it is a New invention in national field of changing load motor compensation control. Accurate compensation according to actual loading situation range of application It applicable for 75kw--10000kw wound rotor asynchronous motor reactive power local compensation and power save. especially for places where always working in changing-load condition. Adopt double CPU control and adjusting the related parameters according to changing load , realize dynamic compensation and make power factor in optimal state all the time decrease the stator current and winding temperature rising, improving power factor and efficiency, to reduce the loss of the motor and power system. characteristic increase motor power factor to over 0.95---0.99; reduce reactive power more than 60% reduce motor stator current 10-20%; save line loss and copper loss 20-30% independent working system from motor, can adjust and maintenance without stop the motor Automatic tracking rotor current ,for constant torque load and changing torque load with function of malfucntion record, over current, low voltage, less phase, outer fault, communication failure, parameter mistake protetion Friendly man-machine interface, LCD screen interface , simple operation, with reliable and all-round automatic fault protection function without influence on production in paintenance and take-care . can take back the cost within half a year environment temperatue: -40C---+50C relative humidity of air no exceed 90%