# How steady are your volt readings



## speedy2019 (Jan 29, 2019)

Mine constantly changes, anywhere between 223-245v and its set at 230v. The readings are from my UPS, but my plugin power monitor say a much steadier readings of 223-230v but thats taken every second.


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## iowagold (Jan 22, 2020)

speedy you should also ask what brand of gen set as well!!
so speed what model and brand are you checking?


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## speedy2019 (Jan 29, 2019)

iowagold said:


> speedy you should also ask what brand of gen set as well!!
> so speed what model and brand are you checking?


Im wondering if the volts of all portable generators constantly changes or is it just mine.. This is my gen. https://unionmart.co.uk/product/bohmer-ag-6500w-e-petrol-generator/

Our power company lent us a pretty hefty huge generator a few years ago and hooked it up to the house as they needed to turn off the mains power for a day, and the voltage was rock stable at 240v on that generator.


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## tabora (Sep 6, 2018)

speedy2019 said:


> Im wondering if the volts of all portable generators constantly changes or is it just mine.. This is my gen. https://unionmart.co.uk/product/bohmer-ag-6500w-e-petrol-generator/
> 
> Our power company lent us a pretty hefty huge generator a few years ago and hooked it up to the house as they needed to turn off the mains power for a day, and the voltage was rock stable at 240v on that generator.


The larger the generator's capacity is above demand, the more stable the voltage would be. Maximum allowable voltage from nominal on a small generator is typically +/- 10%, so on your 230VAC Bohmer about 207-253. If you're seeing +/- 10VAC from nominal (about 5%) on your 2600W rated unit, then all is well.


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## iowagold (Jan 22, 2020)

the basic gen sets will vary on the voltage...
depends on the load and start current on the fridge freezer etc.

the best gen set units are the inverter style..
but you will know when you buy one!!
they are pricy!!

a larger gen set in all brands will not see much change with small loads kicking in and out...
but it is a trade off on fuel consumption...

the honda eu7000is is a real good gen set...
but the gallons per hour is higher than the smaller eu2200is...

question for you over in the uk.
do they have natural gas at your location?

here in the usa in town we have natural gas..
and is a good choice for fuel for a gen set...
unless you live in an earthquake area where the natural gas is turned off during a quake event.

we had a tornado tear up a town north of us and they had to turn off the natural gas..
bad deal for those who only had one fuel source...

no power up there for 3 weeks during hot summer days...
flooding etc...

they did better planning now up there...
separated more of the natural gas lines...
and did better for the hospital's back up gen system..

tri fuel or at least bi fuel on the gen set is a good idea!!
then get a large enough gen set to cover your needs...

and the inverter units are best for electronics...
heck think on most new furnace systems now have electronics in them now...
as well as microwave, tv's and more!!

and they only vari by a couple of volts...

I use the little eu2000i honda units... and I can stack 4 of them together with my custom system safe!!
or just use one if I do not need that much power!!

winter time I can get by with one eu2000i unit!!


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## speedy2019 (Jan 29, 2019)

tabora said:


> The larger the generator's capacity is above demand, the more stable the voltage would be. Maximum allowable voltage from nominal on a small generator is typically +/- 10%, so on your 230VAC Bohmer about 207-253. If you're seeing +/- 10VAC from nominal (about 5%) on your 2600W rated unit, then all is well.


I did those test with a 200watt load and nothing was powering on/off, but the readings were constantly changing, The readings were within 225-245 though.



iowagold said:


> question for you over in the uk.
> do they have natural gas at your location?


Im not sure what you mean... I buy bottled butane for my gas fire at home and we have mains gas too... I dont personally have mains gas as I live in the countryside, but busy areas has mains gas, like in the towns. So I have to make do with bottled gas


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## iowagold (Jan 22, 2020)

ahh gasoline is called different things in the uk!! that petrol thing!!
lol!!

yea no load on a standard gen set can be all over the place....
I have seen some standard gens that are 25 volts spread from zero load to 100 watts!! no kidding!! WOW!!

I guess I would load it with 100 watts min at 125 vac or 50 watts at 250 vac all the time with lights I use...
then check the voltage when the larger loads kick in and out...

I have a 25 kw load bank here in the gen repair shop... pricy item!!
but cool when you are hunting for that rare problem or doing a bench mark testing on new gen equipment!

ahh so is the uk like japan where they use butane more and not liguid propane?
japan has an inverter honda unit that runs on butane!! kinda cool item!!

here in the states we have coastal refinery's for gas and gasoline diesel fuel products...
LP is a by product...
and then there is natural gas that is piped to our houses in the city...

then there is also CNG or compressed natural gas that can be in large bottles...
3600 psi or so on that stuff!! and they use it in automotive in some areas... kinda dangerous....

