Winding short-circuit due to excessive electrical current, supply voltage change is too large, single-phase operation, mechanical bumps which break the  insulation. There are four types, inter-turnshort circuit, winding short-circuit, winding pole short-circuit and winding phase short circuit.

    1. Fault phenomenon

    As the three-phase current imbalance caused by uneven distribution of the stator magnetic field, so that the motor run-time increased vibration and noise, seriously motor could not be started, and in the short-circuit coil generated a big short-circuit current, resulting in rapid heating and the motor burned.

    2. Cause

    Long-term operation of motor overload caused loss of insulation 

    inlay line insulation damage insulation 

    damage insulation caused by damp 

    layers insulation damaged

    cable insulation damaged

    insulation damaged by lightning

    damage caused by friction between stator and rotor

    foreign bodies falling into the motor

    3. Examination

    one, external observation. Judging by if the terminal box ,end winding, winding overheating left dark brown and a bad smell.

    Two,Bridge inspection. DC winding resistance should not exceed more than 5%, the phase with small resistance may be short-circuit fault.

    Three,Megohm meter or multimeter. if the arbitrary two-phase winding insulation resistance is verysmall or zero, indicating that the two-phase windings are short-circuit phase.

    4. Short-circuit approach

    One,Short-circuit in the end. Insulating materials can be used to separate short-circuit point, packets may also be re-insulated wire, and then re-drying paint.

    Two,Short-cut occerd in line bed. After softening to identify short-circuit point ,repair it and put it in line bed , and then drying paint.