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Generator Field Suppresion Contactors

Generator Field Suppresion Contactors

Generator Field Suppresion Contactors

(OP)
I am retrofitting a new excitation system to a 1MVA generator.  The existing one has a field suppression contactor on it.  I don't see the need.  Does anyone have an opinion in this

RE: Generator Field Suppresion Contactors

Suggestions:
1. Check with the generator manufacturer for its need to keep it
2. It depends what kind of retrofit/upgrade will be installed. It just may cover the function of the field suppression contactor, perhaps electronically
3. It beneficially functions during internal faults of the generator. See Reference:
Say M. G., "Alternating Current Machines," John Wiley & Sons, New York, 1978, page 430 "Field Suppression"

RE: Generator Field Suppresion Contactors

Is there a field breaker or contactor provided with the upgrade?  If yes, then normal design practice would use a "b" contact of the field switch to switch in a field discharge resistor.  Of course, the purpose of this is to de-excite the field in the minimum time to remove the fault current source from the system.

RE: Generator Field Suppresion Contactors

(OP)
Is there any substantial difference to removing the supply to the AVR which feeds a pilot excitor which feeds the main field to shorting out the main field using a contact of the CB.  Note there is no manual excitation only the AVR

RE: Generator Field Suppresion Contactors

Suggestion: The short-circuited main field will have some current circulating in it; therefore, it will behave as a rotating magnet generating some stator voltage and power.

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