When the motor is running or malfunctions, it can be prevented and eliminated in time by four methods of watching, listening, smelling, and touching to ensure the safe operation of the motor.
one look
Observe whether there is any abnormality during the operation of the motor, which is mainly manifested in the following situations.
1. When the stator winding is short-circuited, the motor may see smoke.
2. When the motor is severely overloaded or lacks phase, the speed will slow down and there will be a heavy "buzzing" sound.
3. The motor runs normally, but when it suddenly stops, you will see sparks at the loose connections; the fuse is blown or a part is stuck.
4. If the motor vibrates violently, the transmission device may be stuck, the motor may be poorly fixed, or the foot bolts may be loose.
5. If there are discoloration, burn marks and smoke marks on the contact points and connections in the motor, it may indicate that there may be local overheating, poor contact at the conductor connection or burnt winding.
Second, listen
The motor should emit a uniform and light "buzzing" sound during normal operation, without noise and special sounds. If the noise is too loud, including electromagnetic noise, bearing noise, ventilation noise, mechanical friction sound, etc., it may be a precursor to failure or a phenomenon.
1. For electromagnetic noise, if the motor emits a loud and heavy sound, the reasons may be as follows.
(1) The air gap between the stator and the rotor is not uniform. At this time, the sound is suddenly high and low and the interval between the high and low bass is unchanged. This is caused by bearing wear and the stator and rotor are not concentric.
(2) The three-phase current is unbalanced. This is the cause of erroneous grounding, short circuit, or poor contact in the three-phase winding. If the sound is very dull, it means that the motor is seriously overloaded or lacks phase operation.
(3) The iron core is loose. When the motor is running, the iron core fixing bolt is loosened due to vibration, which causes the iron core silicon steel sheet to loosen and emit noise.
2. For bearing noise, it should be monitored frequently during motor operation. The monitoring method is: put one end of the screwdriver against the bearing installation part, and the other end close to the ear, you can hear the running sound of the bearing. If the bearing is operating normally, its sound is a continuous and small "rustle" sound, there will be no sudden high and low changes and metal friction sound. If the following sounds appear, it is abnormal.
(1) There is a "squeak" sound when the bearing is running. This is the sound of metal friction. It is generally caused by the lack of oil in the bearing. The bearing should be disassembled and filled with an appropriate amount of grease.
(2) If there is a "chirp" sound, this is the sound made when the ball rotates. It is generally caused by the dryness of the grease or the lack of oil. You can add a proper amount of grease.
(3) If there is a "click" or "creak" sound, it is the sound caused by the irregular movement of the balls in the bearing. This is caused by the damage of the balls in the bearing or the long-term use of the motor and the dryness of the grease.
3. If the transmission mechanism and the driven mechanism emit continuous sounds instead of flickering, they can be divided into the following situations.
(1) The periodic "pop" sound is caused by the unevenness of the belt joint.
(2) The periodic "dongdong" sound is caused by the looseness between the coupling or the pulley and the shaft and the wear of the key or keyway.
(3) The uneven collision sound is caused by the fan blades colliding with the fan cover.
3. Smell
It is also possible to judge and prevent malfunctions by smelling the smell of the motor. If a special paint smell is found, it means that the internal temperature of the motor is too high; if a heavy paste smell or burnt smell is found, the insulation layer may be broken or the windings have been burned.
Four, touch
You can also determine the cause of the fault by touching the temperature of some parts of the motor. To ensure safety, the back of the hand should be used to touch the motor housing and the surrounding parts of the bearing when touching it. If the temperature is found to be abnormal, the reasons may be as follows.
1. Poor ventilation. Such as the fan falling off and the air duct blocked.
2. Overload. The current is too large and the stator winding is overheated.
3. Short circuit between turns of stator winding or unbalanced three-phase current.
4. Frequent start or brake.
5. If the temperature around the bearing is too high, the bearing may be damaged or lack of oil.
Failure analysis and elimination of three-phase asynchronous motor
Three-phase asynchronous motors are widely used, but after a long period of operation, various failures will occur, and the cause of the failure will be judged in time to deal with it accordingly. This is an important task to prevent the expansion of the failure and ensure the normal operation of the equipment.
