In view of the mis-opening and closing accident of a 1000 kV isolating switch during the local opening after the motor being burnt during the closing process

it analyzes the problems in the application range of auxiliary contacts in different time sequence and the control circuit of isolation switch with single-phase linkage and separate phase operation.It proposes solutions to strengthen the requirements of the isolating switch control circuit

clarify the action timing of the auxiliary contacts of the isolating switch

optimise the relationship between the self-holding control circuit and the motor power circuit

and standardise the operational processes of maintenance personnel

ensuring the safe and stable operation of the isolating switch

providing a reference for the circuit design and operation maintenance of similar isolating switches.