The rated power of the selected motor should be equal to or slightly greater than the calculated power. In addition, the most commonly used analogy method is to select the power of the motor. Analogy method. That is to compare with the power of motors used in similar production machines. The specific method is: to understand the unit or other similar units of similar production machinery use more power motor, and then choose a similar power motor test run. The purpose of the test run is to verify whether the selected motor matches the production machine. Validation of the method is: the motor drives the production machine, working current clamp meter measuring the motor, comparing the current rating marked the measured current and the motor nameplate. If the actual working current of the electric power machine is similar to that of the rated current on the mark, the power of the selected motor is suitable. If the actual working current of the motor is about 70% lower than the rated current on the nameplate, it is indicated that the power of the motor is too large, and the motor with smaller power should be replaced. If the measured motor current is greater than 40% of the rated current on the nameplate, it is indicated that the power of the motor is too small, and the motor with larger power should be replaced. In fact, torque (torque) should be considered, and the power and torque of the motor are calculated. That is, T = 9550P/n type: P - power, kW; N - motor rated speed, r/min; T - torque, Nm. The output torque of the motor must be greater than the torque required by the working machine. Generally, a safety factor is needed.