Frequent breakdown occurs for control contactor in 500 kV disconnecter, due to the transient arc surge appearing in the coil circuit at the moment of excitation return, by analyzing the voltage and current waveforms during the operation of control contactor. Therefore, the anti-accident measures are proposed by applying the arc suppression circuit to the control contactor coil. By comparing the effect of two kinds of arc suppression circuit, an arc suppression circuit with the diode and series resistance is selected.