic world somewhere:
> 
> "Now, lets talk about UPS (uninterrupted power supply). The majority of UPSs, especially ones that cost under $20,000, simply represent a large non-linear power supply to their AC source. Just like the SMPSs, they wreak havoc on the AC power quality of their source. Someone mentioned 'double-conversion' UPS. Nice; but clueless. (Sorry.) The output of a double-conversion UPS is almost always much, much poorer than the AC source sine wave entering it. They use PWM (pulse width modulation) or some other method to convert the DC back into AC, resulting in one of the most choppy 'sine waves' one could ever see. Yeah, they ensure the voltage doesn't drop when their input does, and they filter transients, but that's about all they do. Aside from that, the power quality of their output is horrible. Again, anything under $20,000 and the output is going to look more like a square wave than anything. Add capacitance of the circuit, and its much poorer than that. The majority of low-cost UPS equipment (under $20k) chop their output into three squarish-looking chunks each half-cycle. You have to pay big bucks to get a 12- or 18-pulse UPS with adequate input and output filtering. But all this is not a problem, because 99% of the time, the SMPS equipment that is connected to UPS systems doesn't care one bit."
> 
> Addendum: SMPS = switch mode power supply, like what is found with laptops, etc.


Correct, Generac recommends sizing your generator to provide 5Kw for every 1Kw of 'double-conversion' UPS systems due to the noise they produce back to the generator.


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## Airstreamer67

It's really interesting to see:

---the rough, square-wave pattern that the battery-powered UPS equipment is providing to the device it is protecting and servicing during power outages without the aid of an auxiliary generator;

---and then the "noise" being created for the generator and its serviced circuits when the UPS is in standby mode.

You'd never know all that is going on without seeing it on the Fluke meter and other such devices.

And those huge THD numbers. Say it ain't so, Mac.

But, on the other hand, there are no widespread reports of things being damaged by such UPS equipment or from similar devices like non-pure sine wave inverters that are very commonly used by many folks out there.

So, are we worrying too much about high THDs from non-inverter conventional generators...the ones that have been carrying the load all these many years? Or, are we so fully into the Brave New World where all the new-and-improved controlled-by-a-silicon-board equipment is so sensitive that we must provide them power from a generator that is itself controlled-by-a-silicon-board?

Interesting. Belly, Belly Interesting.


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## LaSwamp

I think most people use frame generators with no idea how much noise they produce, as OMH had said a few days ago. I have heard stories of people who have had issues after using non-inverter generators for a long-ish time. But that seems to be kinda rare. As an example, I have a bowling teammate who has a Predator 7K watt non-inverter that he can connect to his breaker box. He recently used it for about 4 days when we had a big outage due to a winter storm. He ran everything off of it. Fridges, TVs, freezers, the whole shebang. He told me everything worked fine, no issues whatsoever. There were a few items too big to run on it, but otherwise, nothing seemed to be the worse for wear. 

So, I don't know. I'm sure the Predator power wasn't terribly clean given it was your typical frame genset. But it didn't cause any issues for him. Still, I feel better using inverters.


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## Old man here

Champion 100519 6250-Watt Open Frame Inverter sinewave and THD results here:








New Champion Hybrid Inverters


You got my attention when you said the 100519 had a clean sinewave... may I ask how you know? (old man here too... been repairing electronics since my pre-teen years back in the late '60's... later moved to EE, but still big DIYer) Looking for help getting the 100519 Inverter module to function...




www.powerequipmentforum.com


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## mtucker

I tried out a few different AC sources last weekend. 

4375W/3500W Predator traditional generator, 1000W load, sinewave









4375W/3500W Predator traditional generator, 1000W load, THD









2500W/1850W Champion model 100899 (dual fuel) inverter generator, 1000W load, sinewave









2500W/1850W Champion 100899 (dual fuel) inverter generator, 1000W load,THD









I also measured my home power. 
Sinewave. You can see the rounding off of the sinewave from power supplies that only pull power off during the peaks. 









THD was 2.4%


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## jeb

mtucker said:


> I tried out a few different AC sources last weekend.
> 
> 4375W/3500W Predator traditional generator, 1000W load, sinewave
> View attachment 9447
> 
> 
> 4375W/3500W Predator traditional generator, 1000W load, THD
> View attachment 9448
> 
> 
> 2500W/1850W Champion model 100899 inverter generator, 1000W load, sinewave
> View attachment 9449
> 
> 
> 2500W/1850W Champion 100899 inverter generator, 1000W load,THD
> View attachment 9450
> 
> 
> I also measured my home power.
> Sinewave. You can see the rounding off of the sinewave from power supplies that only pull power off during the peaks.
> View attachment 9451
> 
> 
> THD was 2.4%



Thanks for posting this. This is extremely useful information with different gensets.


----------



## mtucker

Pulsar 2200/1800W Dual Fuel Inverter Generator Model PG2200BiS, 1000W load, sinewave










Pulsar 2200/1800W Dual Fuel Inverter Generator Model PG2200BiS, 1000W load, THD


----------



## LaSwamp

I've been looking at scopes for a while. There seems to be a big gap between the ultra cheap ones and the quality ones. I don't want to spend a fortune on one since I will likely rarely use it, but I also don't want to buy something disposable. If I get one, I'll scope my generators and post the results here.


----------



## speedy2019

Old man here said:


> If you guys think UPS systems deliver clean power, this is scary!
> I know that the double conversion UPS units are top of the line but, so many of us out there own the Line Interactive UPS units.
> I have two, one is a CyberPower 1500VA AVR, the other is an APC 1500 Back-UPS XS.
> I will test the APC later.


I would hope my £350 Powerwalker 2000VA/1800WATT Online UPS was half decent.. VFI 2000 TG


----------



## LaSwamp

speedy2019 said:


> I would hope my £350 Powerwalker 2000VA/1800WATT Online UPS was half decent.. VFI 2000 TG


I have a TrippLite 1500 UPS, but I'd bet the battery power output looks like a cactus plant.


----------



## Old man here

speedy2019 said:


> I would hope my £350 Powerwalker 2000VA/1800WATT Online UPS was half decent.. VFI 2000 TG


Look at the specs, Pure Sine Wave and THD 5% or less. Looks like a winner to me.


----------



## speedy2019

Old man here said:


> Look at the specs, Pure Sine Wave and THD 5% or less. Looks like a winner to me.


A halogen bulb flickers on my non-inverter generator but runs fine on my UPS. I run my UPS on my generator when I have a powercut, as I have my whole main room connected to the UPS


----------



## iowagold

halogen has horrible effects on power....
switch over to led bulbs asap.
way less power consumed..


----------



## iowagold

LaSwamp said:


> I've been looking at scopes for a while. There seems to be a big gap between the ultra cheap ones and the quality ones. I don't want to spend a fortune on one since I will likely rarely use it, but I also don't want to buy something disposable. If I get one, I'll scope my generators and post the results here.


i hear you la on the scope!
yea.... hard to find a good scope on the cheap...
a classic scope works well...
modern units for looking at power that fluke unit works.
pricey but they hold value!
pm if you need scope links!


----------



## LaSwamp

iowagold said:


> i hear you la on the scope!
> yea.... hard to find a good scope on the cheap...
> a classic scope works well...
> modern units for looking at power that fluke unit works.
> pricey but they hold value!
> pm if you need scope links!


There seems to be some nice scopes in the $250-$300 range. Rigol, Siglent, Hamtec, and Auroland seem to be the brands on Amazon in that price range. Anyone know if those are good? I'd love a Fluke, but given that I will rarely use the scope much, I can't justify several thousand dollars for one. I really need something I can use to see the waveforms on my generators, especially the Wen that's throwing some weird Hz noise. I'd borrow one if I could, but no one I know seems to have one handy.


----------



## mtucker

LaSwamp said:


> There seems to be some nice scopes in the $250-$300 range. Rigol, Siglent, Hamtec, and Auroland seem to be the brands on Amazon in that price range. Anyone know if those are good? ....................


 Rigol is a lot of bang for the buck. My work tends to buy Rigol scopes for the production area where they just need to view a waveform and take a measurement (VS big bucks for Tektronix or LeCroy scopes for enginerring). I have used a few of them (Rigol scopes) and they seem fine.


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## LaSwamp

mtucker said:


> Rigol is a lot of bang for the buck. My work tends to buy Rigol scopes for the production area where they just need to view a waveform and take a measurement (VS big bucks for Tektronix or LeCroy scopes for enginerring). I have used a few of them (Rigol scopes) and they seem fine.


Tektronix units are very nice, but spendy. I like the Rigol stuff. But all of them in that price range look almost exactly alike. It makes me wonder if they are all made by the same company and branded accordingly.


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## iowagold

Siglent is ok


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## LaSwamp

The base model Rigol is $279. If I buy it off of Amazon, they are going to charge me tax on it. It looks like I can buy from Rigol direct with no sales tax, although I don't know if the probes come with the purchase if you buy it direct.


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## LaSwamp

Okay, I finally did it. I ordered a scope. As it turned out, Amazon has a good sale going on a few units. I decided on this one: Link

It's a Hanmatek DOS1102. It looks like a Rigol/Siglent clone. It seems to get mostly positive reviews. It's normally around $235, but with Prime Day and a discount, I got it for $180. It seems like a pretty good deal for a scope. As soon as I get it, I'll post waveforms for the generators I have. As I mentioned before, I'm really curious to see what the Wen signal looks like.


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## LaSwamp

My scope came in today!

Now I have to figure out how to use it. I tried to take a reading off of house power but I didn't get a reading that made sense. I must be doing it wrong.


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## iowagold

lol that is 1/2 the battle getting them out of the box!
then making sure they work right!

try reading a gen set.

years back we ran in to a HP unit that would not read the same line power they were powered from.

you had to use an isolation transformer for the ac power line.


----------



## LaSwamp

I feel like I'm learning to fly the space shuttle. But I'm making some headway. I checked the calibration on the probes. How does the probes take the reading? Do I just place one of the probes in the outlet? Do both probes need to be used or just one?


----------



## drmerdp

LaSwamp said:


> I feel like I'm learning to fly the space shuttle. But I'm making some headway. I checked the calibration on the probes. How does the probes take the reading? Do I just place one of the probes in the outlet? Do both probes need to be used or just one?


My jinky pocket scope needs both probes, yours likely does as well. Can your scope give a THD reading?


----------



## LaSwamp

drmerdp said:


> My jinky pocket scope needs both probes, yours likely does as well. Can your scope give a THD reading?


I don't think so, but frankly, I don't know. There's a link to it above. I feel like I bought a nuclear reactor. Do you use the probes like you'd use them with a multimeter? 

I now truly feel like a member of the team.


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## LaSwamp

I've watched a few videos in trying to figure out how the scope is supposed to interface with the a/c power source, whether it's one of my gas generators or the wall outlet. One of the videos I saw, the guy was using only one probe/channel to measure the waveform on a Honda generator. I could not tell how he had it connected to the outlet, though. He had some kind of plug he was using that covered how, exactly, it was connected. He did seem to use the probe and the ground. I think my scope is calibrated and ready to go, but I can't figure out how I'm supposed to actually use the probe to connect to the outlets so I can get a reading. How do you guys do it?


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## iowagold

we use isolated probe


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## LaSwamp

iowagold said:


> we use isolated probe


How does it work?


----------



## iowagold

they have a coupling transformer built in for 1to1 , 10 to 1 etc. or what ever the ckt rating is...
we have several so they have different ratios depending on what we are checking.

we have them for both ways so we can look at super small voltages as well as up to 100kv.


----------



## LaSwamp

iowagold said:


> they have a coupling transformer built in for 1to1 , 10 to 1 etc. or what ever the ckt rating is...
> we have several so they have different ratios depending on what we are checking.
> 
> we have them for both ways so we can look at super small voltages as well as up to 100kv.


So I need another part before I can measure waveforms from the generators?


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## iowagold

do what you like....
isolation transformer probes are cheap insurance for the scope.
and for the items you are checking.


----------



## LaSwamp

iowagold said:


> do what you like....
> isolation transformer probes are cheap insurance for the scope.
> and for the items you are checking.


I'm just trying to figure out how the probes interface with the power outlets so they can be measured. It looks like only one probe is needed, but I don't know how it connects to the generator. Presumably, you have to find a way to connect to the outlet somehow, but I don't know how that's done.


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## LaSwamp

In one of the videos I saw, the guy had the probe clipped to what appeared to be one of the blades of an electrical plug. It was difficult to tell. The clip doesn't fit on the ground part of the plug, so it had to be clipped either to the hot blade or the neutral blade. I guess the ground clip on the probe would clip to the ground rod on the plug? Or would it clip to the other blade? 

