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generator over voltage
Posted: Sun Jul 31, 2022 1:46 pm
by Justme
Currently struggling through a head fog of illness with a 11kw genny that is giving me an over voltage of 333v ac.
Its a single phase unit.
Tried new AVR's all still give same voltage.
Removing avr & output drops to 30v ac.
Tested all joints & windings for shorts & cant find any but dont have a megga to do a high voltage leak test.
My super cheap scope goes crazy & I cant get any sensible readings, but it does read from the inverter fine.
All googling points to over rpm (its not) faulty avr (unlikely 3 are faulty) or loose connections or high resistance which I cant find any.
I just cant find whats up with it.
Re: generator over voltage
Posted: Sun Jul 31, 2022 7:45 pm
by Westie
Justme wrote: ↑Sun Jul 31, 2022 1:46 pm
Currently struggling through a head fog of illness with a 11kw genny that is giving me an over voltage of 333v ac.
Its a single phase unit.
Tried new AVR's all still give same voltage.
Removing avr & output drops to 30v ac.
Tested all joints & windings for shorts & cant find any but dont have a megga to do a high voltage leak test.
My super cheap scope goes crazy & I cant get any sensible readings, but it does read from the inverter fine.
All googling points to over rpm (its not) faulty avr (unlikely 3 are faulty) or loose connections or high resistance which I cant find any.
I just cant find whats up with it.
Need a bit more info mate, is it brushed or brushless, if brushed how many sliprings 2 or 3?
Re: generator over voltage
Posted: Sun Jul 31, 2022 8:12 pm
by Tinbum
Justme wrote: ↑Sun Jul 31, 2022 1:46 pm
All googling points to over rpm
That would just effect frequency.
Re: generator over voltage
Posted: Sun Jul 31, 2022 9:30 pm
by rogeriko
Put a load on it, like an electric heater 2-3kw and then measure it.
Re: generator over voltage
Posted: Sun Jul 31, 2022 10:01 pm
by newtoallthis
I am a mere Mechanical Engineer, but from my distant memory I have to ask A=are you measuring RMS voltage or Peak voltage.
RMS x √2 = Peak.
So, if you are measuring 230 V and your meter is set to Peak then it will indicate 325V. 240V would indicate 339V.
Re: generator over voltage
Posted: Mon Aug 01, 2022 4:05 am
by billi
rogeriko wrote: ↑Sun Jul 31, 2022 9:30 pm
Put a load on it, like an electric heater 2-3kw and then measure it.
my first thought , too
Re: generator over voltage
Posted: Mon Aug 01, 2022 8:26 am
by Hermit
Hi Justme, sounds like a dud meter or something to me as you say "it reads OK at the inverter". I am thinking that if the inverter accepts the voltage then it must be OK
Re: generator over voltage
Posted: Mon Aug 01, 2022 9:23 pm
by Justme
Hermit wrote: ↑Mon Aug 01, 2022 8:26 am
Hi Justme, sounds like a dud meter or something to me as you say "it reads OK at the inverter". I am thinking that if the inverter accepts the voltage then it must be OK
When did I say that?
The scope reads inverter fine.
Meter reads inverter fine.
Re: generator over voltage
Posted: Tue Aug 02, 2022 12:13 pm
by Westie
newtoallthis wrote: ↑Sun Jul 31, 2022 10:01 pm
I am a mere Mechanical Engineer, but from my distant memory I have to ask A=are you measuring RMS voltage or Peak voltage.
RMS x √2 = Peak.
So, if you are measuring 230 V and your meter is set to Peak then it will indicate 325V. 240V would indicate 339V.
Good point, many cheap multimeters have a peak hold function now... Make sure its not peak holding!
Re: generator over voltage
Posted: Tue Aug 02, 2022 12:17 pm
by Justme
Westie wrote: ↑Sun Jul 31, 2022 7:45 pm
Need a bit more info mate, is it brushed or brushless, if brushed how many sliprings 2 or 3?
Brushless.