Starting reactors are particularly used in the current limiting reactor of the large motor partial voltage starter, it connects in series with the three phase windings of the three phase asynchronous motor, that is, each winding of the reactor together with the each phase winding of the motor forms the Y-connection or D-connection way. When start the motor, the reactor was put in, the starting current which limit the motor is in the appropriate values, and at that moment, ciruit impedence is small, and the current is big, the starting current is five times of the rated current, and the voltage mainly on the reactors, after the finish of the starting, in order to improve the power factor, the reactor is removed, the motor supply the voltage to the normal rated voltage. Usually the reactors are core reactors, and the design of the starting reactor allow it continously operates for 2 minutes, and then it starts again for the need of cooling 4h. It should be point when giving the order if the starting scope is beyond the above.