What should V/Hz protection trip?

[veritas]

Should the V/Hz function in a generator protection relay trip the GCB, FCB, master fuel and turbine or only the GCB and FCB? I have an application where only the GCB and FCB are tripped but another where it hits all 4. Both are for 660MW units.

Thanks.

 

[ScottyUK]

It's an electrical problem, so I would expect to trip both the generator and field breakers but leave the turbine running. Better to have a controlled shutdown than a proetction trip.