We have 4 generators running in parallel out of which one is always in isochronous mode. Suddenly one generator other than isochronous generator tripped in rotor earth fault which was soon followed by tripping of iso generator by a earth fault relay. and soon due to cascade tripping there was a black out condition. I want to know why the isochronous generator tripped in earth fault.

pls guide me

 

Trust the bus is grounded. Please check.


Then if an isochronous unit trips then another should be made isochronous. If a good load sharing system is in place no need to do anything.