It seems there has to be a simple way to get a waveform reading.


----------



## mtucker

One thing to keep in mind when you measure your home AC is that your scope probe likely has its ground lead (the one with the alligator clip) connected to the earth ground that the scope is powered by. They are tied together in the scope. So if you connect the ground clip to the hot of your AC, then you have shorted hot to ground and something is going to give. You normally have to use both leads on a scope to measure a V potential difference, but since your scope is likely connected to earth ground and earth ground is connected to your house neutral in your breaker box, you already have your scope ground clip connected to neutral and can use just the non-ground clip on your scope probe to measure the hot line. If you get the neutral line, you just won't see a signal.
I like to use a ground cheater plug (about $1 at home Depot or Lowes) to plug my scope into to disconnect the earth connection from the scope so I don't have to worry about the probe ground connection.
As far as where to measure, I have an AC breakout box for the power analyzer that gives me an easy connection however with great care you can use a cutoff AC cord (with the insulation stripped some to expose the wires) plugged in to your power source, but then you have exposed live wires. Just be very careful if you go this route.


----------



## tvl

LaSwamp: There really isn't anything too difficult about using a scope and viewing a waveform, However, there are a few things you should be aware of when doing so. If interested and this hasn't been suggested in an earlier post, I would strongly suggest viewing the following video:






*Note*: you can certainly view the waveform output of your generator in the same manner as you would the electrical system in your home. If your generator supplies 240 VAC as well as 120 VAC, I would suggest against connecting your scope to the 240 VAC without the use of a small stepdown transformer, unless you are using the appropriate probes. Not knowing your particular scopes input rating, you should certainly ensure your current probe is set to the 10X setting when viewing the 120 VAC source .......... using a high voltage differential probe kit would certainly be the safest method, but not completely necessary if one is very careful and ensures everything is done correctly. I'll stop with that!


----------



## LaSwamp

I'm just planning on testing the 120VAC outlets, nothing 240VAC. The main reason I got the scope was to try to figure out strange readings I was getting with my multimeter when testing Hz on my Wen GN400i inverter. It should have read a clean 60Hz, but the readings were all over the place. Something seems odd with the signal and I was hoping to nail it down with the scope. 

I have one of those bonded-neutral plugs. Can I clip the scope probe to one of the blades and use that? Or will that be a Bad Thing? I can always clip to a power strip (or something like that) and plug it in, right? I'm just going to snap a pic of the waveform so I can post it. I'm not going to be doing a lot of experiments with it, at least not yet. It really seems like a cool device, though. I'm not an electrical engineer, so I don't understand a lot of how it all works, or the terminology.


----------



## tvl

LaSwamp:

I'm going to stick my neck out and try to help. It's obvious you're inexperienced with a scope, but it's also obvious you're wanting to learn and it seems you're determined to use your newly acquired tool. In the interest of safety and not doing any harm to yourself or the scope, I will make a suggestion that *should* work fine for your *IF* you make certain everything is connected properly *before applying power*:

*Note*: the following method is not the only way to take a measurement, but I feel it might be the simplest for you!

1) Get yourself a regular power strip
2) With the power strip *NOT CONNECTED* *OR PLUGGED IN* to your generator or any other 120 VAC outlet, connect one of your oscilloscope's probes to the hot terminal of one of the power strip's receptacles (_the shorter of the two open slots_). You can use a dummy plug as you mentioned in your post, *ensuring* you connect to the proper blade or whatever other method you feel comfortable using. Also *ENSURE* the probe is set to 10X attenuation!* Do not connect the probe's ground clip to any terminal - better yet, completely remove the grounding clip from the probe!*
3) Once steps 1 & 2 are complete, the scope's probe is now connected and ready to take a reading, but obviously there's more! *At this point and before proceeding to the next step, please do ensure the power strips ON/OFF button is set to OFF!*
4) I believe you mentioned your generator has a floating neutral and you have made or purchased a bonding plug. *Is this correct?* If so, push the bonding plug into one of your generator's 120 VAC outlets. This will bond your neutral to ground.
5) Again after *ENSURING* the power strips ON/OFF button is set to *OFF*, plug the strip into one of the generator's 120 VAC outlets.
6) Now is a good time to also plug your oscilloscope into one of your generator's 120 VAC outlets
7) Start your generator and allow time for it to stabilize
8) Once stabilized, *power on* your oscilloscope. If this step and all previous steps have been followed correctly, the scope is now ON with one of its probe's connected to the hot terminal of a receptacle on the power strip AND the ground clip has been removed OR is NOT connected to anything.
9) At this point, if you're certain all steps have been followed correctly, everything is connected properly and the scope's probe is set for 10X attenuation, you can now power ON the power strip.
10) You should now see the waveform you have been looking for and also get the other measurements you wanted - such as frequency.

*Disclaimer: You're doing this at your own risk. I will not be responsible for any damage to you or your equipment. This certainly isn't rocket science, but anything can go wrong if one is not extremely careful and observant. I'm just trying to help, but was very hesitant to do so!*


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## LaSwamp

Thank you, TVL. That worked perfectly. I finally got some waveforms!

I first tested wall power. As you can imagine, it was a perfect sine wave. Very smooth and consistent. 

I was going to wait until the weekend to test the generators, but the suspense was simply too much. So I pulled out the Wen and fired it up. That's the generator that was giving me wonky Hz readings, so I was very curious to see what the waveform was going to look like. When I pulled it up, the waveform looked... good. It had a very slight distortion around the peaks, but it looked almost identical to the wall power waveform. It was what you'd expect from a gas engine inverter. I was pleasantly surprised. I feel a lot better about it now. I'm not sure why I was getting weird Hz readings. 

I decided to pull out the Coleman Powermate from 2005 that's in my collection. I wasn't expecting a very clean signal and it wasn't. It had the basic shape of a sine wave, but it was very jagged. I would not want to run anything on it for very long. I was going to snap pics of the waveforms, but I'm still trying to figure out how to do it. I was looking to see if I could get it to display Hz and VAC on the screen with the waveform but I could not figure out how to do it. I found Hz on another screen, but I could not find VAC anywhere. There has to be a way to do it, I would think. 

I'm going to post pics of the waveforms when I figure out how to get the pics. I was going to try today, but it was Swamp People hot outside. I need to do it when I have more time to tinker with how all of that works.


----------



## iowagold

super super expensive to buy one...
a broad spectrum analyzer for elf to lets say 1ghz... (they are super pricey to buy at that wide range.and certified)
we rent them for the smaller jobs where we have to look at interference or trash in the air or power.
they rent for 5K per week....
way way out of line on price for this small home hobby stuff... but that is the kinda of instrumentation you need to chase super weird power issues.
we had purchased one back in 2014 for $60k (lease to own on a job) it did not take too long to pay for it out of the rental!
but it was stolen from storage along with lots of other cool items back 4-5 years... wow time flies!

that was the tool we went to for looking at inverter gens!
nice to be able to see the whole band scope feature and see the trash if there was any spikes!

we found 2 bad transformers in the close in area to me and reported them to the utility.
they promptly replaced them and no more hash noise on the hf radios!

depending on the scope they can work for some things like this if you have the proper probes and special band pass filters.
some of the HP scope units had plug in features for this.

yea i have a couple of good books on the scope pages that help with complex scope operation.
pm if you need links.


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## LaSwamp

For what I needed to find out about the signal from the Wen, I didn't need anything radical. I was happy to see that the scope recognized the the signal as a sine wave. The waveform looked pretty good, all things considered. I no longer have reservations about using the Wen to power anything. It looks almost identical to wall power. OMH was right that there was likely nothing to worry about. 

As for the Powermate... yeah, not so much. It looked like a sine wave wearing a fur coat. It's definitely not a generator to use for anything sensitive. I don't know what to expect when I scope the Firman, but I'm not expecting anything very clean. It's a typical worksite generator. I suspect the Champion inverter I have will look like wall power, similar to the Wen. 

The scope has a USB port that can download waveform images onto a thumb drive. As soon as I get that figured out, I will post them all on here. Now I want to test the built-in inverter in my truck. It's probably not clean, but we shall see. So stay tuned, waveforms will be incoming.


----------



## drmerdp

Glad you got it figured out. You can always take a picture of the monitor and upload it. All good either way.


----------



## LaSwamp

drmerdp said:


> Glad you got it figured out. You can always take a picture of the monitor and upload it. All good either way.


There's a way to save the image, but if push comes to shove, I can always just snap a pic of the scope itself. Since I have tomorrow off, I am planning on getting out there early and catching some waveforms.


----------



## LaSwamp

Okay, here some waveforms I promised. 

Here's the basic calibration form:










I had to adjust it a bit, but that looks about as close to perfect as I could get. First up for testing is the Coleman Powermate. It's from about 2004-05, last used extensively during Hurricane Gustav in 2008. 




























I'm not sure how bad that is, but it doesn't look great. As waveforms go, that may not be too bad. 

Next up, the waveform I've been wanting to see since I bought it, the Wen GN400i open frame inverter:




























That seems to look pretty good to me. Maybe a bit of distortion near the top of the wave, but I'm presuming still plenty fine for powering anything. I'm not seeing what was giving my DMM so much grief, but maybe I'm missing something?

Next up, the Firman P03602. I've been curious about this one, although it's not a secret that THD is high for this model. Just how bad is it? 




























I know that's not inverter power, obviously, but how bad is it? It's rated at 25% THD. Does the waveform reflect that? 

I'm going to scope the Champion 200913 this afternoon since it's at another location. It's an open frame inverter. I'm expecting it to show similar to the Wen. 

Let me know your thoughts, opinions, and observations, guys!


----------



## drmerdp

The old powerate is no surprise, they notoriously had sawtooth waveforms.

The WEN generator looks good. No complaints. Would like to see your grid readings for comparison. 

The fireman is way worse then I would have expected. There are basic generators in same price range have cleaner outputs.

I wonder how close to the same image my little pocket scope would produce.


----------



## iowagold

the wen looks ok
wow a lot of rotor slot noise on the others!


----------



## LaSwamp

I wasn't really expecting very clean power from the Coleman or the Firman. Clearly, they are both worksite generators. I'll use them as backups and loaners should one of my neighbors need power in an outage. It's better than no power. I'd imagine using them for a short period of time won't hurt anything, which is typically how outages go when weather events knock it out. People usually just need power for a few days to run a fridge, some fans, or a window shaker. 

So, I had a chance to sit down with the Champion inverter, my newest generator, to see what kind of power it put out. It was a strange afternoon with some odd surprises. I powered it up and let it warm up. I then set up the scope. No matter what I did, the following results happened below.

First, the generator itself:










The waveforms:



















I was not expecting that. I tested the power from the outlet itself, then through an extension cord, and then through a power strip. No matter what I used, that was the waveform I got. 

Baffled, I decided to plug in the bonded-neutral plug I got, the one I use to cure the open-ground fault on the Isobars. As soon as I plugged it in, this is what I got:










I was really surprised by that. I removed the plug and reinstalled it a few times to make sure it was actually the plug that was making the difference. It was indeed the plug. What I don't understand is that my Wen inverter, which also has a floating neutral, made clean sine waves right out of the box, no bonded-neutral plug needed. I was expecting the same from the Champion, but no. It produced what looks like very dirty power out of the box. The bonded-neutral plug is needed to get it to make clean power. What's up with that? Has anyone seen that before from an inverter? 

The other strange thing was that when I turned off the fuel valve to burn off the gas in the carb, I was expecting it to run for about a minute or two and then sputter out. Well, that did not happen. After about 20 minutes, the Champion was still running strong. I had to manually shut it off. I pulled the fuel line and discovered that even with the valve closed, it was still allowing enough gasoline to flow to keep the carb full and the engine running. That's not so good. I'm guessing I can contact Champion and let them know the fuel valve is leaking? It should be an easy part to replace, as long as the fuel tank is empty. 

Just for Schlitz and giggles, I decided to test my truck. It has a built-in inverter that puts out 400w of power. I've never really used it. It's not all that useful except to charge a a phone or laptop. It's not enough power to run anything intensive. First, the truck:










This is the waveform it outputs:










Clearly, it's a modified sine wave. That looks like a typical budget-friendly vehicle inverter. Unless I just have to have power someplace remote, I'm not sure if I will ever use it. 

It was an interesting afternoon. I'm glad I caught the problem with the fuel valve on the Champion. I'm not sure why the signal is so distorted without the bonded-neutral plug installed. 

Thought?


----------



## drmerdp

I’m not sure what to make of the champions improved waveform with a neutral bond. Good thought To experiment with the bonding plug.


