Maintenance of the hottest wire wound asynchronous

Maintenance of wire wound asynchronous motors

our factory is a medium-sized chemical enterprise, with more than 80 motors in the factory, among which the motor models jr137-8 and jr158-8 are the most. Due to the aging of the equipment and frequent failures in recent years, the motor runs R2 - the ring pressure strength of the inner paper (n/0.152m); When there is spark in the rotor, the reading of the ammeter increases, causing the thermal relay to act. The motor cannot operate normally, which seriously affects normal production

1 fault phenomenon

it is understood that in recent years, the motor often shows inability to drive the mechanical part to operate, and the rotor part continuously produces sparks. After that, the relay acts to shut down, and it is verified that the Y-point connection of the motor rotor is broken, resulting in shutdown for repair. Each failure is sent to Shenyang electric machinery factory for maintenance, which takes a long time and affects the continuity of production

2 cause analysis

shear fracture occurs in the direction of about 45 degrees after bearing a great force. After repeated observation and exploration, the causes can be used for parallel multi bubble method determination and analysis as follows:

(1) some machines are aging, and the start and operation are often overloaded to form the phenomenon of high current and high temperature

(2) there are signs of abrasion on the large and small gears of the grinding cylinder driven by the reduction gearbox, which produces relatively large vibration during operation

(3) affected by the vibration of the reducer, the coupling and coupling rubber have different degrees of abrasion

(4) there are no other fixed points at rotor y point except the connection point

based on the above reasons, the Y-point fracture of the mill motor rotor should be caused by the coupling introducing the mechanical vibration of the load part to the Y-point, resulting in the fracture of the connection between the motor rotor coil and the Y-point

3 improvement ideas

the root cause of the fracture at the connection between Y-point and rotor is vibration, and the mutual stress caused by vibration is borne by the three connections between Y-point copper ring and rotor coil, so we set up multiple fixed points of Y-point copper ring. So as to share the stress at the joint, which can greatly reduce the stress at the joint and prevent the fracture at the joint

4 improvement method

from August 2001, the Y-point of five motor rotors was improved respectively:

(1) lift the end cover of the Y-point connecting end of the mill motor to expose the whole Y-point of the rotor

(2) take a piece of 100mm × 20mm copper plate, drill a 5mm small hole at both ends, lock the connection between the rotor coil and the Y-point copper ring with screws, and add tin to connect closely

(3) drill a 10mm screw hole on each of the four symmetrical points of the rotor core

(4) 50mm × Four 20mm copper plates are drilled at both ends in I-shape, one end is fixed on the symmetrical 4 points of the rotor core, and the other end is vertically fixed with the copper ring at the Y point

5 effect

after more than one year of production practice, the improvement of Y-point of five motor rotors has achieved remarkable results, basically eliminating this fault, and the cost is only 30 yuan/set, and the transformation time is only about half a day. This also saves a large amount of delivery and repair costs, and eliminates the production discontinuity caused by motor failure, so that the enterprise reduces undue losses. (end)