1. The motor cannot rotate after being energized, but there is no abnormal noise, odor and smoke.
1. Causes of failure ① The power supply is not connected (at least two phases are not connected); ② The fuse is blown (at least two phases are fused); ③ The overcurrent relay is adjusted too small; ④ The wiring of the control equipment is wrong.
2. Troubleshooting ① Check the power circuit switch, whether there is a breakpoint at the fuse and junction box, repair; ② check the fuse type, the reason of the fuse, and replace the fuse; ③ adjust the relay setting value to cooperate with the motor; ④ correct the wiring.
2. The motor does not rotate after power on, and then the fuse is blown
1. Causes of failure ① lack of one-phase power supply, or reverse connection of fixed-drying coils; ② short-circuit between stator windings; ③ stator winding grounding; ④ stator winding wiring error; ⑤ cross-section of fuse is too small;
2. Trouble shooting ① Check whether there is a phase failure of the knife gate, but there is a phase disconnection in the power circuit; eliminate the reverse connection fault; ② find the short circuit point and repair it; ③ eliminate the grounding; ④ detect the wrong connection and correct it; ⑤ replace Fuse; ③ Eliminate the grounding point.
3. The motor does not turn and there is a buzzing sound after power on
l. Causes of failure ① The rotor winding is broken (one phase is broken) or the power supply is out of phase; ② The beginning and end of the winding lead wire are connected incorrectly or the internal winding is reversed; ③ The power circuit contact is loose and the contact resistance is large; ④ The motor is overloaded Large or the rotor is stuck; ⑤The power supply voltage is too low; ⑥The assembly of the small motor is too tight or the grease in the bearing is too hard;
2. Troubleshooting ① Identify the breakpoint and fix it; ② Check the polarity of the winding; determine whether the end of the winding is correct; ③ Tighten the loose wiring screws, use a multimeter to determine whether each joint is falsely connected, and repair it; ④ Reduce the load or find and eliminate Mechanical failure, ⑤ check is to mistakenly connect the specified surface connection method to Y; whether the voltage drop is too large due to the power wire is too thin, correct it, ⑥ reassemble to make it flexible; replace qualified grease; ⑦ repair the bearing.
4. It is difficult to start the motor. When the rated load, the motor speed is more than the rated speed
1. Causes of the fault ①The power supply voltage is too low; ②The face-connected motor is mistakenly connected to Y; ③The cage rotor is welded or broken; ④The local coil of the fixed rotor is wrongly connected or reversed; ③Too many turns are added when repairing the motor winding; ⑤The motor overload.
2. Troubleshooting ①Measure the power supply voltage and try to improve; ②correct the connection; ③check the welding and breakpoints and repair; ④detect the wrong connection and correct it; ⑤recover the correct number of turns; ⑥load reduction.
Fifth, the no-load current of the motor is unbalanced, and the three-phase difference
1. Causes of faults ①When rewinding, the number of turns of the three-phase stator winding is not equal; ②The winding ends are connected wrong; ③The power supply voltage is unbalanced; ④There are faults such as short-circuit between turns and reverse connection of the coil.
2. Troubleshooting ①Rewind the stator winding; ②Check and correct; ③Measure the power supply voltage and try to eliminate the unbalance; ④Clear the winding fault.
Sixth, the motor is no-load, when the load is overloaded, the ammeter pointer is unstable and swings
1. Causes of failure ①Cage-type rotor guide bar welding or broken bar; ②Wound rotor failure (one-phase open circuit) or poor contact of brush and collector ring short-circuit device.
2. Troubleshooting ① Find the broken bar to repair or replace the rotor; ② check the circuit around the rotor and repair it.
Seven, the motor no-load current balance, but the value is large
1. Causes of faults ①When repairing, the number of stator winding turns is reduced too much; ②The power supply voltage is too high; ③Y connected to the motor is wrongly connected to Δ; ④In the motor assembly, the rotor is reversed, the stator core is not aligned, and the effective length is shortened; ⑤ The air gap is too large or uneven; ⑥ When dismantling the old winding during overhaul, improper use of thermal dismantling method will burn the iron core.
2. Troubleshooting ①Rewind the stator winding and restore the correct number of turns; ②Try to restore the rated voltage; ③Reconnect to Y; ④Reassemble; ③Replace the new rotor or adjust the air gap; ⑤Repair the iron core or recalculate the winding and increase the number of turns appropriately number.