----------



## LaSwamp

drmerdp said:


> I’m not sure what to make of the champions improved waveform with a neutral bond. Good thought To experiment with the bonding plug.


I was very surprised to see that, given that Champion is an inverter. I was expecting the power to be very clean. Unless there's a ground loose somewhere, I am baffled over the scope readings.


----------



## tvl

Your scope may offer some hints as to why the waveforms differ:

First, can you share what the *Volts/Division* setting is each of the photos

Your scope also likely has the ability to display Vpp (voltage peak to peak) and RMS voltage. It would be interesting to see what these values are!


----------



## LaSwamp

tvl said:


> Your scope may offer some hints as to why the waveforms differ:
> 
> First, can you share what the *Volts/Division* setting is each of the photos
> 
> Your scope also likely has the ability to display Vpp (voltage peak to peak) and RMS voltage. It would be interesting to see what these values are!


For which generator?


----------



## tvl

I guess the one you're most concerned about ................. the Champion??


----------



## LaSwamp

tvl said:


> I guess the one you're most concerned about ................. the Champion??


I have that generator at another location, so I don't have access to it now. But yeah, that waveform was not was I was expecting from an inverter. The only way I got away from that reading was by plugging in the bonding-neutral plug. That tells me that it has something to do with grounding. Maybe the inverter board is not grounded correctly? Has anyone seen something like that before? I would presume that the inverter should be making a very nice sine wave without having to plug anything in to it, right?

I can make it work using the plug, granted, but I'm genuinely curious about _why_ I might have to.


----------



## LaSwamp

I have a friend who has a Homelite generator, the UT905700. It looks like a pretty nice unit. It's got a Yamaha engine, for what that's worth. My friend picked it up from Home Depot just before Hurricane Isaac in 2012. He used it for about 5 days during the outage after the storm passed. It appears to have been kept outside for at least a couple of years on a back porch. I told him I'd take it back to the workshop and see if I could get it running again. The gas in the carb did not look or smell like gas. It was... nasty. I took the carb apart and soaked the jets and emulsion tube in Seafoam. Drained and cleaned out the gas tank. I replaced the rubber fuel line and filter. The original oil was in it and it looked bad. I changed it with Mobil 1. Using fresh gas, it runs fine now. I told him he's going to keep it in his garage from now on. This is the unit:









I let it run for a while to make sure all was well. While it was running, I captured some waveforms for you guys. I also wanted to make sure it was putting out power. 










It's no inverter signal, but it's better than I had expected. It looks better than my Firman. 










I wouldn't power anything too sensitive with it, but my guess is that it would be fine for fridge and window a/c work. 










The engine is a Yamaha model. I don't know who makes the other components. Seems like a nice generator.


----------



## drmerdp

LaSwamp said:


> I have a friend who has a Homelite generator, the UT905700. It looks like a pretty nice unit. It's got a Yamaha engine, for what that's worth. My friend picked it up from Home Depot just before Hurricane Isaac in 2012. He used it for about 5 days during the outage after the storm passed. It appears to have been kept outside for at least a couple of years on a back porch. I told him I'd take it back to the workshop and see if I could get it running again. The gas in the carb did not look or smell like gas. It was... nasty. I took the carb apart and soaked the jets and emulsion tube in Seafoam. Drained and cleaned out the gas tank. I replaced the rubber fuel line and filter. The original oil was in it and it looked bad. I changed it with Mobil 1. Using fresh gas, it runs fine now. I told him he's going to keep it in his garage from now on. This is the unit:
> 
> View attachment 9897
> 
> I let it run for a while to make sure all was well. While it was running, I captured some waveforms for you guys. I also wanted to make sure it was putting out power.
> 
> View attachment 9898
> 
> 
> It's no inverter signal, but it's better than I had expected. It looks better than my Firman.
> 
> View attachment 9899
> 
> 
> I wouldn't power anything too sensitive with it, but my guess is that it would be fine for fridge and window a/c work.
> 
> View attachment 9900
> 
> 
> The engine is a Yamaha model. I don't know who makes the other components. Seems like a nice generator.


The engine is certainly its best attribute. Every time you post waveform I get closer to upgrading to a real mans scope lol.


----------



## iowagold

lol dr!
yea the fluke power meter might be the ticket!

kinda crazy on the bumps on the different gens...
must be the rotor slot noise...
we had trash like that on the BIG 1200 hp electric motors....
on motor spin down braking it was bad enough to trip out the inverter drive for the motor.

it was a flashed over slot bars on the rotor...
pretty cool!
yea the expensive spectrum unit found that one!
$250k later in motor and drive repairs it was back up and running!


----------



## LaSwamp

drmerdp said:


> The engine is certainly its best attribute. Every time you post waveform I get closer to upgrading to a real mans scope lol.


Ha! It took me a while to bite the bullet and get one. It's turned out to be a lot handier than I thought.


----------



## LaSwamp

Drmerdp, I wanted to mention to you that if you're in the market for a scope, keep an eye on the Rigol clearance site. They don't have much at the moment, but they just did a huge sale not long ago. Some of the scopes were going for 75% off. I almost picked up another one but resisted the urge. They go pretty fast, so you'll need to watch the page. If you catch the sale right, you can pick up something really nice for a huge discount. 

Clearance | RIGOL


----------



## LaSwamp

Picked up another waveform from a generator, this time a Firman T07571. It's a tri-fuel non-inverter generator. A friend of mine picked it up right before Ida. It worked fine except the electric start stopped working on it almost immediately. I told him I'd stop by today and take a look at at. We got Firman tech support on the line to try to diagnose what might be wrong. Tech support ended up concluding the solenoid was bad and is sending my friend a new one and a new switch. I'm hopeful that solves the issue. The unit can still be started with the pull cord, but he wants to be able to use the electric start, naturally. 

I took the opportunity to attach the scope. The results are surprisingly good from what I can tell. 

This is the unit:










These are the waveforms:









A bit of sag but not too bad looking for a non-inverter.
























I'm not sure why the voltage is showing around 60 VAC. That doesn't make much sense. Hz looks correct. I tested voltage with a DMM and it showed around 124 VAC. I've never had my scope be that off before with the voltage reading. I can't seem to get an accurate reading on voltage for some reason. 

Seems like a nice generator. The tri-fuel option is nice, especially considering how difficult it was to get gasoline after the storm.


----------



## drmerdp

Looks typical for the price point. The top of the wave is better then the bottom. It’s a good buy all things considered. 

Thanks for posting more waveforms pics.


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## McCorby

“I'm not sure why the voltage is showing around 60 VAC. That doesn't make much sense. Hz looks correct. I tested voltage with a DMM and it showed around 124 VAC.”

I’m guessing it’s because of where your measurement cursors are positioned…..?


----------



## LaSwamp

McCorby said:


> “I'm not sure why the voltage is showing around 60 VAC. That doesn't make much sense. Hz looks correct. I tested voltage with a DMM and it showed around 124 VAC.”
> 
> I’m guessing it’s because of where your measurement cursors are positioned…..?


To be honest, I'm not sure. As far as I know, I don't have the cursors set. I really just wanted to get a VAC reading from the output. Testing other generators, I've gotten close to 120 VAC from the probe. I haven't changed any settings. When I need an accurate VAC reading, I just use my DMM. I'll have to keep doing that until I can figure out what's causing the weird readings on the scope.


----------



## iowagold

a bit lumpy but that can be slot distortion in the rotor or stator.
did you get a reading with a bit of a load?
and incandescent light would be a good load .... something with out a motor in it.

that brings up a great idea why they do not use square or rectangle wire or potted wire in the gens...

think on this 
if the wires were perfectly tuned in the slots you should have a perfect wave...


----------



## Old man here

LaSwamp said:


> To be honest, I'm not sure. As far as I know, I don't have the cursors set. I really just wanted to get a VAC reading from the output. Testing other generators, I've gotten close to 120 VAC from the probe. I haven't changed any settings. When I need an accurate VAC reading, I just use my DMM. I'll have to keep doing that until I can figure out what's causing the weird readings on the scope.


Post #112 is your clue. Move your your measurement cursors to the top and bottom of the waveforms and watch the voltage readout change.


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## tvl

LaSwamp said:


> To be honest, I'm not sure. As far as I know, I don't have the cursors set. I really just wanted to get a VAC reading from the output. Testing other generators, I've gotten close to 120 VAC from the probe. I haven't changed any settings. When I need an accurate VAC reading, I just use my DMM. I'll have to keep doing that until I can figure out what's causing the weird readings on the scope.


1) Is this waveform taken from a *floating neutral* generator?

2) If so, and based on your probe connections, this may be nothing more than *Ghost Voltage* you are measuring ........................ which is very likely since you are reading around 60 VAC.


----------



## macdenewf

tabora said:


> PowerMate PM0126000 No Load
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> PowerMate PM0126000 Half Load


That ds212 looks like a convenient little piece of equipment. After reading through many of the posts and looking at other posts on how to calculate THD apparently most scopes require a Fourier transform calculation to get to a percentage answer. Most lower analyzer meters will make the calculation. I haven’t done a Fourier transform since college and being honest probably couldn’t even do one now. Does this ds212 perform the calculation or does it require the math to be done manually? 
if it’s calculated for me…a hundred off Amazon is well worth it for me to see how my generator is performing. 
cheers.


----------



## Old man here

macdenewf said:


> That ds212 looks like a convenient little piece of equipment. After reading through many of the posts and looking at other posts on how to calculate THD apparently most scopes require a Fourier transform calculation to get to a percentage answer. Most lower analyzer meters will make the calculation. I haven’t done a Fourier transform since college and being honest probably couldn’t even do one now. Does this ds212 perform the calculation or does it require the math to be done manually?
> if it’s calculated for me…a hundred off Amazon is well worth it for me to see how my generator is performing.
> cheers.


This is what I use for THD readings.
Fluke 345 Power Quality Clamp Meter
I have a regular scope as well, but it does not give THD readings. Equipment for those readings is rather expensive.


----------



## LaSwamp

After replacing the Torch plug and putting in oil and fuel, I was able to capture some waveforms from my new Wen 56225i inverter. First, the inverter:









Once you remove the side panel, everything seems fairly easy to get to. It started up without incident and ran very smoothly. I got my DMM out and the inverter tested at 124.5 VAC, identical to my GN400i. Just like with the 400i, I could not lock onto a Hz reading. It jumped all over the place. It's probably a DMM issue. Next was the scope. 

Power output was not very smooth at first. It was jumpy and a bit jagged:




















I discovered that this Wen has the same issue as the Champion. You have to use the neutral bonding plug. For some reason, that cleans up the signal on the scope. Notice the Hz reading. That will become relevant later. 

I was still getting weird readings, even after using the neutral bonding plug. The display was a bit erratic and jumped around. Plus, the Hz readings kept jumping up and down. That was strange. I hadn't seen that before when testing my other generators, even the non-inverter ones. There was some noise in the signal as well, which was also out of place. 










I caught it on one of the frequent Hz bursts to above 80 Hz. 










I was a bit perplexed. The other inverters I have don't do that. Hz is always stable, as is VAC. I started brainstorming to try to figure out what was going on. Why was I getting such anomalous readings from this inverter? 

I had to run a fairly long power cable from the scope to the wall outlet in the garage. I noticed that the power strip I was using that was connected to wall power looked old. It was yellowed and very worn looking. I wondered if I might be having issues because of that. I removed the old power strip and replaced it with a known-good APC one. After that, the signal seemed to clear up considerably. 










The Hz stopped jumping up and down as well. It remained stable at 60 Hz, as you would expect. 










Apparently, from what I saw, the old power strip I was using to power the scope was causing strange readings from the inverter. I'm not sure how that would happen, but once I removed the old strip from the power chain, the readings cleared up and the inverter readings became what you'd see from any other inverter. VAC is off, but that appears to be because my cursors are not set correctly. I did confirm the inverter is outputting 124.5 VAC, though. 

I pulled the old power strip out of my rotation since it seems to be causing issues. My takeaway is to make sure the scope is getting clean power from the wall or readings might be wonky.


----------



## tvl

LaSwamp said:


> I had to run a fairly long power cable from the scope to the wall outlet in the garage.


If you're willing, you might won't to conduct one other test to see if it makes any difference in your results. Instead of plugging your scope into one of you home's wall outlets, plug the scope into one of the generator's outlets and then conduct the same test. Of course, if the wall outlet is receiving its power from the generator, then forget what I am suggesting ........ as it won't make any difference at all.

If the wall outlet you utilized truly *isn't* receiving its power from the generator, then I'd be curious to see if the home's ground conductor was possibly the source of your anomaly .................. anyway, just a thought!


