Generator fault finding

[Robotstar5]

Hyundai generator has run fine for 4 years (serviced annually) powering lighting, kettle etc. at the stable then last week lost output voltage completely, normally it would point to a failed AVR, but a few hours online research makes me wonder if it's the rotor at fault?.

Generator with test points marked (AVR disconnected for tests)

VAC readings were as follows:
1 - 2 6V, 3 - 4 6V, 1 - 4 12V, and 5 - 6 18V

From what I have read/watched, anything over 10V across brushes (5 - 6) points to a duff rotor? brushes and slip rings are in good condition. A failed rotor would make repairs uneconomical so any advice or more tests to carry out would be appreciated.

Section of circuit diagram

Cheers.

 

[piman]

Hello Robotstar,

lift the brushes and do a resistance check of the rotor winding. I couldn't even begin to guess what sort of reading you want but it will tell if it's open circuit. Also a megger check of the rotor would be useful, just make sure no other components are connected when meggering the rotor.
Another test is to apply an exterior supply (6v D.C. ?) to the rotor sliprings when running to see if there is an output.

 

[Robotstar5]

OK, I will check resistance, although if I am getting 18V out of the brushes with nothing else connected there must be some sort of continuity through the winding?

Just got to wait until Friday when I can get there

 

[angellonewolf]

had a generator with no output after seaching on line for a few days (and if im remembering right) i was told to use a car battery through the brushes contacts (again if i remenber right take good note not to mixup the postive and negative terminals )

when you appy the power to the brush contacts this bypass the avr what should show a voltage on the volt meter on your generator the volts it shows should be about half of what it should be because the brushes normaly take 24volts to get the 240 out

please take this as info but im sure im right in say is right but just get someone to confirm it before blowing your gen up

when i did mine i wanted to test it would output something to confirm it was just the avr that was at fault as my gen was a cheap china copy so spending £15 was not a fortune but if not working could not recoupe any of the cost in selling 2nd hand if it was not the avr

there are a lot of china copys of the avrs and are normaly quite good as a lot have ajustable voltage so you only have to get one thats close to yours and use the ajustment for a final output but remember to get the measurements right on your avr so it will fit

measure the mounting holes and all dimensions on the box its self



when i rung around a few supplyer and said it a china one all i got was throw it away dont bother rubish £15 later a lot of time and it was working used it a few times myself for a few jobs needed doning then floged it and made a small pocket of folding stuff and used it for nothing

 

[Robotstar5]

Thanks, I'll do some research on applying voltage to the the exciter field windings

 

[angellonewolf]

try this said what i posted