electric generator field breaker 2

[nauj4321]

When a 3 phase electric generator is on line (generator using rotating brushless exciter), is it advisable or necessary to underexcitate the generator in order to open the field breaker, before opening the Circuit breaker?. Also is it advisable to provoke negative excitation?

 

[3winding]

Nauj4321,

It is common in AVR circuits to have a free wheeling diode or blocking diode to protect against the collapsing field of the generator when the unit is taken off line.

When you mentioned negative excitation are you referring to under excited, or absorbing VARS from the system? Check the generator capability curve for your machine. This will show where you can safely run the unit without overheating or stability problems.

Pintalo

 

[jbartos]

Suggestion: Please, follow the generator manufacturer instruction manual or check with the generator manufacturer tech support. Experimenting with the larger generator operation is not exactly a good idea.

 

[nauj4321]

Dear Mr. Pintalo & jbartos(Electrical) Mar 24, 2004
It is common in AVR circuits to have a free wheeling diode or blocking diode to protect against the collapsing field of the generator when the unit is taken off line.

When I mentioned negative excitation I was referring to inverted pulse, of couse we operate the generator under the capability curve. Because this is important for safely run the unit without overheating or stability problems.


Thank pintalo & jbartos, for this valuable post!

 

[jbartos]

Comment on the original posting: The field circuit breaker is not designed for switching purposes. It is designed for protection of the excitation circuit. Opening of the filed circuit breaker is not supposed to be prerequisite for opening of generator circuit breaker.
The generator excitation is supposed to be automatic. Why to provoke the negative excitation?
Is there a generator operation exam pending?