----------



## iowagold

LaSwamp said:


> After replacing the Torch plug and putting in oil and fuel, I was able to capture some waveforms from my new Wen 56225i inverter. First, the inverter:
> 
> View attachment 10241
> 
> Once you remove the side panel, everything seems fairly easy to get to. It started up without incident and ran very smoothly. I got my DMM out and the inverter tested at 124.5 VAC, identical to my GN400i. Just like with the 400i, I could not lock onto a Hz reading. It jumped all over the place. It's probably a DMM issue. Next was the scope.
> 
> Power output was not very smooth at first. It was jumpy and a bit jagged:
> 
> 
> View attachment 10242
> 
> 
> View attachment 10243
> 
> 
> I discovered that this Wen has the same issue as the Champion. You have to use the neutral bonding plug. For some reason, that cleans up the signal on the scope. Notice the Hz reading. That will become relevant later.
> 
> I was still getting weird readings, even after using the neutral bonding plug. The display was a bit erratic and jumped around. Plus, the Hz readings kept jumping up and down. That was strange. I hadn't seen that before when testing my other generators, even the non-inverter ones. There was some noise in the signal as well, which was also out of place.
> 
> View attachment 10244
> 
> 
> I caught it on one of the frequent Hz bursts to above 80 Hz.
> 
> View attachment 10245
> 
> 
> I was a bit perplexed. The other inverters I have don't do that. Hz is always stable, as is VAC. I started brainstorming to try to figure out what was going on. Why was I getting such anomalous readings from this inverter?
> 
> I had to run a fairly long power cable from the scope to the wall outlet in the garage. I noticed that the power strip I was using that was connected to wall power looked old. It was yellowed and very worn looking. I wondered if I might be having issues because of that. I removed the old power strip and replaced it with a known-good APC one. After that, the signal seemed to clear up considerably.
> 
> View attachment 10247
> 
> 
> The Hz stopped jumping up and down as well. It remained stable at 60 Hz, as you would expect.
> 
> View attachment 10248
> 
> 
> Apparently, from what I saw, the old power strip I was using to power the scope was causing strange readings from the inverter. I'm not sure how that would happen, but once I removed the old strip from the power chain, the readings cleared up and the inverter readings became what you'd see from any other inverter. VAC is off, but that appears to be because my cursors are not set correctly. I did confirm the inverter is outputting 124.5 VAC, though.
> 
> I pulled the old power strip out of my rotation since it seems to be causing issues. My takeaway is to make sure the scope is getting clean power from the wall or readings might be wonky.


good one!
also does the apc strip have any protection like surge or filtering?
yea any coils or wire loops affect the readout.
and can pick up rf trash as well...

so did you use the old strip when checking the other gens as well???
you might have to revisit those posts with updated screen shots..
it still has a couple of little spurs of trash. not much but you could see a bad firing gate or a rotor slot slight out of time.


----------



## LaSwamp

tvl said:


> If you're willing, you might won't to conduct one other test to see if it makes any difference in your results. Instead of plugging your scope into one of you home's wall outlets, plug the scope into one of the generator's outlets and then conduct the same test. Of course, if the wall outlet is receiving its power from the generator, then forget what I am suggesting ........ as it won't make any difference at all.
> 
> If the wall outlet you utilized truly *isn't* receiving its power from the generator, then I'd be curious to see if the home's ground conductor was possibly the source of your anomaly .................. anyway, just a thought!


I did plug the scope into the inverter and took more readings. The outlets on the inverter are recessed so I need to use a power strip to properly seat the probe attached to the hot leg. I've taken readings from house power before and it looked okay. So I don't think the wall power was the problem. I think it was the old power strip. It was the first time using that particular strip to power the scope. Everything stabilized once I removed it.


----------



## LaSwamp

iowagold said:


> good one!
> also does the apc strip have any protection like surge or filtering?
> yea any coils or wire loops affect the readout.
> and can pick up rf trash as well...
> 
> so did you use the old strip when checking the other gens as well???
> you might have to revisit those posts with updated screen shots..
> it still has a couple of little spurs of trash. not much but you could see a bad firing gate or a rotor slot slight out of time.


The APC strip does have surge protection. I don't think it does any filtering, though. It's not one of their expensive ones. Certainly nothing like the Isobars. 

I didn't use the old strip in any of the previous tests. The scope was plugged directly into the wall outlet in the garage when testing the other generators. I used it this time because I was trying to extend the cord out to where the inverter was on the tailgate of the truck. I'm confident that was what was causing the scope to behave a bit erratically. 

It's interesting that the other Wen shows an identical spike in what appears to be the same spot. Is a bad firing gate or a rotor slot-time issue adjustable? As is, the signal looks pretty clean from what I can tell. I'm presuming it's clean enough for any appliances that will run from it. My plan is to use it overnight during an outage to power the window a/c units. It's rated at 9.4 hours but only at 25% output. It drops down to 6 hours at 50% which puts me in the same boat as the GN400i. An extended run beyond that is going to require an auxiliary fuel source. Enter the 9 gallon marine tank... although I really just need to be able to run it from dusk until dawn to keep the insects from dragging me off into the woods during refueling.


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## iowagold

that has the making for the next S king movie!!
mutant LARGE flying bugs carting folks off...
back in the day with creature feature movies that would to have been a real box office hit!

"i'd pay a dollar to see that!"

try just a T for the outlet extension or a home made short cord.
that way no chance on other electronics to mess with the numbers.


----------



## tvl

LaSwamp

I guess what I was trying to convey is:

A) if your scope is attached to your home's electrical outlet, then it is also connected to your home's grounding system ....... that is unless you have removed the ground prong of the plug OR are using a cheater plug - which in either case is not recommended!

B) Using the scope in the manner you had described means the scope is now REFERENCED to your home's electrical ground system. And again, I am assuming you were utilizing only the TIP of the scope's lead on L1 of the generator's 120 VAC outlet AND the scope's ground lead was not being connected or had been removed. If this is truly the case, the scope signal was not referenced properly. You would certainly see a sine wave, but I would suspect the voltage would be incorrect ..................... but by how much, I don't know????

Anyway, just trying to understand what you've done and learn myself.


----------



## LaSwamp

tvl said:


> LaSwamp
> 
> I guess what I was trying to convey is:
> 
> A) if your scope is attached to your home's electrical outlet, then it is also connected to your home's grounding system ....... that is unless you have removed the ground prong of the plug OR are using a cheater plug - which in either case is not recommended!
> 
> B) Using the scope in the manner you had described means the scope is now REFERENCED to your home's electrical ground system. And again, I am assuming you were utilizing only the TIP of the scope's lead on L1 of the generator's 120 VAC outlet AND the scope's ground lead was not being connected or had been removed. If this is truly the case, the scope signal was not referenced properly. You would certainly see a sine wave, but I would suspect the voltage would be incorrect ..................... but by how much, I don't know????
> 
> Anyway, just trying to understand what you've done and learn myself.


Typically, I plug the scope directly into the outlet. This time was different because the inverter was far enough away that I needed to extend the power cord. I used the old power strip as part of the extension. I had never had any issues before when plugging into the wall outlet, so I don't think that was a factor. The only thing I did different this time was using the old strip. Once I removed the strip, the scope behavior became normal. I think the strip was bad and that was what was causing the scope to behave erratically. I didn't have time to do any more tests but the next time I have the scope out I will plug it directly into the wall outlet and test the inverter again. My guess is the readings will be what I would expect. The only thing I wasn't expecting was the signal to be wonky without the neutral-bond plug. I have a Champion inverter that does the same thing. The signal is distorted until I plug in the neutral bond plug. Then it's clean as a whistle. When I talked to Champion tech support, they told me that was expected given I was only testing the hot leg. My bigger Wen inverter doesn't need the neutral bond plug to give a clean signal, so I'm not sure what using only the hot leg has to do with it. All three inverters have floating neutrals.


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## tvl

LaSwamp said:


> Typically, I plug the scope directly into the outlet. This time was different because the inverter was far enough away that I needed to extend the power cord. I used the old power strip as part of the extension. I had never had any issues before when plugging into the wall outlet, so I don't think that was a factor. The only thing I did different this time was using the old strip. Once I removed the strip, the scope behavior became normal. I think the strip was bad and that was what was causing the scope to behave erratically. I didn't have time to do any more tests but the next time I have the scope out I will plug it directly into the wall outlet and test the inverter again. My guess is the readings will be what I would expect. The only thing I wasn't expecting was the signal to be wonky without the neutral-bond plug. I have a Champion inverter that does the same thing. The signal is distorted until I plug in the neutral bond plug. Then it's clean as a whistle. When I talked to Champion tech support, they told me that was expected given I was only testing the hot leg. My bigger Wen inverter doesn't need the neutral bond plug to give a clean signal, so I'm not sure what using only the hot leg has to do with it. All three inverters have floating neutrals.


Fine - I was thinking the different ground reference might be the reason you're getting voltages that you did not expect to see. Anyway, it was just a thought! Then again, it might just be a cursor issue, but unless you have tweaked the setting inside your scope, it is probably still set to <AUTO> .


----------



## LaSwamp

tvl said:


> Fine - I was thinking the different ground reference might be the reason you're getting voltages that you did not expect to see. Anyway, it was just a thought! Then again, it might just be a cursor issue, but unless you have tweaked the setting inside your scope, it is probably still set to <AUTO> .


From what I gather, the VAC issue is due to the cursors not being set correctly. When I adjust the waveform scale, the VAC changes as well. It makes sense that the cursors are reading different parts of the waveform which is what's causing the inaccurate readings. I need to learn how to use the cursors. I wanted to test the waveform on the new inverter before I actually plugged anything important into it. It looks the same as the other Wen unit I have, so it should be good to go. I'll parallel the two Wens together this weekend if I have time to make sure they talk to each other.


----------



## iowagold

LaSwamp said:


> From what I gather, the VAC issue is due to the cursors not being set correctly. When I adjust the waveform scale, the VAC changes as well. It makes sense that the cursors are reading different parts of the waveform which is what's causing the inaccurate readings. I need to learn how to use the cursors. I wanted to test the waveform on the new inverter before I actually plugged anything important into it. It looks the same as the other Wen unit I have, so it should be good to go. I'll parallel the two Wens together this weekend if I have time to make sure they talk to each other.


make sure to connect them together before starting any of the gens.


----------



## Old man here

LaSwamp said:


> From what I gather, the VAC issue is due to the cursors not being set correctly. When I adjust the waveform scale, the VAC changes as well. It makes sense that the cursors are reading different parts of the waveform which is what's causing the inaccurate readings. I need to learn how to use the cursors. I wanted to test the waveform on the new inverter before I actually plugged anything important into it. It looks the same as the other Wen unit I have, so it should be good to go. I'll parallel the two Wens together this weekend if I have time to make sure they talk to each other.


Bingo. The curser is your issue.


----------



## macdenewf

drmerdp said:


> How dirty is your generators electricity? Most people haven’t a clue. Others see their voltage and frequency to be on point and assume their generator is great. The truth is not all generators produce clean power, and the ones that advertise super low THD might not be up to snuff.
> 
> I have scope readings I’ve taken on various generators. Enjoy
> 
> THD = Total Harmonic Distortion
> 
> 
> GRID/UTILITY POWER
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Honda Eu7000is Advertised at less then 3% THD. Loaded or unloaded it’s the same..... perfect. I think it’s actually cleaner then my grid reading.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Honda EB6500x No advertised THD
> 
> 
> No load
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 4600watts load
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Kohler 20Kw standby generator. Advertised at less then 5%THD
> 
> Under approx 1/4 load.


I spent a ton of time researching an easy way to get THD as a percentage but there are seemingly no easy options.
I contacted a couple of different companies...fluke ..and the company that sells the DS 212 but while they both said you can look at a waveform and manually calculate THD...there was no automated function.

I found a piece of software online (daqarta.com) and they have software that calculates THD using a sound card as the data acquisition device. The software wasn't sensitive down in the 60 hz range and when i asked about it for this application - the programmer did a test piece of code of rme to try...and while i think it works...really shows how crappy the mains power in Houston is....i think.

I tool multiple measurements...using a resistor network to drop the input voltage a half a volt.

120v ( no transformer)
pulled power from a 24 v isolation transformer
pulled power from a 16v door bell transformer

so - i either have really crappy mains THD....or a really really good NorthStar Generator.
in all honestly - i want to try this on a pure sine wave UPS or good hands to see if i get something reasonable so i can trust the measurement.

On mains...with all the 3 setups...i'm getting somewhere around 6.1% THD
On my NorthStar 13KW generator i'm getting somewhere around 7 1/2 %
On my Pulsar 12KW generator i'm getting almost 13%
No load on either of the generators at the time

Again - not sure if my baseline of the house is right but plan on doing more testing.
I added some pics...ignore the THD number under the waveform...it only calculates when it is on the spectrum page.

