Turn-to-turn short circuit occurs in the motor winding, the following phenomena will occur:
1) A large circulating current (usually 2-10 times the normal current) will flow through the short-circuited coil, which will cause the coil to heat up severely;
2) The three-phase current is unbalanced, and the motor torque is reduced;
3) Generate noise;
4) When the short circuit is serious, the motor cannot start with load.
Turn-to-turn short circuit initially may only have two wires touching due to worn insulation at the overlap.
Due to the circulation current in the short-circuited wire turns, the coil heats up rapidly, which further damages the insulation of the adjacent wires, so that the number of short-circuited turns continues to increase and the fault expands.
When the number of short-circuit turns is large enough, the fuse will be blown, and even the winding will burn and smoke.
When there is an inter-turn short circuit in one phase of the three-phase winding, it means that the number of turns of the winding in this phase decreases, and the three-phase current of the stator is unbalanced. The unbalanced three-phase current makes the motor vibrate and make abnormal sound at the same time.
The average torque of the motor drops significantly, and it becomes weak when dragging the load.
1) A large circulating current (usually 2-10 times the normal current) will flow through the short-circuited coil, which will cause the coil to heat up severely;
2) The three-phase current is unbalanced, and the motor torque is reduced;
3) Generate noise;
4) When the short circuit is serious, the motor cannot start with load.
Turn-to-turn short circuit initially may only have two wires touching due to worn insulation at the overlap.
Due to the circulation current in the short-circuited wire turns, the coil heats up rapidly, which further damages the insulation of the adjacent wires, so that the number of short-circuited turns continues to increase and the fault expands.
When the number of short-circuit turns is large enough, the fuse will be blown, and even the winding will burn and smoke.
When there is an inter-turn short circuit in one phase of the three-phase winding, it means that the number of turns of the winding in this phase decreases, and the three-phase current of the stator is unbalanced. The unbalanced three-phase current makes the motor vibrate and make abnormal sound at the same time.
The average torque of the motor drops significantly, and it becomes weak when dragging the load.
Reasons for inter-turn short circuit of motor winding
1) Poor manufacturing process. For example: inter-turn insulation is damaged during off-line, shaping and other processes; hard blocks and burrs on copper wires will also cause inter-turn insulation damage.
2) During operation, under the action of comprehensive stresses such as electricity, heat and machinery, the windings are deformed and displaced, causing inter-turn insulation to break, wear, and fall off; in addition, due to dirt, etc., it may also cause inter-turn (especially rotor between the ends of the windings) short circuit.
3) Long-term operation and aging insulation will also cause inter-turn short circuit.
