Features are showed as following1, protecting electric motor and improving ability of the electric motor2, shortening the period of startup; reducing average electric current during the starting process3, lessening shock and vibration in startup proven ting overload4, balacing loads of each motor in multi-motor drive system5, Simple reliable structure. No mechanical wear. No need for special maintenance. Application:Belt conveyor. AFC conveyor, Chain conveyor, Screw conveyor, Excavators, Bucker wheel. Excavator. Bucket conveyor. Grinding mill. Crusher Coal planer. Tower crane. Grantry crane. Bridge crane. Blender equipment. Centrifuger. Washer. Leather-marking machine. Machine for recreation park mixer wire drawing machine. Extruder. Dregs crusher of boiler.