Analysis of common faults in electric motors

Source: China Bearing Network Time: 2013-01-06

/*250*250 was created on 2017/12/25*/ var cpro_id = 'u3171089';

Three-phase asynchronous motor is widely used; but after a long period of operation; various problems will occur; timely identification of the cause of the disease; corresponding disposal; is to avoid the expansion of the disease; to ensure the normal operation of the equipment.
1. After the power is turned on, the motor can't be changed; but there is no abnormal noise; there is no smell or smoke.
1. The cause of the problem is that the power supply is not connected (at least two phases are not available),
2 fuse is blown (at least two phases are blown),
3 overcurrent relay has been adjusted.
4 control equipment wiring fault.
2. Fault sweep 1 check the power loop switch; can there be a breakpoint at the fuse and junction box;
2 Check the fuse type, fuse edge; replace the fuse,
3 conditioning relay setting value and motor cooperation,
4 correct the wiring.
Second, the motor does not turn after power-on; then the fuse is blown
1. The cause of the disease is 1 lack of a phase power supply; or the fixed dry coil is reversed,
2 stator windings are short-circuited between phases,
3 stator windings are grounded,
4 stator winding wiring fault,
5 fuse cross section.
6 power line short circuit or ground.
2. Sweeping 1 to see if the knife gate can have a phase is not good; the power circuit can have a phase break, eliminating the reverse fault,
2 detect the short circuit point; correct it,
3 eliminate the address.
4 detect misconnection; correct it,
5 replace the fuse,
Third, the motor does not turn after the power is turned on.
l. The cause of the problem is 1 fixed, the rotor winding has an open circuit (one phase disconnection) or the power supply loses phase.
2 The winding lead wire is connected at the wrong end or the winding is internally reversed.
3 power circuit contacts are loose; touch resistance is large,
4 motor load is too large or the rotor card.
5 power supply voltage is too low,
6 small motor installation is too tight or the grease inside the bearing is too hard,
7 bearing stuck.
2. Sweeping 1 to find out the breakpoint to be corrected,
2 Check the winding polarity; determine whether the winding end is correct,
3 Fasten the loose connecting screws; use a multimeter to judge whether the joints can be connected; correct them,
4 load shedding or detecting and eliminating mechanical problems,
5 Check that the ruled face connection method is also mistakenly connected to Y; can the voltage drop be too large because the power supply wire is too thin; correct it,
6 from the beginning to make it sensitive; replace the qualified grease,
7 correction bearings.
Fourth, the motor is difficult to start; when the load is extra; the motor speed is lower than the extra speed
1. The cause of the problem is that the power supply voltage is too low.
The 2-sided connection motor is misconnected to Y,
3 cage rotor is open welded or cracked,
4 The rotor part of the rotor is misconnected and reversed.
5 When the motor winding is corrected, too many turns are added.
6 motor overload.
2. Sweeping 1 to measure the power supply voltage; try to improve,
2 correct the connection,
3View the open welds and breakpoints and correct them.
4Detect the misconnection; correct it,
5 rehabilitation is correct,
6 load shedding.
5. The motor no-load current is unbalanced; the three-phase phase difference is large.
1. When the cause is 1 rewinding; the number of turns of the stator three-phase winding is not equal,
2 winding the first end of the winding is wrong,
3 power supply voltage is unbalanced,
4 windings have inter-turn short circuit, coil reverse connection and other problems.
2. Sweeping 1 to make a sub-winding from the head,
2 view and correct,
3 measure the power supply voltage; try to eliminate the imbalance,
4 steep removal of winding problems.
Sixth, the motor is unloaded; when the load is overloaded; the ammeter pointer is unstable;
1. The problem is that the cage rotor strip is welded or broken.
2 winding type rotor fault (one-phase open circuit) or brush, collector ring short circuit device bad touch.
2. Trouble sweeping 1 to detect broken strips to correct or replace the rotor,
2 View the rotor loop and correct it.
Seven, the motor no-load current balance; but the value is large
1. When the cause is corrected by 1; the stator winding turns are excessively cut,
2 The power supply voltage is too high,
3Y connected to the motor is incorrectly connected to Î”,
4 The motor is installed; the rotor is reversed; the stator core is not aligned; the useful length is shortened,
5 air gap is too large or uneven,
6 overhaul when removing the old winding; use the hot-break method is not appropriate; the core is burned.
2. Sweeping 1 winding around the stator winding; rehabilitation is correct,
2 try to recover the extra voltage,
3 changed to Y,
4 installed from scratch,
