two generators 10.5 kV are connected to a bus bar(33 kV) through block delta/star transformers 10.5 / 33 kv the star side is earthed through 250 ohm
a circuit breaker is installed at the 10.5 and 33 kV sides
One generator was in operation (i.e 10.5 and 33 kV breakers closed)
the other generator was stand by (10.5 kV breaker opened while 33kV breaker closed)
An earth fault occured on the busbar and the in operation Generator sensed the fault and tripped the 33 and 10.5 breakers.
The question is: for the stand by generator, it also sensed the fault and tripped the 33kV breaker, why?
does this have a relation to the fact that the block transformer at the 33kV side is star and earthed. please explain?