Practical method in motor repair
2 Finding and processing grounding points in the stator winding slot
Grounding in the stator winding slot generally occurs in the slot. Because the slot insulation paper is biased or damaged in the slot, or the indentation is inadvertently placed in the slot, the enameled wire is placed under the slot insulation paper, or the slot insulation paper is crushed when the slot wedge is driven. Causes a ground fault.
For such a fault, it is first necessary to determine whether the motor winding is damp. If it is wet, the motor is baked. If the result is invalid, it is judged to have a ground fault.
The methods for finding the grounding point are as follows:
1. Carefully check the lead wires and the two ends of the slot. It is found that the lead wires are intact, and the slots at both ends of the slot are not damaged. The inside and outside of the motor are clean and there is no dust or oil everywhere. This means that the grounding point is in the slot.
2. Untie the Y-connection point of the stator winding, measure the relative insulation resistance of each stator, and find the phase with ground fault.
3. With a single-phase voltage regulator, the phase line at the output end is connected to the one end lead line with the ground fault phase, the zero line is connected to the motor casing, and then the voltage regulator is boosted from zero to the tank. Tobacco, this is to immediately turn the regulator output voltage to zero and cut off the power supply, the smoke is the grounding point. Pay attention to safety throughout the operation. Place the motor on an insulating mat. The human body cannot touch the motor before the power is cut off.
The treatment method is as follows: carefully remove the wedge with the grounding groove, then heat the motor into the oven, bake the soft winding, and carefully remove the inner wire of the groove to check the insulation of each wire. If the insulation is damaged, paint and dry it, then place the groove insulation paper in the groove again, then put the removed wire into the groove, punch into the groove wedge, and dip the paint and dry the winding.
If it is found that the enameled wire has been blown, pull the two broken wires to the end of the winding, and then find a wire with the same wire diameter into the groove and wire at both ends of the winding. The joint should be stranded, painted, dried, and then covered with an insulating sleeve. When strapping the ends, pay attention to the binding joints.
