Two New Methods for Direct Measurement of Induction Motor Slip-Tracking Rotation Method and Complementary Rotation Method

Two new methods for direct measurement of induction motor slip are presented. Both of them are based on the fact that the slip, which is indicated by the rotation of the image in a speciel mark disc located on the motor shaft under the shine of daylight lamp, can be translated onto the shaft of another auxiliary servomoter. This makes it possible to directly and accurately measure the slip by tachometer without weary in vision of testers.