Inventory The Phenomenon That May Occur in The Short Circuit Between Turns Of The Motor Winding A Short Circuit Occurs Between Turns in The Motor Windings

Inventory the phenomenon that may occur in the short circuit between turns of the motor winding

A short circuit occurs between turns in the motor windings

 

If a short circuit occurs between turns in the motor winding, the following phenomena will occur.

1) The short-circuited coil will flow through a large circulation current (often 2-10 times the normal current), causing the coil to seriously heat;

2) The three-phase current is unbalanced, and the motor torque is reduced:

3) Produce noise;

4) When the short circuit is serious, the motor cannot be started with the load.

 

Inter-turn short circuit: At the beginning, only two wires may come into contact due to insulation wear at the overlap.

Due to the circulation generated in the short circuit turn, the coil heats up rapidly, further damaging the insulation of the adjacent wire, so that the number of turns of the short circuit continues to increase and the fault expands.

 

When the number of short circuit turns is enough, the fuse will be burned, and even the winding will be scorched and smoked, when the three-phase winding has a phase of inter-turn short circuit, it is equivalent to the phase winding number of turns reduced, the stator three-phase current is unbalanced. The three-phase current of the uneven street makes the motor vibrate, and at the same time emits abnormal sound explosion-proof cloud platform.

 

The average torque of the motor drops significantly, and it appears weak when dragging the load.

 

The cause of short circuit between turns of the motor winding

 

1) Poor manufacturing process. For example: damage to inter-turn insulation in the process of off-line, shaping and other processes: copper wire has hard blocks and burrs, which will also cause inter-turn insulation damage.

2) During operation, under the action of electrical, thermal and mechanical comprehensive stresses, the windings are deformed and displaced, resulting in breakage, wear and fall off of the insulation between turns: in addition, due to dirt, etc., it may also cause short circuits between turns (especially between the ends of the rotor winding).

3) Long running and aging insulation will also cause short circuits between turns.

 

Motor winding inter-turn short circuit treatment method

 

When a short circuit occurs in the winding, it will usually be manifested as a fuse of the motor power supply circuit or a trip of the switch; When the motor winding is short-circuited, a large current is generated and the coil heats up quickly and burns out. So that there will be a burning taste; uneven distribution of magnetic fields; The current imbalance makes the motor vibrate or aggravate the noise generated during operation, and even make the motor unable to operate normally. In the event of a short circuit, we can deal with it by the following methods

 

1. Induction method >>

 

This method is to use the principle of electromagnetic induction to put a special short-circuit transformer-short-circuit detector across the stator increase, after the short-circuit detector is energized, if the iron sheet placed on the notch vibrates, it means that there is a short circuit phenomenon.

 

2 Observational >>

That is, observe whether the end of the winding and the insulation inside the trunking are damaged or burned, and whether there is a peculiar smell.

 

3 multimeter or megohmmeter inspection method >>

That is, use these two tables to test the insulation resistance between any two-phase winding, and the reading is very little or zero, then there is a phase-to-phase short circuit.

 

4. Detection temperature check method >>

Make the motor run without load for a certain period of time, and touch the temperature of each part of the winding by hand whether it is normal, if there is a short circuit between turns, then the temperature of this place will generally be relatively high.

 

5 Energization test method >>

This is a fairly simple method, that is, to test with a current meter, if there is a short circuit between the phases, the current through is generally relatively large. The above are the most common treatment methods, and we explain them with examples below.

 

When a winding short circuit occurs, the method should be screened according to the actual situation and corresponding measures should be taken to deal with it.