Abstract: Various startup modes and operation characteristics of asynchronous motor were introduced. The damage caused by direct startup of crusher motor was analyzed. The reformation scheme with soft starter was adopted. The reformed crusher control system has many advantages, such as improving the torque and startup characteristics of the motor, reducing the startup current, decreasing the shock to the power system by the motor starting, lengthening the service life of the crusher and enhancing the utilization factor of the equipment.

Key words: asynchronous motor, soft starter, programmable logic controller, motor comprehensive protector