SASHmash
Electrical
- Jan 17, 2007
- 4
I am currently having the problem that an earth fault on my motor (LV) is tripping out my MCC rather than isolating the fault to that particular motor, by locally tripping the motor. The obvious cause is that the fault grading is incorrect. However, at this particular sub station we use a CB with a very sensitive earth fault protection relay (integral protection). The protection on the motor cannot be adjusted to trip on a lower fault as this causes the motor to trip under normal operating conditions. A suggested approach is to replace the integral protection on the CB and integrate these relays with the old CB. This is quite a costly and laborsum approach, as is replacing the circuit breakers. Any ideas?