DCM621BC comprehensive motor anti-shake tester is specially developed for the contactor to actively release and the motor to stop when the grid is shaken. It absorbs the comprehensive advantages of re-excitation type and holding type. When the module is working normally, it adopts the “series” with the control loop. When the module is abnormal, the control loop is normally closed and enters the re-excitation mode, which has the advantages of strong compatibility, high reliability, anti-shake recording, and flexible installation.