5 replace the new rotor or adjust the air gap,
6 Check the iron core or calculate the winding from the beginning; add the appropriate number of turns.
Eight, the sound is not normal when the motor is running; there is abnormal noise
1. The cause is that the rotor is rubbed with the stator insulation paper or the wedge.
2 bearing wear or foreign matter such as sand in the oil,
3 fixed rotor core loose,
4 bearings are short of oil,
5 air duct packing or electric fan wiper;
6 fixed rotor core rubbing,
7 The power supply voltage is too high or unbalanced.
8 stator windings are staggered or shorted.
2. Sweeping 1 trimming insulation; cutting the wedge,
2 replace the bearing or remove the bearing,
3 inspection and repair, rotor core,
4 Come on,
5 finishing the airway, from the equipment,
6 eliminate scratches; if necessary, the small rotor inside the car,
7View and adjust the power supply voltage,
8 eliminate the stator winding problems.
Nine, the motor oscillation is larger during operation
1. The cause of the problem is 1 because the wear bearing gap is too large,
2 the air gap is not uniform,
3 rotor imbalance,
4 twists and turns,
5 iron core is deformed or loose,
6 Couplings (pulleys) are not proofread in the middle,
7 electric fan is not balanced,
8 casing or base strength is not good,
9 motor foot screw is loose,
10 cage rotor open welding, open rotor winding, plus stator winding fault.
2. Fault sweep 1 repair bearing; replace if necessary,
2 adjust the air gap; make it even,
3 proofreading rotor dynamic balance,
4 straight shaft,
5 proofreading stacked iron cores,
6 proofreading from the beginning; make it conform to the rules,
7 repair the fan; proofreading balance; correct its shape,
8 for reinforcement,
9 fasten the foot screws,
10 Correct the rotor winding and correct the stator winding.
Ten, bearing overheating
1. The cause of the disease is too much or too little.
2 oil is not good enough, rich in impurities,
3 bearing cooperation with the journal or end cap is not appropriate (too loose or too tight),
4 bearing inner hole is painful; rubbing against the shaft,
5 motor end cover or bearing cover is not flat,
6 The motor and load coupling are not proofed; or the belt is too tight,
7 bearing gap is too large or too.
8 motor shaft twists and turns.
2. Sweeping 1 according to the rule plus smooth grease (1/3-2/3 of volume),
2 replace the hygienic smooth grease,
3 too loose with the binder can be corrected; overtightening the car; grinding the journal or end cap inner hole; make it suitable,
4 repair the bearing cover; eliminate the rubbing point,
5 installed from scratch,
6 proofread from the beginning; adjust the belt tension,
7 replace the new bearing,
8 proof the motor shaft or replace the rotor.
11. The motor is overheated and even smokes.
1. The cause of the problem is that the power supply voltage is too high;
2 The power supply voltage is too low; the motor is running with additional load; if the current is too large, the winding will heat up.
3 when repairing and removing the winding; it is not appropriate to use the hot-break method; burn the iron core,
4 fixed rotor core rub,
5 motor overload or frequent start,
6 cage rotor broken bars,
7 motor phase loss; two phases running,
8 rewinding is not enough for the winding immersion paint,
9 high ambient temperature, the motor has more dust on the outside; or the air duct is blocked.
10 motor fan problem; poor ventilation, stator winding problems (interphase, interturn short circuit, internal winding fault of the stator winding).
2. Faulty sweep 1 drop power supply voltage (such as adjusting the power supply transformer tap); if the motor Y, Î” connection fault is caused; then the connection should be corrected,
2 improve the power supply voltage or change the thick power supply wire,
3 overhaul the iron core; remove the fault,
4 eliminate the rubbing point (adjust the air gap or setback, the car rotor),
5 load shedding, control the start according to the number of rules,
6 view and eliminate rotor winding problems,
7 rehabilitation three-phase operation,
8Select secondary dipping paint and vacuum dipping process,
9Clear the motor; improve the ambient temperature; use the cooling method,
10 View and correct the fan; replace if necessary, repair the stator winding; eliminate the problem.

Recommend to friends comments close window

Bearing related knowledge

Rolling bearing technical information in two major aspects of the selection of imported bearings mechanical seal layout of imported bearings classification and series analysis of the fan bearing fault cause and sweeping device and replacement bearing skills

This article links to http://
Please indicate the bearing network http://

Previous:The reason and countermeasures of cracking of bearing ring: The sliding bearing is suitable for high speed and heavy load

Router Bit

Router Bit,Profiling Wheel,Granite Profiling Wheel

Diamond Segment,Diamond Saw Blade,Diamond Wire Saw Co., Ltd. , http://www.nsblades.com