Anyway...if i can get this proved out to be accurate...this is a really inexpensive solution. A 20 dollar sound card and the cost of the program.
Cheers
Mac

Mains Waveform












Mains Spectrum













NorthStar Waveform













NorthStar Spectrum













Pulsar Waveform












Pulsar Spectrum


----------



## 50ShadesOfDirt

I was trying to determine what oscilloscope to get, over in this link:








Oscilloscope - which (inexpensive) model to get?


Requirements (from what I think I know so far): measure genny waveform ... must measure 120v (or "x10" probe?) portable, to some degree (dso nano, or hantek w/ handle) price range: $100 to $300, or thereabouts looks like I need device itself, and some amount of "probes" nice to haves: min 2...




www.powerequipmentforum.com





Very nice find @macdenewf, on Daqarta software! So inexpensive, yet so powerful w/ many use cases (including THD) that I went ahead and purchased a personal license as well. Please keep us posted on the updates to get THD working well, and I wouldn't mind knowing which pieces you used in addition to the Daqarta software (how did you construct the probes)!

I'm off to set up all the pieces (sound card, software, probes, etc.) and try to replicate your good work!


----------



## LaSwamp

Since everyone was good for Christmas, I have new waveforms to post. You guys remember that old Coleman Powermate that my friend asked me to look at? Turns out, it's from around 1986. Much older than I had originally thought when he first told me about it. I wasn't able to get it running in the time I had it in the workshop. He took it home and replaced several parts on it. It's running well now. He wanted me to come over with the scope and see what the power looked like from something that vintage. I was expecting ugly. I will let you, my friends, be the judge. 

First, the generator: 



















The waveforms were jumping all over the place. They look noisy, but not unexpected given the age of the generator. This was probably best tech in those days for portable power. 



















My friend also has two Predator generators from Harbor Freight. Predator has made a name for itself in portable power. There was a poster from a few months ago who was interested in Predator waveforms. I don't know if he is still around. We'll do the big one first. This is the model:










It seems like a heavy-duty unit. My friend ran his entire house with it two times last year, during the winter blast in February (3 days) and after Hurricane Ida in September (2 weeks). The unit ran great. Let's see what kind of power his stuff was getting:



















I guess that would be slot or rotor noise? It doesn't look too bad for what it is. My friend ran all of the electronics in the house, including TVs, without incident. I think he went through quite a bit of fuel, but he had it loaded down pretty good. Several fridges and window a/c units. September down in the swamp is something out of a John Gresham novel. Truth. 

Lastly, my friend had me test his smaller Predator. He was looking for another window unit after the storm and ran across a seller's ad (probably Facebook) from someone also wanting to sell their new Predator generator they got for Ida. Somehow, my friend was able to convince the seller to sell him the a/c unit for $75 and the Predator for $300, if I recall. I think he did well. First, the generator:










Seem to be a nice little rig. It was fairly quiet. Cool thing is that it also provides 240 VAC service. He plans to use it to offload some of the a/c power requirements so he can use the water heater (electric) and clothes dryer with the bigger Predator. All total, he's got around 10 kw if he needs that much power at any one time. Waveforms:



















I was pleasantly surprised. For the price he got it for, it's a clean little generator. The generator is comparable with my Firman, but with a nicer signal. It's only been used once, so it's brand new. I don't think he's going to have any issues using it with anything in his house. 

I'd been meaning to get over there for a while now, and with the day off, this was a good time to finally make it happen.


----------



## drmerdp

Here’s a old test of powermate 5000 circa 1980 something with my cheapo oscilloscope.
The waveform cleans up a bit with half load.


----------



## FlyFisher

LaSwamp said:


> I was expecting ugly. I will let you, my friends, be the judge.


Was that unloaded? Or did you have a load on it? 

Just a thought - check the voltage regulation circuitry and the capacitors in there. You might try replacing them, and maybe use better quality caps. That could help filter some of the "noise", and caps are notorious for degrading over time.


----------



## LaSwamp

No load on it. 

I'll pass it along to him, although I don't know how much cleaner the signal can be made considering the age of all of the components. The signal was probably noisy when it was new. I suggested that he use it for non-electronic tasks. I plan to use my Firman, which also has a noisy signal, for the hot plate and the coffee percolator. He's got 2 other generators, so I doubt he will use it much in an outage. It was interesting seeing if it would work, and how well.


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## iowagold

wow!
lots of slot noise in there!

and lol on the old dog coleman gen!
i remember those.
loud, and not much power...

glad these days we have better gens for sure!
keep the wave forms coming!
love it!


----------



## LaSwamp

iowagold said:


> wow!
> lots of slot noise in there!
> 
> and lol on the old dog coleman gen!
> i remember those.
> loud, and not much power...
> 
> glad these days we have better gens for sure!
> keep the wave forms coming!
> love it!


Growing up, I don't really recall many people using portable generators when the power went off for any length of time. We lost power for about a week back in '92 after Andrew. I don't remember seeing a single generator anywhere. We just did what we could with no power. For one outage a long time ago, I remember my parents using a 1 kw Honda generator. It seemed pretty exotic to me at the time, although it wasn't powerful enough to do all that much with it. So it was interesting to see a generator from the mid-80s. That old Coleman looks like it was probably a worksite generator since it has those odd-looking 240 VAC outlets on it. 

Of course, home generators, and even inverters, are now quite mainstream. Everyone seems to have at least one in their garage. That's the reason there was such a massive rush on gasoline after Ida. Everyone was running generators and no one stocked any fuel before the storm. They burned all of their fuel in a day or two and then rolled out to the gas stations looking for more. Once they drained all of the stations, there was no fuel to be had for several days. Hopefully for next time, people will be better prepared.


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## OrlyP

If you consider the kind of world some of us lived in during the 80s/90s, nobody had any sort of gadget that didn't get its power from a dry cell or Ni-Cd battery. We use them for flashlights or to power a small portable radio... maybe a battery-powered TV. When the batteries ran out, you either stay cuddled up in bed, read the newspaper, or sit in a chair twiddling your thumbs. There were no smartphones, tablets, or Nintendo Switches.... and laptops weren't as common then as they are today.

Now, we have come to rely heavily on electronics, the internet, social media, mobile games, etc. The thought of missing out on a Tweet or unable to join your friend on a campaign in Mobile Legends, puts the fear of God in most of us (ok, my kids). For me, I need to have internet, video streaming, local media streaming (Plex), and A/C. Is that too much to ask? 

But as it is evidently true with a lot of things we take for granted, I think that one reason why generators have become so popular is that.... for better or for worse, the influx of foreign-made generators lowered the generally high outright cost of owning one.


----------



## drmerdp

The only generators I used to see back in the day were for construction. Now every Tom, Dick, and Harry has one.

My backup plan originally was based around having heat and fridges. But rapidly evolved into a life as normal type of system. Then into redundancy and multiple fuel options. Next will be automation.


----------



## iowagold

LaSwamp said:


> Growing up, I don't really recall many people using portable generators when the power went off for any length of time. We lost power for about a week back in '92 after Andrew. I don't remember seeing a single generator anywhere. We just did what we could with no power. For one outage a long time ago, I remember my parents using a 1 kw Honda generator. It seemed pretty exotic to me at the time, although it wasn't powerful enough to do all that much with it. So it was interesting to see a generator from the mid-80s. That old Coleman looks like it was probably a worksite generator since it has those odd-looking 240 VAC outlets on it.
> 
> Of course, home generators, and even inverters, are now quite mainstream. Everyone seems to have at least one in their garage. That's the reason there was such a massive rush on gasoline after Ida. Everyone was running generators and no one stocked any fuel before the storm. They burned all of their fuel in a day or two and then rolled out to the gas stations looking for more. Once they drained all of the stations, there was no fuel to be had for several days. Hopefully for next time, people will be better prepared.


i guess this is why i have gone to tri fuel...
at least i have choices for fuel...
we are more connected now with more work from home internet...
so power is needed.

back in the late 1960's and early 1970's any backup power was exotic.
i had done a system to fire fluorescent light bulbs with 12 volts dc from a car battery.
I made it to the state science fair with that one!
and it still works today!


----------



## Bluwolf

Everybody on my street has a generator. But I'm the only one with dual fuel. My neighbors only buy gas when we're expecting a hurricane. Whenever we have a power outage, my generator is the only one running. After a few times of that happening a few neighbors asked me about why I always had gas. I said I didn't use gas. Showed them the gen shed and the propane tanks. A couple made noises about doing what I did. I even offered to help. But nobody has done it. Oh well, you can lead a horse to water...


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## GenKnot

Bluwolf said:


> Whenever we have a power outage, my generator is the only one running.


Same in my neighborhood. During the February Texas freeze my gen was the only one I could hear running. And I could hear for blocks around me when the wind died down. Most everyone had fled their house or were sitting the cold and dark. I don't get. A small gen is cheap insurance just to have on hand for those not too often situations.


----------



## OrlyP

iowagold said:


> back in the late 1960's and early 1970's any backup power was exotic.


This was true to us until about the early 90's. That's when rolling blackouts in our part of the world started. Almost overnight, every store was fresh out of generators. It took us a few days before we got our hands on one. Thankfully, the power crisis only lasted about a year and since then, we have had reasonably stable power. Still, some remote parts of the country still use generators up to 50% of the time due to unreliable (electric cooperative) or a non-existent local power utility.

Just as recently as a week before Christmas, Cat 5 typhoon Rai tore through Cebu, Surigao, and Siargao island, knocking down everything. It is said that it will probably take a year before power will be restored. Generator sales picked up again during Christmas week as the relatives of the victims did their best to send the generators and other relief items down south. Even then, fuel is also scarce due to the extensive damage on the infrastructure. And so unfortunately, the generators will become virtually useless in a matter of weeks, if not days. My heart goes out to the people there.


----------



## iowagold

that is where solar is a nice thing...
in the warm climates solar rocks if you can keep the panels from getting trashed.
i like the tesla shingle setup...
kinda cool design if you are not in a 300+ mph tornado...
hard to secure unless you have a concrete Q hut bunker..

yea a thick wall concrete dome might be the trick thing with solar on the outside screwed in as small 6 inch panels.
hail and trash resistant would be the key thing to do...
and if they were linked mounted for strength or glued down with VHB 3M tape that would keep them in tact for the ultra high winds..

or do some sort of cover for the panels or a way of rolling them inside when the storms are on the way..


----------



## Bluwolf

GenKnot said:


> Same in my neighborhood. During the February Texas freeze my gen was the only one I could hear running. And I could hear for blocks around me when the wind died down. Most everyone had fled their house or were sitting the cold and dark. I don't get. A small gen is cheap insurance just to have on hand for those not too often situations.


But again, you have to have fuel for the gen to be worth anything. I'm just surprised, after a few times of this, you would think, maybe there's a better way. I'm pretty sure most of my neighbors don't even know what Stabil is. Never mind knowing you could convert to propane (we don't have any access to natural gas). keep a couple 20 lb. tanks around for just such an occasion.

The last hurricane scare we had, there were several people trying to get their gens started because they had left old gas in them and did nothing to put it away properly. And I don't want to look like a know-it-all, saying you could do this or that. If they were to ask I'd be happy to help.


----------



## GenKnot

Bluwolf said:


> But again, you have to have fuel for the gen to be worth anything.


Absolutely! A gen without fuel is just a giant paperweight.

My gen is now converted to NG. My neighbor has 40 gallons of gasoline on hand, and I am helping him convert to NG also. He could not get his genset started during the Texas debacle, but I didn't find that out until afterwards. He needed a can of starter fluid! He is the only other neighbor that I know of to own a genset.


----------



## Bluwolf

GenKnot said:


> Absolutely! A gen without fuel is just a giant paperweight.
> 
> My gen is now converted to NG. My neighbor has 40 gallons of gasoline on hand, and I am helping him convert to NG also. He could not get his genset started during the Texas debacle, but I didn't find that out until afterwards. He needed a can of starter fluid! He is the only other neighbor that I know of to own a genset.


That's very surprising. You'd think after that little disaster everybody would have ran out and bought one. Its a little like closing the barn door after the horses get out, but still... And isn't there the strong possibility that it could happen again this winter? I mean fine, I can see getting caught out the first time. But fool me once shame on you, fool me twice shame on me.


----------



## drmerdp

Bluwolf said:


> Its a little like closing the barn door after the horses get out, but still..





Bluwolf said:


> Oh well, you can lead a horse to water...


lol, Im diggin the proverbs.

