Valve electric actuators have special requirements, that is, they must be able to limit torque or axial force. Usually, valve electric actuators use torque limiting couplings. After the specification of the electric actuator is determined, its control torque is also determined. Generally, it runs within a predetermined time and the motor will not overload. But if the following situations occur, it may lead to overload: firstly, the power supply voltage is low and the required torque cannot be obtained, causing the motor to stop rotating; The second is to mistakenly set the torque limiting mechanism to exceed the stopping torque, causing continuous excessive torque generation and causing the motor to stop rotating; The third is intermittent use, which generates heat accumulation that exceeds the allowable temperature rise of the motor; Fourthly, due to some reason, the circuit of the torque limiting mechanism malfunctions, resulting in excessive torque; The fifth reason is that the operating environment temperature is too high, which relatively reduces the thermal capacity of the motor.