8. When the motor is running, the noise is abnormal and there is abnormal noise.
1. Causes of the fault ① The rotor rubs against the stator insulation paper or slot wedge; ② The bearing wears or there are foreign objects such as sand particles in the oil; ③ The fixed rotor iron core is loose; ④ The bearing lacks oil; ⑤ The air duct is stuffed or the fan wipes the hood, ⑥ The fixed rotor The iron core is rubbed; ⑦ The power supply voltage is too high or unbalanced; ⑧ Stator winding is misconnected or short-circuited.
2. Trouble shooting ①Pruning insulation, cutting down the slot wedge; ②Replace or clean the bearing; ③Repair and repair, rotor core; ④Lubricate; ⑤Clean the air duct; Reinstall the device; ⑥Remove scratches, if necessary, the small rotor in the car; ⑦ Check and adjust the power supply voltage; ⑧ Eliminate stator winding faults.
Nine, the motor vibration is large
1. Causes of failure ① The bearing clearance is too large due to wear; ② The air gap is uneven; ③ The rotor is unbalanced; ④ The shaft is bent; ⑤ The core is deformed or loose; ⑥ The center of the coupling (belt pulley) is not corrected; ⑦ The fan is unbalanced; ⑧ The strength of the shell or foundation is not enough; ⑨Motor foot screws are loose; ⑩Cage rotor open welding open circuit; winding rotor open circuit; plus stator winding failure.
2. Troubleshooting ①Repair the bearing and replace it if necessary; ②Adjust the air gap to make it even; ③Correct the rotor dynamic balance; ④Straighten the rotating shaft; ⑤Correct the overlapping iron core, ⑥Recalibrate to make it comply with the regulations; ⑦Repair the fan, correct Balance, correct its geometry; ⑧ reinforce; ⑨ tighten the anchor screws; ⑩ repair the rotor winding; repair the stator winding.
Ten, bearing overheating
1. Causes of failure ① Too much grease or too little grease; ② Poor oil quality containing impurities; ③ Improper fit of bearing and journal or end cap (too loose or too tight); ④ Bearing inner hole eccentric, rubbing against shaft; ⑤ Motor The end cover or bearing cover is not installed flat; ⑥ The coupling between the motor and the load is not corrected, or the belt is too tight; ⑦ The bearing gap is too large or too small; ⑧ The motor shaft is bent.
2. Troubleshooting ① Add grease as required (1/3-2/3 of the volume); ② Replace the cleaned grease; ③ If it is too loose, it can be repaired with adhesive, and if it is too tight, it should be turned by a car, and the journal or the inner hole of the end cap should be ground. To make it suitable; ④ repair the bearing cover and eliminate the rubbing points; ⑤ reassemble; ⑥ re-calibrate and adjust the belt tension; ⑦ replace the new bearing; ⑧ correct the motor shaft or replace the rotor.
11. The motor overheats or even smokes
1. Causes of failure ①The power supply voltage is too high, which greatly increases the core heating; ②The power supply voltage is too low, the motor is running with a rated load, and the current is overheated when the winding is heated; ③When the winding is repaired and removed, the thermal disassembly method is improper and burns the core; ④The fixed rotor iron core is rubbed; ⑤The motor is overloaded or frequently started; ⑥The cage rotor has broken bars; ⑦The motor lacks phase and two-phase operation; ⑧Insufficient varnish is set on the winding after rewinding; ⑨High ambient temperature Multiple, or blocked ventilation channels; ⑩ motor fan failure, poor ventilation; stator winding failure (phase, turn-to-turn short circuit; stator winding internal connection error).
2. Troubleshooting ① Reduce the power supply voltage (such as adjusting the tap of the power supply transformer), if the motor Y, Δ connection is wrong, you should correct the connection; ② increase the power supply voltage or replace the thick power supply wire; ③ repair the iron core, eliminate the fault; ④ Eliminate the rubbing points (adjust the air gap or frustration, car rotor); ⑤ reduce the load; control the start according to the specified number of times; ⑥ check and eliminate the rotor winding failure; ⑦ resume three-phase operation; ⑧ adopt the second dipping and vacuum dipping process; ⑨ Clean the motor, improve the ambient temperature, and adopt cooling measures; ⑩ Check and repair the fan, replace it if necessary; repair the stator winding to eliminate the fault.
one look
Observe whether there is any abnormality during the operation of the motor, which is mainly manifested in the following situations.
