I changed 3 times AVR I need the root cause of the problem

[alaa]

Hi,
I have changed 3 AVR on Perkins Generator 2306C-E14 (FGB061018U4412K) after explosion or burnt
each one 2 to 3 weeks ....I need the root cause of the problem ....
Thanks Eng's in advance...

 

[Birken Vogt]

That is the model of the engine but it does not tell anything about the generator.

What kind of generator is this on?

 

[alaa]

Thanks for reply
the generator LS Leroy Somer

 

[Birken Vogt]

Leroy Somer Model number?

Thanks for reply
the generator LS Leroy Somer

 

[alaa]

Leroy Somer Model number RPES2 by FG wilson

 

[Birken Vogt]

That looks like the FG wilson number, not the number of the Leroy Somer alternator...and we have nothing like that FG Wilson unit over here near as I can tell.

Have you tried discussing it with FG Wilson?

Otherwise try and find the Leroy Somer model on the alternator itself.

 

[spark]

My experience this happens when the exciter field becomes shorted. The only load of the AVR is the exciter field. I have had numerous times with failures and the only cure was an exciter field (exciter stator) replacement.

 

[alaa]

Thanks gents,
I attached to the name plate of engine and alternator ... about the resistance of exciter stator was 11 Ohm
now it's running at 50% of load with direct connection of 12VDC for more than 10 day's with out AVR.
Still with out any solution.

 

[Birken Vogt]

That exciter resistance sounds a little bit low. I can't find what the specification is supposed to be on this model, though. Also, did you check exciter stator for grounds?

 

[spark]

Look under leroy-somer.comdocumentation-pdf4455_en.pdf for that type it shows 12.5 ohms exciter field resistance

 

[Birken Vogt]

Assuming the field is not grounded or intermittently shorted, I would next try an aftermarket voltage regulator and see if it behaves any differently.

 

[alaa]

Thanks gents
Exciter not grounded I'm not sure the value ... but let me guess that was to ground 14 K ohm or more....
Is there any relation with back power to the neutral cable...

 

[Birken Vogt]

http://www.leroy-somer.com/documentation_pdf/4455_en.pdf

Another thought, it might be a rotating diode failed. This would cause the AVR to work harder for the same output.

If I recall, it is a lot of work but you might be able to reach in and disconnect the individual terminals from the rotating rectifier and test the diodes individually on this model.

 

[alaa]

I did not test the diodes ... but it will fail and show up 0 Volt from the beginning when I start the genset even with the direct 12 DCv,like it is now working by 12 DCv supply....

 

[Birken Vogt]

So you are saying sometimes it will not work even with 12 VDC applied? But usually it does?

 

[alaa]

No ... bro ... Now the generator working with 12Vdc applied with out AVR and and working fine with load around 40% from rated Kw ...I wish it will not damage the alternator ....
I will not give up