Fault and maintenance of high voltage squirrel cage three-phase asynchronous motor
A high-voltage motor is a motor that operates at a power frequency of 50 Hz, a rated voltage of 3 kV, a 6 kV, and a 10 kV AC three-phase voltage. There are various classification methods for high-voltage motors, ranging from small to medium-sized, large-sized and extra-large in size; from A, E, B, F, H, and C motors in terms of insulation class; General-purpose high-voltage motors and high-voltage motors with special structures and applications.
The motor to be described in this paper is a general-purpose high-pressure squirrel-cage three-phase asynchronous motor.
The high-voltage squirrel-cage three-phase asynchronous motor is built on the basis of electromagnetic induction. Under the action of high electromagnetic field and its own technical conditions, external environment and operating conditions, the motor will be generated within a certain period of operation. Various electrical and mechanical failures.
1 high voltage motor often fails
1.1 Motor insulation resistance is low, winding insulation breakdown grounding and lead-out failure
Due to the humid environment, the insulation of the motor is damp, and the insulation resistance value does not meet the requirements of the regulations; due to the large dust, magnetic substances fall on the surface of the coil, causing drilling phenomenon, causing the insulation of the stator winding to be broken through to ground; the motor lead position is at The hot air area on the back of the iron core is insulated and heat aged after long-term operation. The rubber insulation of the lead wire is crispy, deteriorated and peeled off. The external force and mechanical vibration cause the porcelain bottle to rupture or the motor lead is loose, resulting in poor contact or even breakage of the motor lead wire and severe arc discharge. .
1.2 Motor stator slot wedge loose, end banding fault failure
The stator wedge of the motor is loose and the end of the winding is not properly tied. When the motor starts to vibrate during starting and running, the coil is relatively displaced, and the electromagnetic noise of the motor is large, and a discharge phenomenon occurs.
1.3 Motor rotor failure
The effects of thermal effect force, electromagnetic force and mechanical centrifugal force generated during frequent and overloaded operation of the motor cause alternating stress, which causes the short-circuit ring of the motor squirrel-cage rotor to be welded to the copper strip weld, and the rotor copper strip is loosened in the groove. The stator current swing is large, the motor vibration is severe, the electromagnetic sound of the motor increases and the discharge phenomenon occurs.
1.4 motor bearing failure
The bearings are not installed correctly, the tolerances are too tight or too loose, and the grease is not properly added. During operation, the bearing heats up, the temperature rise is too high, the vibration is large, and the sound at the bearing is abnormally loud.