1. When the stator winding is short-circuited, the motor may see smoke.
2. When the motor is severely overloaded or lacks phase, the speed will slow down and there will be a heavy "buzzing" sound.
3. The motor runs normally, but when it suddenly stops, you will see sparks at the loose connections; the fuse is blown or a part is stuck.
4. If the motor vibrates violently, the transmission device may be stuck, the motor may be poorly fixed, or the foot bolts may be loose.
5. If there are discoloration, burn marks and smoke marks on the contact points and connections in the motor, it may indicate that there may be local overheating, poor contact at the conductor connection or burnt winding.
Second, listen
The motor should emit a uniform and light "buzzing" sound during normal operation, without noise and special sounds. If the noise is too loud, including electromagnetic noise, bearing noise, ventilation noise, mechanical friction sound, etc., it may be a precursor to failure or a phenomenon.
1. For electromagnetic noise, if the motor emits a loud and heavy sound, the reasons may be as follows.
(1) The air gap between the stator and the rotor is not uniform. At this time, the sound is suddenly high and low and the interval between the high and low bass is unchanged. This is caused by bearing wear and the stator and rotor are not concentric.
(2) The three-phase current is unbalanced. This is the cause of erroneous grounding, short circuit, or poor contact in the three-phase winding. If the sound is very dull, it means that the motor is seriously overloaded or lacks phase operation.
(3) The iron core is loose. When the motor is running, the iron core fixing bolt is loosened due to vibration, which causes the iron core silicon steel sheet to loosen and emit noise.
2. For bearing noise, it should be monitored frequently during motor operation. The monitoring method is: put one end of the screwdriver against the bearing installation part, and the other end close to the ear, you can hear the running sound of the bearing. If the bearing is operating normally, its sound is a continuous and small "rustle" sound, there will be no sudden high and low changes and metal friction sound. If the following sounds appear, it is abnormal.
(1) There is a "squeak" sound when the bearing is running. This is the sound of metal friction. It is generally caused by the lack of oil in the bearing. The bearing should be disassembled and filled with an appropriate amount of grease.
(2) If there is a "chirp" sound, this is the sound made when the ball rotates. It is generally caused by the dryness of the grease or the lack of oil. You can add a proper amount of grease.
(3) If there is a "click" or "creak" sound, it is the sound caused by the irregular movement of the balls in the bearing. This is caused by the damage of the balls in the bearing or the long-term use of the motor and the dryness of the grease.
3. If the transmission mechanism and the driven mechanism emit continuous sounds instead of flickering, they can be divided into the following situations.
(1) The periodic "pop" sound is caused by the unevenness of the belt joint.
(2) The periodic "dongdong" sound is caused by the looseness between the coupling or the pulley and the shaft and the wear of the key or keyway.
(3) The uneven collision sound is caused by the fan blades colliding with the fan cover.
3. Smell
It is also possible to judge and prevent malfunctions by smelling the smell of the motor. If a special paint smell is found, it means that the internal temperature of the motor is too high; if a heavy paste smell or burnt smell is found, the insulation layer may be broken or the windings have been burned.
Four, touch
You can also determine the cause of the fault by touching the temperature of some parts of the motor. To ensure safety, the back of the hand should be used to touch the motor housing and the surrounding parts of the bearing when touching it. If the temperature is found to be abnormal, the reasons may be as follows.
1. Poor ventilation. Such as the fan falling off and the air duct blocked.
2. Overload. The current is too large and the stator winding is overheated.
3. Short circuit between turns of stator winding or unbalanced three-phase current.
4. Frequent start or brake.
5. If the temperature around the bearing is too high, the bearing may be damaged or lack of oil.
Failure analysis and elimination of three-phase asynchronous motor
Three-phase asynchronous motors are widely used, but after a long period of operation, various failures will occur, and the cause of the failure will be judged in time to deal with it accordingly. This is an important task to prevent the expansion of the failure and ensure the normal operation of the equipment.
1. The motor cannot rotate after being energized, but there is no abnormal noise, odor and smoke.
1. Causes of failure ① The power supply is not connected (at least two phases are not connected); ② The fuse is blown (at least two phases are fused); ③ The overcurrent relay is adjusted too small; ④ The wiring of the control equipment is wrong.
