The Causes And Inspection Methods Of Motor Winding Short Circuit Fault Are Analyzed

Winding as an important component of the motor, is the motor when used to convert electrical energy into mechanical energy important components, although it is protected by the casing in the center of the motor, but the winding will also fail, mainly due to motor current is too large, power supply voltage fluctuation is too large, single-phase operation, mechanical bumps and other reasons. The short circuit fault of the motor winding will affect the normal operation of the motor and is a fault with greater harm to rotating equipment.

Motor winding faults can be divided into: winding inter-turn short circuit, winding short circuit, winding pole short circuit and winding phase short circuit.

 

 

Above: Motor burned out by a short circuit in the windings

 

If the reason is unknown and the handling is not done properly, it will often be half the effort. It will reduce the service life of the motor, increase maintenance costs, and even cause the winding to burn out.

 

Therefore, quickly judging the cause of the winding short circuit fault and taking appropriate measures to solve it is the guarantee for the continuous and safe operation of the equipment. Today, Shenghua Motor sorted out the data and inventoried the causes and maintenance methods of motor winding short circuit faults for everyone.

 

1. Fault symptoms

 

The magnetic field distribution of ions is uneven, the three-phase current is unbalanced and the vibration and noise of the motor are aggravated, and the motor cannot be started when it is serious, and a large short-circuit current is generated in the short circuit circle, resulting in rapid heating of the coil and burning.

2. Cause

 

The motor looks like a tailor weaving greening the life of the family to make the absolute aging big go to the extinct household; Insulation damage caused by wire embedding; The winding is moisture-cooled and the insulation resistance decreases, resulting in insulation breakdown; The end and interlayer insulation materials are not properly cushioned or damaged when shaping: the end connection wire insulation damage: overvoltage or lightning strikes to break down the insulation; The rotor and the stator winding end rub against each other and cause insulation damage; Metal foreign matter falls into the inside of the motor and excessive oil stain.

3. Check the method

 

(1) External observation method. Observe whether the end of the junction box and winding is burned, and the winding leaves dark brown color and odor after overheating.

(2) Temperature detection and inspection method. Run without load for 20 minutes (stop immediately when an abnormality is found), and use the back of your hand to feel whether each part of the winding exceeds the normal temperature.

(3) Energization experiment method. Measured with an ammeter, if the current of a phase is too large, it means that the phase has a short circuit.

(4) Bridge inspection. Measuring the DC resistance of a winding, the general phase difference should not exceed 5%, if it exceeds, the resistance is small

One phase has a short-circuit fault.

(5) Short circuit detector method. If there is a short circuit in the winding to be tested, the steel sheet will vibrate.

(6) Multimeter or megohmmeter method. Measure the insulation resistance between the phases of any two-phase winding, if the reading is very small or zero, it means this There is a short circuit between the phases of the two-phase winding.

(7) Voltage drop method. After connecting the three windings in series, a low-voltage safe alternating current is connected, and a short circuit fault is measured in the group with small reading.

(8) Current method. When the motor runs without load, the three-phase current is measured first, and the two-phase is measured and compared in exchange, if not adjusted with the power supplyIn turn, the one-phase winding with a larger current has a short circuit.

 

4 .Short circuit treatment method

 

TU-6
(1) The short circuit point is at the end. The short-circuit points can be separated by insulating materials, and the insulated wires can also be repackaged, and then painted and dried.

(2) Short circuit in the line groove. After softening it, find the short circuit point to repair, put it back into the trunking, and then paint and dry.

(3) For each phase winding with a short route turn of less than 1/12, cut all the new short routes when the number of divisions is connected in series, and connect the conduction part

Closed circuit is formed for emergency use.

(4) When the number of turns of the winding short circuit point exceeds 1/12, all should be removed and rewound.