Effect of corona and vibration on insulation of high voltage motor coil
Long-term high-voltage motors are subject to electromagnetic vibration, high temperature and high voltage. They are subject to mechanical wear due to electromagnetic vibration, corona corrosion and insulation aging due to heat generation, causing the overall insulation of the motor coil to be unshelled. Defects such as delamination, cauterization, wear and reduced dielectric strength eventually lead to insulation breakdown. Ms. Join us today to briefly talk about the effects of corona and vibration on coil insulation.
1, corona damage to the motor windings
In the operation of the high-voltage motor, the coil insulation is subjected to a high electric field strength. If the anti-halation layer (high, low resistance band or anti-corona paint) of the insulating surface is in poor contact with the stator core, the coil will vibrate in the groove and wear and insulate. Surface anti-halation layer. At this time, the insulating surface has a higher potential to the iron core, and corona discharge is generated at the worn portion, causing local instantaneous high temperature, and the main insulation of the coil and other auxiliary insulating materials are cauterized and burnt.
Corona discharge can also produce a chemical reaction with strong destructive force, which severely corrodes the insulation and coil wires, so that a large amount of green powder is collected in the severely corroded parts. In addition, the anti-halation treatment at the end of the winding is not good, which will cause the capacitor current to be too large, causing the stator end winding to generate heat, and accelerating the end winding insulation heat aging corrosion.
2, motor vibration damage to winding insulation
The vibration of the motor includes mechanical vibration and electromagnetic vibration. The various vibrations of the motor in operation will wear and corrode the insulation of the coil. The most important one is the influence of electromagnetic vibration on the winding and notch of the motor end.
●If the quality of the stator core is not good, the winding end is not well tied, and the immersion effect is poor, the coil will be vibrated due to poor fixing in the groove, and the interlayer gasket and the temperature measuring element strip will be up and down. Displacement between the layer coils wears the coil, which damages the coil insulation.
● If the current through the wire during the coil operation produces 2 times the electromagnetic vibration force, not only will the coil and the core and the winding end spacers vibrate, the main insulation surface will wear, and the wire will be between the main insulation and the main insulation. Frictional vibration occurs between the turns and the strands of the wires, causing the turns of the wires, looseness between the strands, short circuits, and strand breaks.
If an insulation short circuit occurs. Additional losses and temperature rises are generated in the short-circuited portion, which accelerates the local main insulation aging, reduces the insulation strength, and even causes insulation breakdown failure even under normal operating voltage.
