I have 30KVA genset, when i turn it on, the voltage between two phases is very low about 30V, so i did the following test:

I tested all the windings (Main stator and rotor, exciter stator and rotor) they are all good.

the exciter stator contains all the magnets.

the rectifier diodes are all good, as well as the surge supressor.

I assume that the speed of the Diesel engine is good, (well, i don't have the tools to check it).

so, i thought that the AVR is faulty, i bought another one of the same firm.
But the problem is: when i supplyed the two AVRs at home with the same AC input they gave the same output ! i didn't place the new AVR in the genset yet.

I would like to know, how to test an AVR , how to know if it's faulty without placing it in the genset ?

thanks a lot for your answers in advance.

 

I have 30KVA genset, when i turn it on, the voltage between two phases is very low about 30V, so i did the following test:

I tested all the windings (Main stator and rotor, exciter stator and rotor) they are all good.

the exciter stator contains all the magnets.

the rectifier diodes are all good, as well as the surge supressor.

I assume that the speed of the Diesel engine is good, (well, i don't have the tools to check it).

so, i thought that the AVR is faulty, i bought another one of the same firm.
But the problem is: when i supplyed the two AVRs at home with the same AC input they gave the same output ! i didn't place the new AVR in the genset yet.

I would like to know, how to test an AVR , how to know if it's faulty without placing it in the genset ?

thanks a lot for your answers in advance.

Hello
you said that there are magnets in the exciter stator.
This is where there should be a coil that supplies a varying field to control the output voltage.
If the magnetic field from the magnet is small and just enough to start the alternator out putting voltage.
at that point the AVR should start regulating the exciter coil .
Do you have any info you can post?

 

Hello
you said that there are magnets in the exciter stator.
This is where there should be a coil that supplies a varying field to control the output voltage.
If the magnetic field from the magnet is small and just enough to start the alternator out putting voltage.
at that point the AVR should start regulating the exciter coil .
Do you have any info you can post?

Well, i replaced the AVR and the gen set worked perfectly. I guess, the problem is that the response of the old AVR wasn't fast enough.