generator voltage

[jalover]

Hi, i need some advice, we have generator rated 300 kw , 440 v 60 hz, brushless type. when we start eh generator it only gives 50 volts from the main terminal instead of 440 v, avr have changed already, rotating rectifier changed also, all meggered ok. but same result. freq is ok. any other thought? thanks a lot.

 

[mls1]

A few questions:

1. Have you measured the voltage applied to the stationary exciter field?

2. Is the 50V you measured consistent line-to-line across all three phase configurations?

I'm wondering if you are not measuring residual voltage from rotor remnant magnetization and your exciter field is not actually being applied.

 

[ScottyUK]

Connect a variable DC power supply - 30V / 2A or so would be ideal - in place of the AVR output and gradually bring the voltage up from zero. What happens? Can you measure current into the field winding?



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If we learn from our mistakes I'm getting a great education!

 

[waross]

Check the frequency with a known good meter. A lot of gen-sets have poor quality frequency meters. A cheap capacitor failing in the meter internal circuit will result in erroneous readings. Some of the cheap meters are sensitive to low voltage also.

Bill
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"Why not the best?"
Jimmy Carter