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

1. #1Birken Vogt2017-07-07 23:32

   That is the model of the engine but it does not tell anything about the generator. What kind of generator is this on?

2. #2alaa2017-07-08 23:54

   Thanks for reply the generator LS Leroy Somer

3. #3Birken Vogt2017-07-09 00:37

   Leroy Somer Model number?

4. #4alaa2017-07-09 17:39

   Leroy Somer Model number RPES2 by FG wilson

5. #5Birken Vogt2017-07-10 15:40

   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.

6. #6spark2017-07-11 07:19

   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.

7. #7alaa2017-07-16 19:07

   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.

8. #8Birken Vogt2017-07-17 11:42

   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?

9. #9spark2017-07-17 15:14

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

10. #10Birken Vogt2017-07-17 15:22

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

11. #11alaa2017-07-17 21:47

    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...

12. #12Birken Vogt2017-07-17 21:59

    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.

13. #13alaa2017-07-17 22:54

    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....

14. #14Birken Vogt2017-07-17 23:47

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

15. #15alaa2017-07-18 23:01

    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