Select the correct motor power is very important. Such as the use of the motor when power is less than the required work machine power, the motor will overload fever, even with no action industry machinery, resulting in "small horse cart" phenomenon, affecting the life of the motor, and even burned the motor. The motor power selection is too large, since the motor efficiency and power factor drops, the circuit is not running the economy, the emergence of "big horse car" phenomenon, resulting in waste of power and money. Therefore selected motor power should be slightly larger than the power required for operating machinery, general work than to be driven mechanical power preferably about 10% larger, so that the motor has a short-term overload. Mechanical power required by the job description check on the work machine. As the specification is missing when the required power can not be found, you can first use a larger power motor driven work machine, and then to measure the motor driving the work machine when the electric power consumed by the meter or power meter, measured electric power value is the work required work machine power.