How to operate high voltage disconnector and circuit breaker in parallel?

First, check whether the disconnector is grounded (grounding knife, grounding wire), then close the line-side disconnector with power supply, then close the load-side disconnector (if any), and finally close the circuit breaker. This is because the disconnector has no protection and no arc extinguishing ability, so it should be closed before the circuit breaker is connected to the circuit. The circuit breaker has protection device and arc extinguishing ability. Once close to the fault circuit, the protection of the circuit breaker will open the circuit immediately. Therefore, the circuit breaker is finally used as a closed circuit.