Im trying to convince my father to convince my mother to let me re structure their NG piping and run a feed for their generator. Their generator is primarily pro with gasoline as backup. (Trying to avoid gasoline like the plague) Their last outage used up 8 20lb propane tanks last time and thats a lot of lifting and hauling for an old man.


----------



## Bluwolf

drmerdp said:


> lol, Im diggin the proverbs.
> 
> Im trying to convince my father to convince my mother to let me re structure their NG piping and run a feed for their generator. Their generator is primarily pro with gasoline as backup. (Trying to avoid gasoline like the plague) Their last outage used up 8 20lb propane tanks last time and thats a lot of lifting and hauling for an old man.


I'm surprised it would take so much convincing if you're willing to do the work. And never to have to haul any tanks of fuel around again? Sign me up, I've never run gas in mine. If we had access to NG I would do it in a heart beat and keep the propane I have as a back up. That would be the way to go.


----------



## drmerdp

Bluwolf said:


> I'm surprised it would take so much convincing if you're willing to do the work. And never to have to haul any tanks of fuel around again? Sign me up, I've never run gas in mine. If we had access to NG I would do it in a heart beat and keep the propane I have as a back up. That would be the way to go.


Like you said, you can lead a horse to water.… I priced out the project to ~$650 in materials. I think they are just being frugal and short sighted.


----------



## Bluwolf

drmerdp said:


> Like you said, you can lead a horse to water.… I priced out the project to ~$650 in materials. I think they are just being frugal and short sighted.


Ahhh, I see. Penny-wise, pound foolish (I know, another proverb. But you set me up so well  )


----------



## Bulldogger

Bluwolf said:


> That's very surprising. You'd think after that little disaster everybody would have ran out and bought one. Its a little like closing the barn door after the horses get out, but still... And isn't there the strong possibility that it could happen again this winter? I mean fine, I can see getting caught out the first time. But fool me once shame on you, fool me twice shame on me.


 I think they are too dependent on others to come to the rescue. Sometimes, you are the rescue.


----------



## Bulldogger

drmerdp said:


> Like you said, you can lead a horse to water.… I priced out the project to ~$650 in materials. I think they are just being frugal and short sighted.


 Show them some love and offer to pay half or all to keep them comfortable.


----------



## Bluwolf

Bulldogger said:


> I think they are too dependent on others to come to the rescue. Sometimes, you are the rescue.


My point exactly. You live through it once and realize how unprepared you are. If you don't prepare for the next time, especially if you know it's a strong possibility it will happen again, then I have very little sympathy for you.


----------



## drmerdp

Bulldogger said:


> Show them some love and offer to pay half or all to keep them comfortable.


Project is in motion. Assembling parts as we speak. The real root of the issue is they have aspirations of moving but lack motivation and direction. Can’t move if you don’t know where to move too. I don’t see them ever moving to be honest, so the project is underway.


----------



## LaSwamp

The weather warmed up enough to get outside and finish prepping my new Pulsar inverter. The model is the PG2300iS. It seems like a nice little inverter. It's no frills, but I wasn't expecting remote start and Bluetooth for $279. It's rated for 2,300w surge and 1,800w running. It should be plenty powerful enough for quite a few items. This is the model:











With no load, I was reading 124 VAC at a solid 60 Hz. So, right where it's supposed to be. After removing the spark arrestor, replacing the Torch spark plug with an NGK part, and filling it with oil, it was time to pull out the scope and see what kind of power she makes. No surprises. The signal is about as clean as it gets.










I'm pretty impressed with it. For the cost, it was a no-brainer. 



















There's that weird little spike that all of my inverters seem to have. Other generators I test don't have it, so I'm guessing it's just an inverter thing.


----------



## iowagold

what fq is the marker on that little spike?


----------



## iowagold

it could be the clock.


----------



## LaSwamp

iowagold said:


> it could be the clock.


I'm not sure what the fq is for that spike. How would you be able to tell? 

It appears to be around the same place as the spikes for the other inverters. The waveform looks good, so I don't know if the spike is significant. I do find it curious that my inverters seem to all have it, across three brands.


----------



## GenKnot

LaSwamp said:


> I do find it curious that my inverters seem to all have it,


Isn't that just generated by the scope? Since this is a time-domain function being displayed, the initial time is zero.


----------



## LaSwamp

GenKnot said:


> Isn't that just generated by the scope? Since this is a time-domain function being displayed, the initial time is zero.


The non-inverters I've tested don't have that spike. That's why I thought it might be something inherent in the inverts themselves. But I'm not really sure.


----------



## GenKnot

Hmmm 🤔 That's interesting


----------



## LaSwamp

GenKnot said:


> Hmmm 🤔 That's interesting


Both of my Wen inverters have that spike, as does the Champion. I don't think the spike will cause any issues. It's just a bit weird that it's there. I'm not sure why the inverters would have it, unless it's just part of the power profile for that level of inverter.


----------



## GenKnot

@LaSwamp My scope is older than dirt and doesn't have that function. So, I really can't explain the difference between looking at a non-inverter vs inverter gen.


----------



## LaSwamp

GenKnot said:


> @LaSwamp My scope is older than dirt and doesn't have that function. So, I really can't explain the difference between looking at a non-inverter vs inverter gen.


If you look a few pages back, I scoped some non-inverters. You can see the differences. You would think the non-inverters would have spikes. In practical terms, it probably doesn't mean much. I suspect it's mostly academic.


----------



## kirklandlee239

Man! what a great read. learned many things during this read....but now i feel like i did when they stopped airing new episodes of Star Trek..ugh. I shouldnt have had that 2 coffee and binge read the entire thread within 2 hours. As in Tom Bodett, you guys leave the light on, and i'll keep reading, thanks.


----------



## LaSwamp

iowagold said:


> it could be the clock.


I pulled the front panel and was able to determine that the hot port for the parallel connection is the right port. It's the same configuration on the small Wen.


----------



## iowagold

LaSwamp said:


> I pulled the front panel and was able to determine that the hot port for the parallel connection is the right port. It's the same configuration on the small Wen.


i will direct


----------



## drmerdp

LaSwamp said:


> I pulled the front panel and was able to determine that the hot port for the parallel connection is the right port. It's the same configuration on the small Wen.


Same with eu1000, eu2000, eu2200. Neutral on left, Hot in the right.


----------



## LaSwamp

drmerdp said:


> Same with eu1000, eu2000, eu2200. Neutral on left, Hot in the right.


For some reason, it's not marked on the outside, at least not that I saw. Both ports are black. It's not supposed to matter, but I have read reports that if the connection is reversed, it will cause an overload condition.


----------



## iowagold

we use a paint pen to mark the rings on those ports


----------



## LaSwamp

I decided to upgrade to a better scope. After that, it was a fairly long process of trying to narrow down which one I wanted. I knew I was going to go with a more mainstream brand this time around. I looked at several of the Rigol and Siglent models in my price range. There's a fairly new player in the game called GW Instek. They have some interesting models as well. I watched several teardown videos and read lots of reviews. I knew I was going to go with a 4-channel scope this time. I had considered the Instek GDS-1054B but decided not to go that route. I narrowed it down to two scopes, the Rigol DS1054Z and the Siglent SDS1104X-U. I liked the Rigol, but the model I was looking at is a 2014 design. It seems like Rigol is now playing catch up to Siglent in their less expensive models. The Rigol's FFT functions are not nearly as useable as the Instek and Siglent. Although it was a bit more, I decided to go with the SDS1104X-U. Behold:









This unit came on to the market about 6 months ago and retails for $400. That was on the high end of my budget, but I really enjoy tinkering with the scope I have. And the Siglent should come in handy for posting the next generation of generator waveforms here. I'm curious to see what additional information it can give me about the generator and inverter signals.


----------



## speedy2019

I would love to measure my gen with 1 of these but the readings would be pretty bad Im guessing even though its well maintained, as its a non-inverter and is a real cheap gen.https://www.amazon.co.uk/Böhmer-AG-...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=


----------



## LaSwamp

speedy2019 said:


> I would love to measure my gen with 1 of these but the readings would be pretty bad Im guessing even though its well maintained, as its a non-inverter and is a real cheap gen.https://www.amazon.co.uk/Böhmer-AG-Electric-Generator-6500W-Petrol/dp/B078W96337/ref=sr_1_1_sspa?keywords=generator&qid=1648825499&sprefix=genera,aps,78&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyRTM0TE1RWlhKNThKJmVuY3J5cHRlZElkPUExMDQyMjUzM1VVUUxQNEVSREkxNCZlbmNyeXB0ZWRBZElkPUEwODE5Njg0M05RQUpVTzFZQTA0NCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=


Have you seen any THD numbers for it? Not all non-inverters have a noisy signal. Granted, my Firman generator is noisier than WW2. But that may change when I test it with the new scope. Or maybe it will be worse. Sigh. 

In any event, I'll post it here.


----------



## LaSwamp

The new scope came in and I'm tinkering with it now. It's much heavier than the other one. I took a few screen grabs from wall power. Entergy doesn't look really all that great. My inverters make a better looking signal. 


















It saves images natively in .jpg which makes posting them much less clunky. The scope feels much more heavy duty. I like it.


----------



## OrlyP

LaSwamp said:


> The new scope came in and I'm tinkering with it now. It's much heavier than the other one. I took a few screen grabs from wall power. Entergy doesn't look really all that great. My inverters make a better looking signal.
> View attachment 11379
> 
> 
> View attachment 11380
> 
> 
> It saves images natively in .jpg which makes posting them much less clunky. The scope feels much more heavy duty. I like it.




To be fair, it doesn't look like that when it leaves the utility company's generators. Once loads are applied to it... particularly a mix of capacitive, and inductive/reactive loads, you tend to end up with a waveform something like that. 

I imagine that the output of an inverter generator will also be affected similarly.

BTW, how are you connecting the test leads to 120V or 240V AC? 100X probe directly on Hot and Neutral?


----------



## LaSwamp

OrlyP said:


> To be fair, it doesn't look like that when it leaves the utility company's generators. Once loads are applied to it... particularly a mix of capacitive, and inductive/reactive loads, you tend to end up with a waveform something like that.
> 
> I imagine that the output of an inverter generator will also be affected similarly.
> 
> BTW, how are you connecting the test leads to 120V or 240V AC? 100X probe directly on Hot and Neutral?


I hadn't thought of that, but it makes sense. It's not a bad signal, but it's not as clean as I would have imagined. I'm curious to put the scope on the gensets I have here.

I'm only using the one lead from channel 1 to the hot leg. I have 240 VAC here but it's limited to places that are difficult to get to. My 240 VAC generator is on loan to my brother in law at the moment. He used it at Grand Isle after Ida had passed and had knocked out power for a few months. He has since picked up a 13kw Duromax but has not yet returned my Coleman.

One thing that surprised me was that the scope did not come with the more recent firmware, despite the fact that the firmware is almost a year old. I guess it's not a big deal to update it. All it does is five the scope the ability to work with EasyScopeX, which I am going to presume is some manner of PC software. This scope has a network port which my other one does not. That'll be something new to figure out.

ETA: I figured out how to get the software to work with the scope. It's pretty cool. I can control the scope from the PC. That appears to be happening via the USB connection. I'm not sure what the network connector is for. Anyone have experience with that?


----------



## LaSwamp

I pulled out a few of the generators to check with the new scope. Some interesting results, especially with regard to Hz. First up, I put the Titan's inverter to the test. It's 400w max, from the bed outlet. Not really enough power to do much. I guess you could power up some small hand tools. Or connect a boom box for music while tailgating. Not a pretty signal, though.



















Voltage and Hz are spot-on. I'm not sure what the FFT reading is showing, but that square waveform looks a bit harsh. Don't know what the THD might be. 

Next up is the Pulsar inverter. I had a lot of trouble getting the scope to read Hz from it. It was jumping all over the place, from 60 to 128 Hz. I plugged in a neutral bonding plug and the reading stabilized a bit, but it was still hopping around. That seemed odd to me since I would think it would be quite stable. I had a meter on the inverter showing a steady 60 Hz at 124 volts. I have not yet figured out how to get the scope to show VAC. Still working on it. First image is without the bonding plug. Note the Hz, 1.26 kHz. Wut???










Now with the bonding plug.










The plug helps, but the scope is still reading 150 Hz. Yeah, that makes no sense to me at all. FFT below. A lot more detailed than my cheap scope. Hz still wonky. 










The small Wen inverter did the same thing. Weird Hz readings but got a bit more stable with the bonding plug. But still could not get dialed in. Jumped around from 60 to 75 Hz. I'm not sure why. Meter showed 60 Hz stable at 124.5 VAC. 










FFT for the small Wen. Note the Hz reading. 










