Cause and treatment of winding damage of the hotte

  • Detail

Why is the winding of asynchronous motor damaged and how to deal with it

phase failure operation

1 Fault phenomenon

the motor cannot be started. Even if it can be started without load, the speed slowly rises and there is a buzzing sound; The motor emits smoke and heat, accompanied by a burning smell

2. Inspection results

remove the motor end cover, and you can see that 1/3 or 2/3 of the polar winding at the end of the winding is scorched or turns dark brown

3. Fault cause and treatment method

(1) the fuse circuit of the motor power supply circuit is in poor contact or is mechanically damaged, resulting in the fusing of a phase

(2) the three-phase fuse specifications of motor power supply circuit are different, and the fuse with small capacity burns out. The fuse with the same specification shall be replaced according to the power of the motor

(3) the contacts of the switches (disconnectors, rubber cover switches, etc.) and contactors in the rebate of Jinan experimental machine in the motor power supply circuit are in poor contact (burns or looseness). Repair and adjust the dynamic and static contacts to make them contact well

(4) a phase of the line is missing. Find out the broken line and connect it firmly

(5) faulty welding between motor winding wires leads to poor contact. Carefully check the connecting wire of motor winding and weld it firmly

overload operation

1 Fault phenomenon

the motor current exceeds the rated value; The temperature rise of the motor exceeds the rated temperature rise

2. Inspection results

all three groups of windings of the motor were burnt out; The bearing is free of grease or the sand frame is damaged; The stator and rotor cores rub against each other, commonly known as sweeping the bore

3. Fault causes and treatment methods

(1) when the load is too heavy, it is necessary to consider appropriate load reduction or replacement of motors with appropriate capacity

(2) if the power supply voltage is too high or too low, it is necessary to install a three-phase power supply voltage stabilization compensation cabinet

(3) the motor is seriously damp or corroded by corrosive gas for a long time, and the insulation resistance decreases. Overhaul or replace the enclosed motor with the same capacity and specification according to the specific situation

(4) the bearing is lack of oil, dry grinding or the rotor machinery is not concentric, causing the motor rotor to sweep the bore, so that the motor current exceeds the rated value. First of all, carefully check the bearing wear. If it is unqualified, replace it with a new bearing; Secondly, clean the bearing and inject an appropriate amount of grease. Then check the motor end cover. If the rotor is not concentric due to wear of the center hole of the end cover, the end cover should be treated or replaced

(5) the transmission part of the mechanism fails, causing the motor to overload and burn out the motor winding. Check the faults of the mechanical part and take measures to deal with them to make them rotate flexibly

winding grounding

1 Fault phenomenon

Electrical zigzag fatigue experiment can be divided into Rotating Zigzag fatigue experiment, circular zigzag fatigue experiment and plane zigzag fatigue experiment; It can also be divided into 3-point zigzag, 4-point zigzag and cantilever zigzag. The fatigue testing machine cannot be started without load; The fuse of motor power supply circuit is blown or the switch trips

2. Inspection results

the stator notch winding and iron core have burn marks and copper melting point; Breakdown of winding and core in the slot; The insulation of the outer skin of the winding outgoing line is damaged

3. Fault causes and treatment methods

(1) when repairing the motor, the bamboo wedge was inserted carelessly, causing the insulation of notch winding to be damaged; The bamboo wedge is aging with poor insulation. High quality bamboo wedges shall be selected according to the motor off-line process, and insulation treatment shall be done well. Be careful not to scratch the wire with the bamboo wedge when going offline

(2) for motors that are exposed to moisture for a long time or work in corrosive gases, they should be replaced with enclosed motors

(3) the winding insulation of open motor is damaged due to metal or metal chips entering the motor. For this, protective plates or plates should be added around the motor

(4) the rotor balance block is loose or falls off, scraping the insulation of the motor winding. The balance weight should be reoriented and fixed, and the damaged part of the winding should be handled

(5) if there is no lightning arrester or the lightning arrester fails, the lightning arrester should be added or recalibrated

winding phase to phase short circuit

1 Sichuan gonggaxue new material officially landed on the new third board Fault phenomenon

the motor cannot be started; Fuse of motor power supply circuit is blown or switch trips; The motor winding is smoking and has a burning smell

2. Inspection results

the strands of wires at the phase to phase short circuit are burnt out, and there is a copper melting point around them

3. Fault cause and treatment method

(1) for the motor with scratched insulation on the surface of the conductor or poor insulation at the end of the winding of the "three-step" strategy when it is offline, the burned conductor should be picked up, cleaned, welded, wrapped and flattened, brushed with insulating paint and dried after entering the slot. If it cannot be repaired, rewind according to the original data

(2) the bushing of the connecting wire between windings and the reference wire must match the insulation grade of the motor winding, and the insulating bushing of the connecting wire should be 15 ~ 25mm longer than the welding point

winding turn to turn short circuit

1 Fault phenomenon

the motor smokes during operation, the local temperature rise is too high, and there is a burning smell

2. Inspection results

the three-phase current of the motor is unbalanced; Several turns or one coil becomes bare wire

3. Fault cause and treatment method

(1) when several turns or a coil are burnt out, if the slot full rate is not high, it can be repaired by threading

(2) see Item 4 for the rest

finding and quickly eliminating electrical equipment faults in time can prevent accidents and ensure the smooth progress of production. In this regard, it is necessary to regularly inspect and maintain electrical equipment according to regulations, accurately judge and deal with the operation faults of electrical equipment, reduce equipment accident losses, and ensure normal production

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