What is the primary function of the 43M switch on an EHV breaker?

The 43M switch, commonly referred to as the "breaker control switch," serves a crucial role in controlling and indicating the status of high-voltage circuit breakers. Its primary function is to provide operators with the ability to monitor the status of the breaker, whether it is open or closed, and allows them to perform local operations such as manually closing or opening the breaker when necessary. This capability is vital for safety and efficient operation in substations, as it ensures operators can quickly assess and manage the circuit breaker’s functionality on-site.

In addition to its control features, the indication of the breaker's status enhances operational awareness and ensures that all personnel are informed of the electrical system conditions, which is crucial for safety and maintenance procedures. The combination of status indication and local operation makes the 43M switch an essential component in managing the electrical equipment effectively.