2. Troubleshooting ① Check the power circuit switch, whether there is a breakpoint at the fuse and junction box, repair; ② check the fuse type, the reason of the fuse, and replace the fuse; ③ adjust the relay setting value to cooperate with the motor; ④ correct the wiring.
2. The motor does not rotate after power on, and then the fuse is blown
1. Causes of failure ① lack of one-phase power supply, or reverse connection of fixed-drying coils; ② short-circuit between stator windings; ③ stator winding grounding; ④ stator winding wiring error; ⑤ cross-section of fuse is too small;
2. Trouble shooting ① Check whether there is a phase failure of the knife gate, but there is a phase disconnection in the power circuit; eliminate the reverse connection fault; ② find the short circuit point and repair it; ③ eliminate the grounding; ④ detect the wrong connection and correct it; ⑤ replace Fuse; ③ Eliminate the grounding point.
3. The motor does not turn and there is a buzzing sound after power on
l. Causes of failure ① The rotor winding is broken (one phase is broken) or the power supply is out of phase; ② The beginning and end of the winding lead wire are connected incorrectly or the internal winding is reversed; ③ The power circuit contact is loose and the contact resistance is large; ④ The motor is overloaded Large or the rotor is stuck; ⑤The power supply voltage is too low; ⑥The assembly of the small motor is too tight or the grease in the bearing is too hard;
2. Troubleshooting ① Identify the breakpoint and fix it; ② Check the polarity of the winding; determine whether the end of the winding is correct; ③ Tighten the loose wiring screws, use a multimeter to determine whether each joint is falsely connected, and repair it; ④ Reduce the load or find and eliminate Mechanical failure, ⑤ check is to mistakenly connect the specified surface connection method to Y; whether the voltage drop is too large due to the power wire is too thin, correct it, ⑥ reassemble to make it flexible; replace qualified grease; ⑦ repair the bearing.
4. It is difficult to start the motor. When the rated load, the motor speed is more than the rated speed
1. Causes of the fault ①The power supply voltage is too low; ②The face-connected motor is mistakenly connected to Y; ③The cage rotor is welded or broken; ④The local coil of the fixed rotor is wrongly connected or reversed; ③Too many turns are added when repairing the motor winding; ⑤The motor overload.
2. Troubleshooting ①Measure the power supply voltage and try to improve; ②correct the connection; ③check the welding and breakpoints and repair; ④detect the wrong connection and correct it; ⑤recover the correct number of turns; ⑥load reduction.
Fifth, the no-load current of the motor is unbalanced, and the three-phase difference
1. Causes of faults ①When rewinding, the number of turns of the three-phase stator winding is not equal; ②The winding ends are connected wrong; ③The power supply voltage is unbalanced; ④There are faults such as short-circuit between turns and reverse connection of the coil.
2. Troubleshooting ①Rewind the stator winding; ②Check and correct; ③Measure the power supply voltage and try to eliminate the unbalance; ④Clear the winding fault.
Sixth, the motor is no-load, when the load is overloaded, the ammeter pointer is unstable and swings
1. Causes of failure ①Cage-type rotor guide bar welding or broken bar; ②Wound rotor failure (one-phase open circuit) or poor contact of brush and collector ring short-circuit device.
2. Troubleshooting ① Find the broken bar to repair or replace the rotor; ② check the circuit around the rotor and repair it.
Seven, the motor no-load current balance, but the value is large
1. Causes of faults ①When repairing, the number of stator winding turns is reduced too much; ②The power supply voltage is too high; ③Y connected to the motor is wrongly connected to Δ; ④In the motor assembly, the rotor is reversed, the stator core is not aligned, and the effective length is shortened; ⑤ The air gap is too large or uneven; ⑥ When dismantling the old winding during overhaul, improper use of thermal dismantling method will burn the iron core.
2. Troubleshooting ①Rewind the stator winding and restore the correct number of turns; ②Try to restore the rated voltage; ③Reconnect to Y; ④Reassemble; ③Replace the new rotor or adjust the air gap; ⑤Repair the iron core or recalculate the winding and increase the number of turns appropriately number.
