# Generator Help Please



## jim0411 (Jul 5, 2019)

I purchased a Harbor Freight 3500 inverter generator. I was using it to power audio and video equipment. I was running everything through a power conditioner. The volt meter on the power conditioner kept fluctuating up and down. My projector shut down several times because of uneven power supply. I ran projector direct into honda 2200 and worked fine. On the Harbor Freight generator when i use a two prong adapter the power smooths out and is steady. I am baffled any help is appreciated.


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## RedOctobyr (Aug 8, 2018)

Welcome to the forum! If it's a recent purchase, I'd probably just exchange the generator. No need to take on a mystery research project if you can just swap it. 

If it helped to just use 2 contacts, instead of 3 with a ground, maybe you're getting some sort of voltage on the ground contact, somehow? Have you checked it with a multimeter? What do you get from hot contact to neutral? And ground contact to neutral? And I guess also hot to ground. I'd check for DC voltage in addition to AC, just to be safe.


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## jim0411 (Jul 5, 2019)

sorry i probably didn't explain very well. The generator has a steady voltage when i plug in power conditioner power fluctuates. When i plug in same power conditioner with an adapter power is steady.


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## RedOctobyr (Aug 8, 2018)

Am I understanding correctly? 

- HF 3500: output voltage is steady. 
- HF 3500 -> power conditioner: output voltage fluctuates. 
- HF 3500 -> 2-prong adapter -> power conditioner: output voltage is steady. 

I would still do the voltage checks that I mentioned previously. It sounds like some sort of interaction between the generator's ground, and the power conditioner, is somehow making things unstable?


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## exmar (Jun 29, 2015)

Definitely a grounding issue. Curious, You have an inverter unit which provides very clean power (OK, probably more of a square than sine wave) and you feed your gear through another conditioner? Does the equipment specifically call for that or are you being conservative based on the bad rap gensets get for "dirty power?" If the gear is designed for the commercial market-plugged into convenient outlet-it can tolerate a pretty dirty electrical environment. Commercial power is anything but clean, has all kinds of droops, surges, spikes and other hash coming in. I've run flatscreen tv's computers, etc. for years on regular gensets with no issues.


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## jim0411 (Jul 5, 2019)

should these units be self grounded? Could it just be as simple as a bad unit? My honda generator doesn't have the same problem and i believe are self grounding. I know absolutely nothing about generators and really need it just to work without these issues and without damaging my electrical equipment.


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## RedOctobyr (Aug 8, 2018)

Could it be just a bad generator? Absolutely, it seems to me. Like I said, if you're within the return period, I'd exchange it. It seems like weird behavior to me, sounds like something is wrong. Now, if there's no chance to exchange it, then by all means, I'd try to dig in more, to try and figure out what's going on. But it should be working fine out of the box, and doesn't seem like that's what it's doing.


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## KRE (Nov 29, 2011)

Your issue is combined harmonics on the ground leg hosing up what the inverter regulators target voltage is.


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## jim0411 (Jul 5, 2019)

thank you everyone. I will return it and see if the next one has the same symptoms. Hopefully just a bad unit. I really am in a position where it just has to work flawlessly. If the next one does it as well i may have no other option to spend the cash on a honda.


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## RedOctobyr (Aug 8, 2018)

If the next one does the same thing, could you omit the power conditioner? 

Searching the reviews here: 
https://www.harborfreight.com/3500-Watt-Super-Quiet-Inverter-Generator-63584.html

Someone said they connected theirs to an oscilloscope, and it was a clean sine wave output, like utility power. If that's the case, the power conditioner may not be doing a lot for you? 

It depends on what the conditioner is trying to do, I guess. If it's trying to smooth out the sine wave, then that shouldn't really be needed. If it attempts to help "fill-in" brief voltage sags, it might be able to provide some benefit. But brief voltage sags due to sudden big loads (such as a compressor starting, which sounds like it wouldn't apply here), can be indicated by listening for the engine suddenly slowing down as a big load hits. And that can be minimized by leaving the engine running full-speed, rather than setting it to reduce the engine speed as the load reduces. 

