Disconnection faults in the control circuit of 10 kV switchgear can easily cause circuit breakers to fail to trip or close

seriously threatening power grid security and power supply reliability. Taking the VS1 type withdrawable circuit breaker as the research object

this paper analyzes the principle of control circuit disconnection

identifies major causes such as damage to trip and closing coils

abnormalities in the spring charging circuit

auxiliary switch faults

and loose wiring

and proposes a systematic troubleshooting method that proceeds from external to internal components in descending order of fault probability. In addition

a convenient measuring point selection scheme based on PCB wiring is provided

offering technical support for maintenance personnel to rapidly handle faults.