First, when operating a disconnecting switch, always check that the circuit breaker of the corresponding circuit is indeed in the open position to prevent operating the disconnecting switch under load.
When de-energizing or energizing a line, disconnecting switches must be operated in the correct sequence. During de-energization, the circuit breaker must be operated first, followed by the line-side disconnecting switch, and then the bus-side disconnecting switch. The energization sequence is the reverse of the de-energization sequence. This is because following this sequence can minimize the scope of the accident in case of misoperation, preventing it from escalating to the busbar.
During operation, if severe defects such as severely damaged insulators or severely damaged disconnecting switch transmission rods are found, operation must not be performed.
When operating a disconnecting switch, on-duty personnel should check each phase on-site for its open/closed position, synchronization, contact depth, etc., to ensure the disconnecting switch operates correctly and is in the correct position.
Disconnecting switches should generally be operated from the main control room. When remote electrical control fails, manual or electric operation can be performed on-site, but only with the permission of the station manager or technical supervisor and under on-site supervision.
Electrical, electromagnetic, and mechanical interlocking devices are installed between disconnecting switches, grounding switches, and circuit breakers to prevent misoperation. Switching operations must be performed in sequence. If the interlocking device malfunctions or the disconnecting switch and grounding switch cannot operate normally, the corresponding circuit breaker and disconnector positions must be strictly checked according to the interlocking requirements. Only after verification can the interlocking be released and operation carried out.