The odd thing is that the noisiest signal of them all, King Firman, one noise to rule them all, showed a perfectly stable Hz reading. Right on the money. Ugly signal, but at the proper 60 Hz. VAC was 121. 










I used this generator after Ida to power the electric percolator. That was the best coffee I may have ever had. I'm not saying it was the Firman that did it. Possible not having power or coffee for a couple of days beforehand. I plan to use this generator to power the coffee pot and the hot plate. It may be Spaghettis Os, but they will be fine dining. 

The Firman's close up of the waveform. Rotor and slot noise according to Paul. 










FFT reading for the Firman. 










I'm unsure of why the scope had such a hard time with the inverters' Hz readings. Maybe it's a grounding issue of some sort? Both are those gas jug style inverters and may not have the best grounding on them. I didn't test the big Wen inverter, but I'll have to put that one on the scope and see if the scope has trouble locking down a Hz reading. The big Wen's grounding seems to be a lot better than on the smaller inverters.


----------



## iowagold

pretty cool swamp!

message me when you spend the $20k usd for a used spectrum unit!


the bigger the bucks the better the buck rodgers!

if you get in to the units that are $100-200k the detail is even better yet on the fine glitches on the gates...

in the inverters the better the caps the better the signal out...
so if they use computer grade parts or mil spec parts they are less noisy.

and same on parts placement on the boards...
some of the hash is from the front end clock on some units..

all it is .... is a BIG amp...
so garbage in garbage out...


----------



## LaSwamp

iowagold said:


> pretty cool swamp!
> 
> message me when you spend the $20k usd for a used spectrum unit!
> 
> 
> the bigger the bucks the better the buck rodgers!
> 
> if you get in to the units that are $100-200k the detail is even better yet on the fine glitches on the gates...
> 
> in the inverters the better the caps the better the signal out...
> so if they use computer grade parts or mil spec parts they are less noisy.
> 
> and same on parts placement on the boards...
> some of the hash is from the front end clock on some units..
> 
> all it is .... is a BIG amp...
> so garbage in garbage out...


I suspect the Hz jumping around may be a grounding issue. It I were to ground the probe on the grounding screw on the front panel of the inverter, would that cause a problem? It seems I did that with the other scope and it cleared up the jumping Hz readings. That, along with using the neutral grounding plug. If I had thought about it, I'd have pulled out my DMM to see what it was reading. The meter I used showed a steady 60 Hz, so I think the inverters are putting out a fairly clean signal.


----------



## iowagold

you might load up the probe a bit.


----------



## LaSwamp

I was able to get out to my Champion inverter and get some measurements with the new scope. I have a question about how to read VAC with it. What I saw didn't make sense to me, but it may make more sense to you. First, the basic wave. It looks really good, perhaps the best of all of my inverters. 










I had a meter on the inverter while I was taking waveform measurements. It was showing 122 VAC at 60 Hz. The meter on the inverter itself said the same. The scope is also showed 60 Hz. I could not find a reading like that for voltage, though. I had an issue like that with my other scope and Paul and Tabora pointed out that it was a cursor issue. I adjusted the cursors but still seemed to only register about 109 volts. That was the RMS reading, which may not be the correct one. There are several voltage measurements showing on the scope, so I'm not sure which one would be the correct one.










FFT seems to show pretty clean power. 










I had a chance to clean up the carb a bit more this time. After running it, I dropped the bowl and shot carb cleaner in the jets. I reassembled the bowl and shot a bit more carb cleaner in the drain hole. It should be good to go for hurricane season which will be starting in about six weeks.


----------



## iowagold

yup!
harmonic is the key word.

a scope is hard to read the whole picture at the same time...
a spectrum unit works better for the BIG picture.
at least all on the same view...

that is where the BIG bucks are spent.

it is like using a hockey stick to play golf.
sure you can get it to work.... 
but it takes longer to get the results...

it all gets back to "the right tool for the job thing."


----------



## tvl

In the bottom left-hand corner, your scope is displaying a peak to peak voltage of 326 volts. That equals to a peak RMS voltage of 115.24 VAC. This is the effective value of the waveform.


----------



## LaSwamp

tvl said:


> In the bottom left-hand corner, your scope is displaying a peak to peak voltage of 326 volts. That equals to a peak RMS voltage of 115.24 VAC. This is the effective value of the waveform.


That still seems a bit low. RMS should be around 122. Perhaps I'm not using the cursors correctly?


----------



## tvl

Could be your meter is off a bit ................ could be the scope is off a bit What brand and age is the meter? If it's very old, it may need calibrating. Anyway, just saying!!!


----------



## LaSwamp

tvl said:


> Could be your meter is off a bit ................ could be the scope is off a bit What brand and age is the meter? If it's very old, it may need calibrating. Anyway, just saying!!!


It's the Siglent SDS1104X-U. It's a pretty nice scope. It's only a few weeks old. I don't really mind if the VAC is a bit off. I have a meter that's accurate, as well as a couple of DMMs I can use if I need an exact voltage measurement. Still, you'd think a scope would be able to dial in a VAC reading pretty well. I'm still learning how to use it. I have a less expensive scope that I've used up until now. The Siglent is a lot more complex than that one. It's been a lot of fun to tinker with.


----------



## OrlyP

New toy...literally. Can't spare serious money on a proper equipment. I just went for the cheapest and portable scope to see gen waveforms and whatnot.

Just waiting for the 100x probe so I can measure line AC directly without lugging around my variable transformer. We are 240Vrms-only so the Vp-p of 678 V is way beyond the limits of the input (Max. 400 Vp-p)


----------



## GenKnot

Nice!
How about using an AC-to-AC wall wart (maybe 240 to 12 VAC) to look at the high voltage? You would need to come up with a "calibration" for it to read voltage of course.


----------



## OrlyP

GenKnot said:


> Nice!
> How about using an AC-to-AC wall wart (maybe 240 to 12 VAC) to look at the high voltage? You would need to come up with a "calibration" for it to read voltage of course.


Thank you. As a matter of fact, I was considering that. I know I still have a few of those lying around.


----------



## GenKnot

The transformer also provides isolation and therefore a bit safer to use.

If you are concerned about the transformer messing with the waveform, you could always try out a resistive divider such as...


----------



## LaSwamp

OrlyP said:


> New toy...literally. Can't spare serious money on a proper equipment. I just went for the cheapest and portable scope to see gen waveforms and whatnot.
> 
> Just waiting for the 100x probe so I can measure line AC directly without lugging around my variable transformer. We are 240Vrms-only so the Vp-p of 678 V is way beyond the limits of the input (Max. 400 Vp-p)
> 
> View attachment 11725


 Nice! Is that a touch screen?


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## GenKnot

LaSwamp said:


> Is that a touch screen?


Yes it is...
The FNIRSI-1013D Tablet Oscilloscope - A Review #052 - YouTube


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## LaSwamp

GenKnot said:


> Yes it is...
> The FNIRSI-1013D Tablet Oscilloscope - A Review #052 - YouTube


They really are fun to play around with. I have a couple of Duromax generators I want to scope, a 12k and a 13k watt units. They are not inverters, so I'm curious to see how clean the waveform is. I'll post them here when I snag them.


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## OrlyP

It feels right to finally be able to contribute to this thread. Just adding this to the database, FWIW.

Denyo GA-3600









Unloaded:










Loaded 1200W:


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## iowagold

yikes...
i see lots of slot noise...
but is the scope set up right?
i see the 60 hz on the screen...
wonder if those spurs are other harmonic trash?


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## OrlyP

iowagold said:


> yikes...
> i see lots of slot noise...
> but is the scope set up right?
> i see the 60 hz on the screen...
> wonder if those spurs are other harmonic trash?


Yeah... lots of noise there. Scope is setup right. I previously took the waveform from utility power and it shows a near-perfect sine wave.

This weekend, I'll be taking a reading of my other generator.


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## LaSwamp

The generator looks like it's got some age on it and it's not an inverter, so the waveform looks about what I would have expected. The Powermate from the 1980s that I scoped had a similar jagged waveform, as did the Coleman I have that's about 17 years old.


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## OrlyP

As bad as that waveform may seem, I've seen worse. I mean, some are straight up sawtooth-like. Doesn't even resemble a sine wave. 

It is what it is.


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## iowagold

yea hash can get real nasty!
a spectrum unit is nice to see all of the harmonics from the rotor stator interaction...

they can get 400kc trash...
it messes with radio gear.


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## GenKnot

Here are my Champion 46597 3KW gen waveforms. Similar to some of the other non-inverter gens. (Note: I refer to my gen as 3KW even though Champion sells it as 3.5KW...but's that's a lie.)

These waveforms are taken with a 120VAC to 9VAC transformer. Scope is set for 2ms per division. First is wall power...









Generator unloaded...









Generator at about 1/2 load using a 1500W space heater...


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## iowagold

hummm
question and food for thought.'
will the transformer smooth out the spikes some like a choke?


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## GenKnot

iowagold said:


> hummm
> question and food for thought.'
> will the transformer smooth out the spikes some like a choke?


I had thought about that, but I was in a hurry today. It is possible that the transformer might affect the waveform. I might try it again without the transformer...I dunno. All I am trying to do at this point is to prove to myself that I need an inverter generator to run my new high efficiency furnace. This gen is not going to do it.

I had to repair my scope and just got that done this morning. I hadn't used it in years and when I turned it on a few weeks ago there wasn't even a power light. This morning I dug into it and found the primary of the power transformer was open. So, I started removing the wrappings and found a 1A fuse buried under all the tape. I don't know why there was a fuse there since the transformer connects to the incoming power fuse...basically two fuses in series with one buried and unserviceable. I removed the one on the transformer.

Some rewiring and a little soldering along with some J-B Weld and it works fine now.


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## OrlyP

^ A thermal fuse probably. The kind that trips when the winding temp gets too hot to prevent thermal runaways.

I used an auto-transformer set to output ~50V AC for the oscilloscope. All I wanted to see is the waveform. It did occur to me that the transformer can somehow affect the results. But I suppose if it's just a few hundred millivolts, it's practically negligible. Especially, given that we're sampling voltages that are several magnitudes higher.


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## GenKnot

That was what I was thinking that it might be. Unfortunately the writing on it was not readable except for the 1A reference.


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## iowagold

good test equipment has more than one fail safe when in power measurement...
safety first.


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## GenKnot

Yeah, but I'm not worried a bit about it. The scope is from the mid 90s and parts are not available. The transformer showed no signs of being overheated such as discoloration of the windings or the wrapping tape. I think it was just an old age failure. The scope was working just fine the last time I used it, and this time it wouldn't turn on at all. So, it is not a heat failure.

The fuse looked a lot like this one except it had 1A on it. The other markings came off due the varnish that was covering the windings.








10Pcs Thermal Fuse 115C TF Cutoff 250V 2A SM110A1: Amazon.com: Tools & Home Improvement


10Pcs Thermal Fuse 115C TF Cutoff 250V 2A SM110A1: Amazon.com: Tools & Home Improvement



www.amazon.com


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## OrlyP

Maybe that last in-rush current finally broke the camel's back.

I will observe it, nevertheless. Have an IR thermometer ready in case the fuse actually tripped because it did its job. The transformer didn't show any signs of burning owing to the fact that the fuse must have prevented it. Better safe...


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## OrlyP

Here's my main gen. It's a Chinese Honda clone... nothing to write home about, but it has provided us comfort during our last two outages. The brand won't make any sense to anyone living in NA, but I am showing it nonetheless for posterity.

Blackstone BS6800D-SSC - 5kW Peak, 4.5kW Running.









No load:
















15% Load:
















65% Load:
























Ugly as ugly can be. But so far, I have not run into any adverse effects on any load I throw at it.


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## LaSwamp

With up to 15% load, that signal looks much better than my Firman. Which reminds me, I need to test the Firman under load. I'm curious to see how the waveform changes, and into what.


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## iowagold

i always go at 100 watt incandescent light bulb load on each L1 and L2 when testing.


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## londonbookpublishing

Hello, I found this thread quite informative, I always thought that a generator with a motor would give good sine wave. Sadly I'm disapointed... I have a diesel Kubota Loboy gl6500 and don't want I replace it, how can the output be cleaned up?


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## LaSwamp

londonbookpublishing said:


> Hello, I found this thread quite informative, I always thought that a generator with a motor would give good sine wave. Sadly I'm disapointed... I have a diesel Kubota Loboy gl6500 and don't want I replace it, how can the output be cleaned up?


A fuel powered generator can give a clean sine wave depending on what kind of generator it is. An inverter will output a clean signal. High quality non-inverters can also produce a decent signal. Have you scoped your Kubota? A signal can be cleaned up, but it gets pricy quickly. It usually involves using a high-end UPS.


