When the parallel units start up and run, the first oil engine to reach a stable state will be connected to the bus through the generator circuit breaker. At this time, the corresponding grounding contactor of the oil unit should be closed at the same time. When any one of the six grounding contactors is closed, the rest of the contactors should remain disconnected.
When the contactor fails to close or the ground contactor fails to close, the contactor should be disconnected. At the same time, the vacuum contactor corresponding to any on-line oil engine in the system should be closed to ensure that only one neutral point of the generator set in the system is grounded by the resistor at a certain time.