But I'm not an EE, and I have always been a bit puzzled by power conditioners, and what exactly they're supposed to help with. Maybe they're really effective, I don't know. I better understand how an expensive "online" UPS is able to clean up power, as it can use the input power, and its internal batteries, to sort of re-create the sine wave that is needed.


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## riley804 (Jul 7, 2019)

" I was using it to power audio and video equipment. I was running everything through a power conditioner "

just curious why are you using a generator to power audio and video equipment ? why not use AC ? 

being in the audio hobby myself, I would not use my generator to run my stereo equipment even though it could....but its meant for more important things.


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## speedy2019 (Jan 29, 2019)

I use a UPS with my generator for my pc stuff to bump up the voltage to 240 from generators voltage of 223 and the UPS keeps things steady, or I hope so anyway.


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## riley804 (Jul 7, 2019)

doesnt that get pricey ( fuel ) after a while ? 

what about the constant noise ?


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## RedOctobyr (Aug 8, 2018)

Pretty sure he meant that only while running off the generator (utility power is out, or doing testing), he uses the UPS.


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## jim0411 (Jul 5, 2019)

I run an outdoor movie company. Around 95% of the time we use regular utility power and never have any issues. We do however sometimes need to use generators to power our equipment if we don't have access to power or are 100 yards to the nearest outlet. These events can have 2000-3000 people in attendance and our equipment has to work. I am hoping that it is just a bad generator and all i need to do is replace it.


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## RedOctobyr (Aug 8, 2018)

Please let us know how the swap goes. 

If this is a mission-critical type of application, it may be a case where relying on a single HF product isn't ideal. A Honda would likely be more robust. Or, for that price, maybe you could have a 2nd HF 3500 waiting, if it were needed. Stuff can always happen, to anything, "even" a Honda/Yamaha. 

Or maybe the backup could be a good (sine wave) inverter that could be attached to the battery terminals of a running vehicle, if it could be close enough. 

My generator power for the house is a pair of EU2000i's, in parallel. I originally bought the first one for a different purpose, then it evolved into replacing my big, loud generator for home. A single 3500W generator would be simpler than my parallel set. But one benefit is that I have redundancy, if I suddenly need them, and 1 has a problem. I drain their carb bowls between uses, even with stabilized gas, to try and avoid problems.


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## jim0411 (Jul 5, 2019)

Well did the swap of the generator and new one has same issue. So i guess back to the store and bite it and buy a honda.


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## speedy2019 (Jan 29, 2019)

speedy2019 said:


> I use a UPS with my generator for my pc stuff to bump up the voltage to 240 from generators voltage of 223 and the UPS keeps things steady, or I hope so anyway.


Hi, I was just wondering how does my ups bump up the voltage? I guess if it used battery power todo this then the batts would be flat in no time... Ahhh when a online ups is connect to a generator, the generator only charges the batteries, as the voltage is too far out of range to use the generators power. But I havent still answered my question,,, surely the batts would run down quicker then it can recharge it's self from the generator? And yes its deffo using the generators power when I change over the power source from mains to generator


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## RedOctobyr (Aug 8, 2018)

My assumption has been that it makes up for low voltage by increasing the current draw from the supply power (the generator, in this case).

Pick easy numbers. Say something draws 1000W, at 100V. P=V*I, so I=V/P. Therefore it would draw 10A. 

Now it's being supplied 90V instead. To get 1000W, you'd need to draw 11.1A. So the UPS could increase the current draw from the wall to 11.1A, now the UPS is getting 1000W. It now has enough power to create a 100V output to the load, supplying 10A, and 1000W. 

I'm simplifying, ignoring efficiency losses, etc. And I'm making assumptions as to how they work, though they seem like reasonable assumptions to me. Hopefully someone will correct me where I go wrong.


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## RedOctobyr (Aug 8, 2018)

jim0411 said:


> Well did the swap of the generator and new one has same issue. So i guess back to the store and bite it and buy a honda.


That's a bummer, sorry. I hope the Honda works better for you!


