Abstract：Three-phase asynchronous motor is one of the most frequently used motors. Inter-turn short circuit

fault is a kind of fault with high probability. If the real-time monitoring of motor operation，health and safety

evaluation of the operation，will be able to timely stop losses，reduce losses. An inter-turn fault diagnosis method

was proposed based on extended Clarke transform and fault characteristic factor Q，analyzed the characteristics of

Clarke vector of inter-turn fault of motor，modulated the Clarke vector of inter-turn fault of motor，and obtained the DC component of symmetrical component and the AC component twice the fundamental frequency in the threephase current. The ratio of the amplitude of the component to the DC component was used as the fault characteristic factor Q to diagnose the inter-turn fault. Clarke vector spectrum was studied by characteristic factor Q，so as to judge the motor fault，and theoretical simulation and prototype test were carried out.

      Key words：three-phase induction motor；inter-turn short circuit fault；Clarke vector；characteristic factor Q