Generator over voltage

[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.

 

[Anguz]

how many wires on the avr? got a picture?
sounds like its maybe saturating . and not controlling

 

[Justme]

avr has 4 wires SX460 + - 7 8
+ & - do the actrual controlling via the excitation coil.
7 & 8 must be the power to the avr & its sensing wires.
Why would all 3 avr's do exactly the same?

Must be an issue up stream as it were.

 

[Anguz]

have you twiddled the voltage adjusting screw?

 

[Anguz]

you have the links correct ?

 

[Justme]

you have the links correct ?

Initially no twidling control.
With one AVR I tried to play but full range did not affect output at all.

Pins all correct.

Just been out to tinker.

It seemed to be sensing at the 110 tap to the main N.

I know so do it that way but just to see I put it L1 to N.

Voltage now 160-260v ac with no loads.

I get the feeling its a diode issue or internal short.

 

[Anguz]

i assume you have this ?

https://www.generatorsolutions.no/images/manualer/Stamford_SX460.pdf

if its sensing 110v have you the link fitted ? on 3 and 4?
if its wanting to see 240 volt and only seeing 110, then it will be giving it more output

the 460 is normally pretty bombproof

 

[Justme]

It was fitted with no link but on the 110 side when it was working.

Then X happened & V went 333v ac.

3 AVr's all the same.
Moving sense wires to L1 & N (ie 240v) reduces v to 160-260 unstable.
Yes got that pdf thanks

 

[Anguz]

so have you twiddled the stability?

 

[Justme]

so have you twiddled the stability?

No, as it was stable before I am still looking for a physical fault rather then trying to band aid it at this stage.

 

[Anguz]

But if you have changed the avr for a new one then the stability pot will need tweaking

 

[MoreWellie]

I really doubt it is this but....

have you checked your meter on normal mains? I really doubt it will be wrong but....

 

[Justme]

But if you have changed the avr for a new one then the stability pot will need tweaking

The current avr is one of the old ones. Plus having fitted a few over the years they all seem ok out the box.

 

[Justme]

I really doubt it is this but....

have you checked your meter on normal mains? I really doubt it will be wrong but....

Normal mains? Whats that?


Offgrid so inverter or genny only.

Plus the inverter chargers wont accept crap in either.

 

[Onoff]

Duff capacitor sent mine whacky.

 

[the snooper]

Is the engine at the correct rpm, also what frequency is it showing

 

[Justme]

Has

Duff capacitor sent mine whacky.

Avr so no capacity.

 

[Justme]

Is the engine at the correct rpm, also what frequency is it showing

Engine was at correct rpm.
To be honest did not check when voltage was all over.

Planning on a day looking at it tomorrow.

 

[the snooper]

Carbon brushes ?, does the resistance of each winding read as it should ?, insulation test with avr disconnected.
It has to be something mentioned in this whole thread

 

[Justme]

Carbon brushes ?, does the resistance of each winding read as it should ?, insulation test with avr disconnected.
It has to be something mentioned in this whole thread

No brushes
all the windings read correctly.
None are direct shorted but I have not done an insulation breakdown test with a megga.


Pulled it apart yesterday.
Diodes all ok.
all windings are ok, meter correctly & no signs of burning.
no shorts or high resisitance joints.

planning on putting it all back together today ready for a new avr arriving in next day or two.