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## jim0411 (Jul 5, 2019)

I think its a bummer too. Now I would just like to figure out the why is it doing this when honda doesn't. I must be missing something. How can power even out by taking a group away? I'm dumbfounded.


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## KRE (Nov 29, 2011)

Again, it's harmonics. The Stator winding pitch on a Honda is totally different than a HF unit. The excitation systems are totally different an that places all odd harmonics in a different place. With the HF unit they lined up with your conditioner an because the HF genset has a closed loop excitation system (Honda as well) anything trash the load gets fed back to the genset. EPG (Electrical Power generation) is a field many think they understand, until they don't. Don't feel bad I've seen guys with 30+ years field experience get stumped by simple stuff like this. Know of two cell carriers that burnt sights to the ground do to combined harmonics. The genset voltage was 240Vac until the load hit it then it went to 340Vac an set stuff on fire. Remember on small stuff(most 700KW an down w/o paralleling ability) your voltage regulator is only looking at the bottom sag numbers, it could care less what the top number is.


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## jim0411 (Jul 5, 2019)

thank you my friend but with all do respect I have absolutely no idea what any of that means. I admittedly am a complete novice when it comes to generators.


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## RedOctobyr (Aug 8, 2018)

Very interesting, thanks KRE! 

Can you help me understand a few things? You clearly know way more about this than I do. 

- Why would running the power conditioner without the ground change the result, and suddenly make it work OK? 
- What is bottom sag, vs the top number? Do you mean it's just trying to maintain a minimum "max" voltage, if you will? Like it wants to maintain your voltage at a minimum of 110V? But it doesn't notice/care if the voltage climbs too high? That would seem odd, so I'm probably misinterpreting. 

Do the harmonics come into play more with the power conditioner (vs traditional loads) because the conditioner is making rapid changes that influence the load on the generator? And the generator's electronics are also making rapid changes to control the output? So you kind of have "too many cooks in the kitchen", and each device is messing with the other, getting into an over-controlling problem?


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## KRE (Nov 29, 2011)

RedOctobyr said:


> Very interesting, thanks KRE!
> 
> 
> 
> ...


Power conditioners have filters, Cap's an some have Scr's in them, this is mostly a minor issue except when small gen sets are being used. Saving on the front side means your going to pay for it on the back side.
Harmonics can be generated from many load devices, an rope start gen sets are very touchy about these. Some units handle it better than others do to design. 

Single phase gen sets are all rated at unity (1.0) power factor (PF) any load that is less (lagging PF) than unity drops the gen sets rating, an after 0.9 it starts dropping like a rock. 

What causes a lagging power factor? Motors, Transformers, SCR''s (these(scr's) are the worst offenders) an a few other devices. 

Voltage reg's could care less about the top number(voltage) they just look at the bottom sag's an even then most do not look at it RMS either. 

You can raise a very low PF but adding in caps, or a heating load if the gen set has extra ability left.
Box stores don't have a clue about generators, an the industry as a whole does not educate the buyer at all, why? Because they give you just enough info to sell, then when it fails do to miss application, the public assumes they are the ones who burnt it up. Which they did but from lack of education about ratings.


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## Danny Porter (Sep 2, 2019)

jim0411 said:


> I purchased a Harbor Freight 3500 inverter generator. I was using it to power audio and video equipment. I was running everything through a power conditioner. The volt meter on the power conditioner kept fluctuating up and down. My projector shut down several times because of uneven power supply. I ran projector direct into honda 2200 and worked fine. On the Harbor Freight generator when i use a two prong adapter the power smooths out and is steady. I am baffled any help is appreciated.


Check to see if the polarity of the generator is reversed, I have a 3500 a couple of months old and today I found out the neutral is wired to the hot side of my 120 volt plug, I was wiring up a boat shed that has no power yet, I was using a induction tester to test the circuits and when I tested the white wire or neutral was hot not the black wire!!!! BLEW MY MIND UNTIL I CHECKED THE GENERATOR RECEPTACLE!!! May explain your grounding issue!!!!


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