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Prevention of incorrect opening/closing of circuit breakers:

• Mechanical interlock: The operating handle must be inserted into a specific position and operated in sequence, directly restricting incorrect opening/closing.

• Electrical interlock: The closing circuit of the circuit breaker is connected in series with the auxiliary contact of the disconnector. Closing is prohibited if the disconnector is not fully closed.

Prevention of load-breaking operation of disconnectors:

• Mechanical interlock: The operating mechanisms of the circuit breaker and disconnector are locked by a mechanical linkage. The disconnector cannot be operated when the circuit breaker is closed.

• Electrical interlock: The operating circuit of the disconnector is connected in series with the normally closed auxiliary contact of the circuit breaker. The circuit is disconnected when the circuit breaker is closed, prohibiting disconnector operation.

Prevention of grounding switch closing (or grounding wire installation) on live circuits:

• Mechanical interlock: The operating mechanism of the grounding switch is mechanically interlocked with the cable chamber door. The door cannot be opened to install grounding wires when the cable chamber is live.

• Electrical interlock: The closing circuit of the grounding switch is connected in series with the contact of the live-line indicator. Closing is prohibited when the circuit is live, as the circuit is disconnected.

Prevention of circuit breaker closing with grounding switch engaged (or grounding wire installed):

• Mechanical interlock: The operating mechanisms of the grounding switch and circuit breaker are mechanically interlocked. The circuit breaker cannot be closed when the grounding switch is engaged.

• Electrical interlock: The closing circuit of the circuit breaker is connected in series with the normally closed auxiliary contact of the grounding switch. Closing is prohibited when the grounding switch is engaged, as the circuit is disconnected.

Prevention of unauthorized access to live compartments:

• Mechanical interlock: The switchgear door is interlocked with the operating mechanisms of the disconnector and grounding switch. The door cannot be opened when the compartment is live.

• Electrical interlock: The electromagnetic lock circuit of the door is connected in series with the live-line indicator contact. The electromagnetic lock is energized to lock the door when the compartment is live.