LP is used in fork trucks etc here in the states and is in some cars and trucks as well!!
and lp is used in the country or remote areas... they deliver it in large trucks to 100 lb up to several hundred gallon tanks for like the farms where they use it for drying grain in the fall...

yea I sure would love to see the UK some day!!
some areas are like here in the states wide open spaces...


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## tabora (Sep 6, 2018)

speedy2019 said:


> I did those test with a 200watt load and nothing was powering on/off, but the readings were constantly changing, The readings were within 225-245 though.


200W on a 2600W unit isn't much of a "load". Put 1200W on it and measure it then...


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## speedy2019 (Jan 29, 2019)

iowagold said:


> ahh gasoline is called different things in the uk!! that petrol thing!!
> lol!!
> 
> yea I sure would love to see the UK some day!!
> some areas are like here in the states wide open spaces...


I dont know if out petrol is natural that we get from the station,, all I know its unleaded petrol:tango_face_grin:

The UK isnt that great as the weather is rubbish most of the time, but we dont get real cold snowy winters like you do in the states.



tabora said:


> 200W on a 2600W unit isn't much of a "load". Put 1200W on it and measure it then...


Ah so the voltage being not constant or steady is down to the gen not having much load on it? My gen hasnt had a proper load on it yet or been used for a lengthy amount of time in one go, as a computer, 2 tv's and a few lights doesn't really crank the watts up much....... The voltage meter needle on the gen doesn't jump around at all, but you cannot get the correct readings with those useless analog volt meters they put on generators anyway.


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## Melson (Dec 8, 2019)

Small, non-inverter gensets use a governor to try to hold 50 or 60 cycles. They do a reasonable job but there is a certain amount of engine speed droop as load is applied before the governor can react. Also, many, if not most, small engine gensets are not precision units, their fuel and governor systems may hunt up and down a cycle or so with a light load. They tend to become more stable as load is applied, but may or may not be able to hold rated speed under full load conditions.

Enter the inverter system. These devices use electronic switching to output precise, stable voltage and frequency within a wide range of voltage and frequency input. Which pretty much divorces engine speed fluctuations from the desired output. 

In the Twentieth Century most electrical and electronic devices, by build and design, had robust tolerance for out-of-range voltage and frequency. That ruggedness has been subverted with the advent of digital electronics, the tolerance has significantly narrowed. 
As a power glutton consumer I, for one, probably don't appreciate the effort that goes into supplying our demand for clean, stable and harmonic-suppressed energy. Until, that is, I don't have it :-]


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## speedy2019 (Jan 29, 2019)

Ive had my gen going today for its monthly run, and I have found out, that the voltage gets steadier the more load I put on the gen.. I had just over 400watts on the generator, and that steadied the voltage right down to 227-228v, but as soon as I took it back to about a load of 230watts the voltage jumps all over the place, anywhere from 218v- 230v.(so my uninterruptible power supply says)


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## iowagold (Jan 22, 2020)

always best to have a min load on any gen of that 400 to 500 watts...
easy to do on most applications.
battery charger, lights, fan, router for wifi, modem, etc.
it all adds up.
always run a gen system with a watt meter!!


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## speedy2019 (Jan 29, 2019)

This was the info from the UPS, The input says 230 on the screenie, but it was mainly hovering at 227-228. See how the UPS boosted the output volts to the correct UK voltage of 239v(should be 240). I think the low/high voltages means that the UPS goes over to battery mode if the volts exceed the input voltage values, but I could be wrong.


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## iowagold (Jan 22, 2020)

some use buck boost system..
and if you are on line power is does not use the battery for these features.
what brand and model of ups??
I use apc.
they work well with my honda gens.


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## speedy2019 (Jan 29, 2019)

Its a "powerwalker 2000va/1800watt online ups" and its generator friendly, but I think all online ups will run from a generator. It's the line-interactive ups that are dodgy with generators, unless you get a generator friendly one.

https://powerwalker.com/?page=product&item=10122042&lang=en


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## tabora (Sep 6, 2018)

speedy2019 said:


> This was the info from the UPS, The input says 230 on the screenie, but it was mainly hovering at 227-228. See how the UPS boosted the output volts to the correct UK voltage of 239v(should be 240). I think the low/high voltages means that the UPS goes over to battery mode if the volts exceed the input voltage values, but I could be wrong.


 Sounds like your UPS is out of date; its output can be adjusted (see below). The UK mains supply is about *230 volts AC*. Your generator is producing the currently correct 230V.

The voltage used throughout Europe (including the UK) has been harmonized since January 2003 at a nominal 230v 50 Hz (formerly 240V in UK, 220V in the rest of Europe) but this does not mean there has been a real change in the supply.