8. When the motor is running, the noise is abnormal and there is abnormal noise.
1. Causes of the fault ① The rotor rubs against the stator insulation paper or slot wedge; ② The bearing wears or there are foreign objects such as sand particles in the oil; ③ The fixed rotor iron core is loose; ④ The bearing lacks oil; ⑤ The air duct is stuffed or the fan wipes the hood, ⑥ The fixed rotor The iron core is rubbed; ⑦ The power supply voltage is too high or unbalanced; ⑧ Stator winding is misconnected or short-circuited.
2. Trouble shooting ①Pruning insulation, cutting down the slot wedge; ②Replace or clean the bearing; ③Repair and repair, rotor core; ④Lubricate; ⑤Clean the air duct; Reinstall the device; ⑥Remove scratches, if necessary, the small rotor in the car; ⑦ Check and adjust the power supply voltage; ⑧ Eliminate stator winding faults.
Nine, the motor vibration is large
1. Causes of failure ① The bearing clearance is too large due to wear; ② The air gap is uneven; ③ The rotor is unbalanced; ④ The shaft is bent; ⑤ The core is deformed or loose; ⑥ The center of the coupling (belt pulley) is not corrected; ⑦ The fan is unbalanced; ⑧ The strength of the shell or foundation is not enough; ⑨Motor foot screws are loose; ⑩Cage rotor open welding open circuit; winding rotor open circuit; plus stator winding failure.
2. Troubleshooting ①Repair the bearing and replace it if necessary; ②Adjust the air gap to make it even; ③Correct the rotor dynamic balance; ④Straighten the rotating shaft; ⑤Correct the overlapping iron core, ⑥Recalibrate to make it comply with the regulations; ⑦Repair the fan, correct Balance, correct its geometry; ⑧ reinforce; ⑨ tighten the anchor screws; ⑩ repair the rotor winding; repair the stator winding.
Ten, bearing overheating
1. Causes of failure ① Too much grease or too little grease; ② Poor oil quality containing impurities; ③ Improper fit of bearing and journal or end cap (too loose or too tight); ④ Bearing inner hole eccentric, rubbing against shaft; ⑤ Motor The end cover or bearing cover is not installed flat; ⑥ The coupling between the motor and the load is not corrected, or the belt is too tight; ⑦ The bearing gap is too large or too small; ⑧ The motor shaft is bent.
2. Troubleshooting ① Add grease as required (1/3-2/3 of the volume); ② Replace the cleaned grease; ③ If it is too loose, it can be repaired with adhesive, and if it is too tight, it should be turned by a car, and the journal or the inner hole of the end cap should be ground. To make it suitable; ④ repair the bearing cover and eliminate the rubbing points; ⑤ reassemble; ⑥ re-calibrate and adjust the belt tension; ⑦ replace the new bearing; ⑧ correct the motor shaft or replace the rotor.
11. The motor overheats or even smokes
1. Causes of failure ①The power supply voltage is too high, which greatly increases the core heating; ②The power supply voltage is too low, the motor is running with a rated load, and the current is overheated when the winding is heated; ③When the winding is repaired and removed, the thermal disassembly method is improper and burns the core; ④The fixed rotor iron core is rubbed; ⑤The motor is overloaded or frequently started; ⑥The cage rotor has broken bars; ⑦The motor lacks phase and two-phase operation; ⑧Insufficient varnish is set on the winding after rewinding; ⑨High ambient temperature Multiple, or blocked ventilation channels; ⑩ motor fan failure, poor ventilation; stator winding failure (phase, turn-to-turn short circuit; stator winding internal connection error).
2. Troubleshooting ① Reduce the power supply voltage (such as adjusting the tap of the power supply transformer), if the motor Y, Δ connection is wrong, you should correct the connection; ② increase the power supply voltage or replace the thick power supply wire; ③ repair the iron core, eliminate the fault; ④ Eliminate the rubbing points (adjust the air gap or frustration, car rotor); ⑤ reduce the load; control the start according to the specified number of times; ⑥ check and eliminate the rotor winding failure; ⑦ resume three-phase operation; ⑧ adopt the second dipping and vacuum dipping process; ⑨ Clean the motor, improve the ambient temperature, and adopt cooling measures; ⑩ Check and repair the fan, replace it if necessary; repair the stator winding to eliminate the fault.
