The existing re-start cabinet with PLC as the core has high cost and complicated wiring. The single-machine re-start relay only relies on the bus voltage where the motor is located and the position of the auxiliary contact of the contactor to identify the loss of power, and requires auxiliary power supply, so the probability of re-start failure is high. Shi Yong, a senior engineer in this paper, introduces a method for restarting motors (groups) when they lose power, which is realized in the motor protection device. It can reliably distinguish the shaking current from the normal shutdown, with precise logic and flexible setting of fixed value. It supports restarting motors with various control modes without increasing wiring and cost. The method has been applied in petrochemical enterprises, and it can operate correctly in many times of shaking.