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## londonbookpublishing

No, I don't have a scope. Literally have it away a few months ago thinking I won't need it, and my "buddy" seems to have lost my little portable scope.


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## OrlyP

londonbookpublishing said:


> Hello, I found this thread quite informative, I always thought that a generator with a motor would give good sine wave. Sadly I'm disapointed... I have a diesel Kubota Loboy gl6500 and don't want I replace it, how can the output be cleaned up?


As stated, cleaning up a dirty sine wave isn't going to be economically feasible. Might as well start with an inverter generator.

That said, it's been argued that non-inverter generator power isn't necessarily bad. If not for this thread, you'd be none the wiser and would've kept using the Kubota without worrying..... because it's not going to break anything.


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## iowagold

a good honda inverter gen would be my choice.
they work well for me here.


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## londonbookpublishing

OrlyP said:


> As stated, cleaning up a dirty sine wave isn't going to be economically feasible. Might as well start with an inverter generator.
> 
> That said, it's been argued that non-inverter generator power isn't necessarily bad. If not for this thread, you'd be none the wiser and would've kept using the Kubota without worrying..... because it's not going to break anything.


True, I found this thread because the Coleman 2500 didn't run my son's new Frigidaire smart fridge.

He wanted to get a sine wave inverter to run it off his van, I think a very small under 1000 cheapo generator used to charge a battery might do the trick


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## GenKnot

OrlyP said:


> because it's not going to break anything.


That is no longer the case...it just depends on which modern electronics you have running on the gen. Modern loads such as found in the solar industry or even the newer furnaces have strict limits on the amount of THD they will accept before either being rejected by the load or damaging it.

The effects of high THD has been discussed many times on this forum, but here a few additional links to articles that you may want to go over...








Total Harmonic Distortion’s Effect on Construction Power Equipment


In this post, we will explain total harmonic distortion’s impact on power equipment, and detail what you need to consider when purchasing a commercial portable generator for your construction site.




blog.hy-techroof.com









Modern Generators and Your Sensitive Electronics -


Something that concerns many individuals when they are considering a permanent standby... Read more »




www.midwestgenerators.com




Some of the dangers of running high THD...


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## LaSwamp

I had a chance this past weekend to make it to the coast and test my brother in law's Duromax generator. He purchased it last Fall after Ida. The island got hit pretty hard by the storm. They didn't have power for about 5 months. He used my Coleman generator until his new one was delivered. This is the generator he ordered:









It's a nice generator, but it's a bit of a beast. It should, however, be able to run most of the camp without issues, even the a/c. I did tell him to look at possibly installing a soft start which would be a huge help. I told him to make sure he's got lots of gas on hand to fuel the generator. It has an 8.3 gallon tank, but the generator is going to go through it with the quickness under load and gas is usually very hard to come by in the days after a major storm strike. I will probably suggest he switch it to natural gas and that will resolve that issue. I presume it came with a Torch plug, although he didn't have any deep sockets so I was unable to pull it and confirm. 

I brought my scope down there to take some waveform readings. As usual, there was general weirdness. I can't seem to take a set of waveforms without walking away with questions. This was no exception to that hard and fast rule. Sigh. My Siglent came with 4 passive probes, model number PP510. It _seems_ like a nice probe, although I've read some negative reviews on them suggesting they are "junk." I did have major issues with calibrating the set that came with the scope. Seems Siglent had a bad batch of them that would refuse to calibrate. Siglent sent me two new ones that calibrated without issues. 

I used one of the new Siglent probes. The waveform looked bad, really bad. Granted, the Duromax is not an inverter, but I was expecting a far better waveform than this:










That looks worse than the waveform from my Firman. Even the Predator generators I tested had cleaner waveforms. Hz and VAC were good, but that signal sure looked noisy. I decided to attach my Hantek probe to Channel 2 and take some readings. I wanted to rule out the probe as a source of the distortion. Sure enough, it was a different story:










Not the cleanest signal you will ever see, but much better than the first reading with the Siglent probe. I suspect that this is the more accurate reading. The Hantek didn't come with either of my scopes. I wanted something a bit more high end than what came with the scopes. But even the probes that came with the Hanmatek seem far more accurate than what came with the Siglent. I'm not sure why that would be, given the Siglent is a far higher end scope than the Hanmatek. I'd like to pick up some Tek probes but they are spendy and seem hard to source. 










That's not a bad signal for a standard generator. I don't think my brother in law is going to have any issues using it. As long as he has fuel for it, he should be good to go. He has a 50 amp attachment to the breaker box, so he should be ready for the next major outage. 

I'm not sure why the Siglent probe gave such a bad reading. I'm guessing I'm not going to be able to use the Siglent probes if they are this inaccurate. At least, I'm guessing that it was since I don't believe the waveform from the Duromax was as bad as it was depicted on the scope. I didn't test the other probe to see if it gave weird readings as well. It would seem the rumors about the PP510 are true.


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## iowagold

LaSwamp said:


> I had a chance this past weekend to make it to the coast and test my brother in law's Duromax generator. He purchased it last Fall after Ida. The island got hit pretty hard by the storm. They didn't have power for about 5 months. He used my Coleman generator until his new one was delivered. This is the generator he ordered:
> 
> 
> It's a nice generator, but it's a bit of a beast. It should, however, be able to run most of the camp without issues, even the a/c. I did tell him to look at possibly installing a soft start which would be a huge help. I told him to make sure he's got lots of gas on hand to fuel the generator. It has an 8.3 gallon tank, but the generator is going to go through it with the quickness under load and gas is usually very hard to come by in the days after a major storm strike. I will probably suggest he switch it to natural gas and that will resolve that issue. I presume it came with a Torch plug, although he didn't have any deep sockets so I was unable to pull it and confirm.
> 
> I brought my scope down there to take some waveform readings. As usual, there was general weirdness. I can't seem to take a set of waveforms without walking away with questions. This was no exception to that hard and fast rule. Sigh. My Siglent came with 4 passive probes, model number PP510. It _seems_ like a nice probe, although I've read some negative reviews on them suggesting they are "junk." I did have major issues with calibrating the set that came with the scope. Seems Siglent had a bad batch of them that would refuse to calibrate. Siglent sent me two new ones that calibrated without issues.
> 
> I used one of the new Siglent probes. The waveform looked bad, really bad. Granted, the Duromax is not an inverter, but I was expecting a far better waveform than this:
> 
> View attachment 11995
> 
> 
> That looks worse than the waveform from my Firman. Even the Predator generators I tested had cleaner waveforms. Hz and VAC were good, but that signal sure looked noisy. I decided to attach my Hantek probe to Channel 2 and take some readings. I wanted to rule out the probe as a source of the distortion. Sure enough, it was a different story:
> 
> View attachment 11996
> 
> 
> Not the cleanest signal you will ever see, but much better than the first reading with the Siglent probe. I suspect that this is the more accurate reading. The Hantek didn't come with either of my scopes. I wanted something a bit more high end than what came with the scopes. But even the probes that came with the Hanmatek seem far more accurate than what came with the Siglent. I'm not sure why that would be, given the Siglent is a far higher end scope than the Hanmatek. I'd like to pick up some Tek probes but they are spendy and seem hard to source.
> 
> View attachment 11997
> 
> 
> That's not a bad signal for a standard generator. I don't think my brother in law is going to have any issues using it. As long as he has fuel for it, he should be good to go. He has a 50 amp attachment to the breaker box, so he should be ready for the next major outage.
> 
> I'm not sure why the Siglent probe gave such a bad reading. I'm guessing I'm not going to be able to use the Siglent probes if they are this inaccurate. At least, I'm guessing that it was since I don't believe the waveform from the Duromax was as bad as it was depicted on the scope. I didn't test the other probe to see if it gave weird readings as well. It would seem the rumors about the PP510 are true.


yea the readouts are only as good as the test equipment....
still you can see the slot noise.
so was the bad leads clipping???
almost looks like a clipped top and bottom....
like out of range?
just asking....
makes me think maybe an HP set or another high dollar set might be an idea to try...
garbage in garbage out....
unless it is picking up gen rotor trash in another FQ? other than the 60 hz? (slot trash)
or just a weird harmonic???
yea lots of questions for sure...


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## LaSwamp

iowagold said:


> yea the readouts are only as good as the test equipment....
> still you can see the slot noise.
> so was the bad leads clipping???
> almost looks like a clipped top and bottom....
> like out of range?
> just asking....
> makes me think maybe an HP set or another high dollar set might be an idea to try...
> garbage in garbage out....
> unless it is picking up gen rotor trash in another FQ? other than the 60 hz? (slot trash)
> or just a weird harmonic???
> yea lots of questions for sure...


We ended up having to leave the island a day early, so I was a bit rushed. I wish I had thought to try the other probes in the case to see how they reacted once I had a baseline. I also found it weird that when using the Siglent probe, the signal appeared truncated. It's the probe Siglent ships with the scope so you'd think it would work the best. I only used the one Siglent probe and the Hantek probe to get the results. Maybe I could put the Firman back on the scope and see if it also shows a truncated signal. Then, I could compare and contrast how the different probes handle an identical signal. 

There was some slot noise but that's par for the course on the non-inverter generators. I don't think it's enough to cause a problem, especially since my brother in law won't be trying to use it with a furnace.


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## GenKnot

I took some waveforms while breaking in my new WEN GN625i inverter generator.

This is with light load (6.4 amps) using a Midea 8000 BTU inverter window A/C, and a freezer









This is with a heavier load (31.1 amps) using Midea 8000 BTU inverter window A/C, freezer, space heater, clothes iron.








I can't see a significant difference between these two.  Much, much better than my Champion conventional generator that I posted earlier in this thread.
The WEN has a 40A capability in 120V mode, so the second waveform is at about 77% load.
P.S. I ran the gen in ECO mode for the entire break-in of 5-1/2 hours with the varying loads and it handled everything nicely.


----------



## LaSwamp

I had looked at the GN625i since it has 240 VAC service. It's a great inverter for the price. I needed something with parallel capability, though, that would allow for better scalability. Still, a great choice.


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## GenKnot

LaSwamp said:


> I had looked at the GN625i since it has 240 VAC service. It's a great inverter for the price. I needed something with parallel capability, though, that would allow for better scalability. Still, a great choice.


Yes, if you need 120/240V and parallel capability, then this is not the one to choose.

I only have 120V loads that I wish to run during an outage, so the 40A @ 120V is perfect for my needs.


----------



## LaSwamp

GenKnot said:


> Yes, if you need 120/240V and parallel capability, then this is not the one to choose.
> 
> I only have 120V loads that I wish to run during an outage, so the 40A @ 120V is perfect for my needs.


I bought the biggest inverter Wen makes that still has parallel capability. When in parallel with the Champion, the array is rated between 6-7 kw. That's the setup we used last summer and we had plenty of power. With enough fuel, we could have run for weeks like that if we had needed to. I now also have two of the gas jug style inverters as well, so I have about 10 kw scaled between 4 inverters. I don't know if we're going to see anything this season, but the peace of mind is very nice.


----------



## OrlyP

GenKnot said:


> I took some waveforms while breaking in my new WEN GN625i inverter generator.
> 
> This is with light load (6.4 amps) using a Midea 8000 BTU inverter window A/C, and a freezer
> View attachment 12005
> 
> 
> This is with a heavier load (31.1 amps) using Midea 8000 BTU inverter window A/C, freezer, space heater, clothes iron.
> View attachment 12006
> 
> I can't see a significant difference between these two.  Much, much better than my Champion conventional generator that I posted earlier in this thread.
> The WEN has a 40A capability in 120V mode, so the second waveform is at about 77% load.
> P.S. I ran the gen in ECO mode for the entire break-in of 5-1/2 hours with the varying loads and it handled everything nicely.


That is very impressive. I was pretty sure you should see some distortion when you load up the generator. Is it possible that you have your scope on the other 120V leg that is not connected to the load?


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## GenKnot

No, on this gen the two windings are in parallel for the 120V mode.


----------



## GenKnot

I should have said the two inverters are in parallel.


----------



## OrlyP

That's a nice reading. The gen is taking it like they're all resistive loads.


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## GenKnot

OrlyP said:


> The gen is taking it like they're all resistive loads.


Yeah. I was a bit surprised by how good it looked with just the window A/C and freezer running together. The window A/C has a .72PF and the freezer has a .38PF.

The waveform just doesn't budge!


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## LaSwamp

GenKnot said:


> Yeah. I was a bit surprised by how good it looked with just the window A/C and freezer running together. The window A/C has a .72PF and the freezer has a .38PF.
> 
> The waveform just doesn't budge!


Does an inverter waveform distort under load? I didn't think they did.


----------