Instead, the new “harmonized voltage limits” in most of Europe (the former 220V nominal countries) are now:
*230V -10% +6% (i.e. 207.0 V-243.8 V)*

In the UK (former 240V nominal) they are:
*230V -6% +10% (i.e. 216.2 V – 253.0 V)*

This effectively means there is no real change of supply voltage, only a change in the “label”, with no incentive for electricity supply companies to actually change the supply voltage. To cope with both sets of limits all modern equipment will therefore be able to accept 230V +/-10% i.e. 207-253V.

Looks like your UPS supports Nominal Output Voltage options of 220/230/240 VAC: 

Setting by LCD Module... In bypass or no standby mode, press “Enter” button to enter setting mode. The middle section displays setting entry. The right section display current value of the setting. Press enter to edit the value; the right section will start to blink. Press “select” to change the value. Press “enter” again to confirm and save the setting. If nothing was pressed for more than 10s, the setting mode will exit automatically. Each button pressing must last longer than 1 second. Setting OPV Output Voltage Setting (220/230/240V).


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## speedy2019 (Jan 29, 2019)

I know the UK is suppose to run at 230, but the mains power is never 230v, its between 240-250v thats with a plugin power monitor and the ups readouts. So I have set my ups at 240v.


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## tabora (Sep 6, 2018)

speedy2019 said:


> I know the UK is suppose to run at 230, but the mains power is never 230v, its between 240-250v thats with a plugin power monitor and the ups readouts. So I have set my ups at 240v.


Again, I would suggest that you adopt the 230V standard, especially since your generator is running at 230V. Better to step down than up.


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## Melson (Dec 8, 2019)

tabora said:


> Again, I would suggest that you adopt the 230V standard, especially since your generator is running at 230V. Better to step down than up.


tabora is right-on; appliances and equipment can withstand undervoltage far better than overvoltage. I once scoped and recorded (thank you Drantiz) a ONE cycle decaying spike coming off a small, 60kw Cummins set (Rye Beach, NH) that took out a high-end commercial crowbar OVP add-on; basically a sophisticated surge suppressor. It went-off as loud as a shotgun. Was very effective at clearing all unnecessary management from the room :-]


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## iowagold (Jan 22, 2020)

Melson said:


> tabora is right-on; appliances and equipment can withstand under voltage far better than overvoltage. I once scoped and recorded (thank you Drantiz) a ONE cycle decaying spike coming off a small, 60kw Cummins set (Rye Beach, NH) that took out a high-end commercial crowbar OVP add-on; basically a sophisticated surge suppressor. It went-off as loud as a shotgun. Was very effective at clearing all unnecessary management from the room :-]


and I bet the laundry bill for the company went up that week as well!!
:tango_face_devil:
yea it can be a big deal...
I guess that is why I like the inverter gens...
at least for me they stay super close to what I need.
I did find there are some buck boost transformers now days that are way lower cost from the 1960's prices.
and they now make some for 3 phase to 2 phase and single phase as well.
I just ran in to the company on tues.
I will try to get a few of the models in for testing this next month.


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## speedy2019 (Jan 29, 2019)

At the moment the incoming mains voltage is at 245v and it very rarely drops below 240v


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## drmerdp (Apr 10, 2018)

My AVR generator usually sits at 125-127 at no load and linearly drops to 118 at full load. Any good quality generator should provide voltage output of +/- 5% of its rating. Cheap generators Have outputs that vary greatly. 

Engine speed has a big effect on the voltage too. Over or under spec engine speeds will cause voltages to get wonky. 

So your 240v 50hz generator should be operating at no more them 52hz no load and no less then 48hz at rated load. Adjust your light load engine speed to get to that 52hz mark. If your generator drops below 48hz under your typical load, then it’s inadequate for your use. 

Keep in mind an inverter generator will give you perfect frequency and voltage... something to consider.


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## tabora (Sep 6, 2018)

drmerdp said:


> So your 240v 50hz generator...


 @speedy2019 has a _Böhmer_-AG 6500W-e which is a 2600/2800W 230V 50Hz generator (hence the suggestion to adjust his UPS output voltage to parity).
He has had voltage issues from his UPS since the beginning... https://www.powerequipmentforum.com...1604-voltage-fluxterations-new-generator.html


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## tabora (Sep 6, 2018)

speedy2019 said:


> At the moment the incoming mains voltage is at 245v and it very rarely drops below 240v


Who's your electricity supplier? One of the Big Six, or a smaller player? Are you using a true RMS meter? A *true RMS meter* works by taking the square of the instantaneous value of the input voltage or current, averaging this value over time, and then displaying the square root of this average. The important thing to remember is that a “*true RMS*” *meter* will give you better readings.


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