Three-phase asynchronous motorIt is widely used in general occasions without flammable, explosive or corrosive gas and mechanical equipment without special requirements, such as metal cutting machine tools, pumps, fans, transportation machinery, mixers, agricultural machinery and food machinery.

　　ThisThree-phase asynchronous motorWhen there is a problem in the operation, four methods can be used to prevent and remove the problem in time by watching, listening, smelling, and touching, so as to ensure the safe operation of the motor. 　　one look

　　ObservedThree-phase asynchronous motorWhether there are abnormalities in the operation process, the main manifestations are as follows.

　　1. When the stator winding is short-circuited, you will see smoke from the motor.

　　2. If there are discoloration, burn marks and smoke trails at the touch points and connections in the motor, it means that there is some overheating, poor touch at the conductor connections, or burned windings, etc.

　　3. If the motor oscillates violently, the transmission device is stuck, the motor is not fixed well, the foot bolts are loose, etc.

　　4. When the electricity is seriously overloaded or the phase is missing, the speed will slow down and there will be a heavier "hum" sound.

　　5. When the motor is operating normally, but suddenly stopped, you will see sparks from the loose wiring; the fuse is blown or a part is stuck.

　　Second, listen

　　Three-phase asynchronous motorDuring normal operation, an even and lighter "humming" sound should be declared, without noise and special noise.If it is declared that the noise is too large, electromagnetic noise, bearing noise, ventilation noise, mechanical conflict sound, etc., are all precursors or symptoms of faults.

　　1. Regarding electromagnetic noise, the motor announces the high and low and heavy sound, the reasons are as follows.

　　(1) The air gap between the stator and the rotor is uneven, the noise fluctuates high and low, and the interval between high and low sounds does not change. This is caused by the wear of the bearing, which makes the stator and the rotor not concentric.

　　(2) The iron core is loose.When the motor oscillates during operation, the fixing bolts of the iron core are loosened and the silicon steel sheet of the iron core becomes loose, and noise is announced.

　　(3) The three-phase current of the motor is unbalanced.This is because the three-phase windings are grounded incorrectly, short-circuited, or poorly touched. If the sound is very annoying, it means that the motor is seriously overloaded or phase-loss operation.

　　2. If the transmission organization and the transmission organization announce that the sound is continuous instead of fluctuating up and down, it can be divided into the following types.

　　(1) The periodic "crack" sound is caused by the belt joints not being slippery.

　　(2) Periodic "boom boom" sound is caused by the loosening between the coupling or the pulley and the shaft and the wear of the key or keyway.

　　(3) The uneven knocking sound is caused by the wind blade knocking against the fan cover.

　　3. Regarding bearing noise, you should always monitor the motor during operation.The monitoring method is: press one end of the screwdriver against the bearing device part and the other end close to the ear to hear the sound of bearing operation.If the bearing is operating normally, the sound will be successive and subtle \"sanding\" sounds, and there will be no high and low changes and metal clashes.If the following sounds appear, it is abnormal.

　　(1) There is a "squeak" sound when the bearing is operating. This is the sound of metal conflict, which is caused by the lack of oil in the bearing. The bearing should be disassembled and added with an appropriate amount of grease.

　　(2) If there is a "chill" sound, which is the sound announced when the ball is rotating, it is caused by the dryness of the grease or the lack of oil, and an appropriate amount of grease can be added.

　　(3) If there is a "click" or "creak" sound, it is the sound produced by the irregular movement of the balls in the bearing, which is caused by the damage of the balls in the bearing or the lack of the motor for a long time, and the grease is dry. of.

　　Three, touch

　　touchThree-phase asynchronous motorThe temperature of the part can also determine the cause of the problem.To ensure safety, use the back of your hand to touch the motor housing and the surrounding parts of the bearing when touching with your hands. If the temperature is abnormal, the reasons are as follows.

　　1. Poor ventilation.Such as the electric fan falls off, the ventilation duct is blocked, etc.

　　2. Overload.The current is too large and the stator windings are overheated.

　　3. Short circuit between stator winding turns or unbalanced three-phase current.

　　4. Frequent starting or braking.

　　5. If the temperature around the bearing is too high, it is caused by damage to the bearing or lack of oil.

　　Four, smell

　　After smelling the smell of the electric motor, it can be judged and prevented.If there is a special paint smell, it indicates that the internal temperature of the motor is too high; if there is a heavy paste smell or burnt smell, the insulation layer has been broken down or the winding has been burned.

　　Analysis and removal of motor faults

　　Three-phase asynchronous motorIt is widely used, but after a long period of operation, various faults will occur, and timely identification of the cause of the fault and corresponding actions are an important operation to avoid the expansion of the fault and ensure the normal operation of the equipment.

　　XNUMX. The motor does not turn and has a buzzing sound after power-on

　　l.Causes of the fault ①The stator and rotor windings are open (one-phase disconnection) or one phase of the power supply is lost; ②the winding lead wires are connected wrongly at the beginning and the end or the internal windings are connected reversely; ③the power circuit contacts are loose and the touch resistance is large; ④the motor is overloaded Large or the rotor is stuck; ⑤The power supply voltage is too low; ⑥The small motor assembly is too tight or the grease in the bearing is too hard; ⑦The bearing is stuck.

　　2.Removal of faults ①Identify the breakpoint and correct it; ②Check the winding polarity; determine whether the end of the winding is correct; ③Tighten loose wiring screws, use a multimeter to determine whether each connector is falsely connected, and correct it; ④Reduce or detect and eliminate For mechanical faults, ⑤ check that the regular surface connection method is incorrectly connected to Y; whether the power wire is too thin and the voltage drop is too large, correct it, ⑥ re-assemble it to make it sensitive; replace qualified grease; ⑦ correct the bearing.

　　XNUMX. The motor does not rotate after power-on, and then the fuse is blown

　　1.The cause of the fault ① lack of one-phase power supply, or the fixed and dry coils are connected oppositely; ② the stator winding is short-circuited between the phases; ③ the stator winding is grounded; ④ the stator winding is connected incorrectly;

　　2.Fault removal ①Check whether one phase of the knife switch is not closed, but one phase of the power circuit is disconnected; eliminate the reverse connection problem; ②detect the short-circuit point and correct it; ③eliminate the grounding; ④detect the misconnection and correct it; ⑤replace Fuse; ③ Eliminate the grounding point.

　　XNUMX. The motor can't rotate after power on, but there is no abnormal noise, no strange smell and smoke.

　　1.The cause of the fault: ①The power supply is not connected (at least two phases are not connected); ②The fuse is blown (at least two phases are blown); ③The overcurrent relay is adjusted too small; ④The control device is connected incorrectly.

　　2.Fault removal: ①Check the power circuit switch, whether there are breakpoints at the fuse and junction box, and correct it; ②Check the type of fuse, the cause of the fuse, and replace it with a new one; ③Adjust the relay setting value to cooperate with the motor; ④Correct the wiring.

　　Fourth, it is difficult to communicate with the motor to start, and the motor speed is much lower than the extra speed when there is an additional load

　　1.The cause of the fault ①The power supply voltage is too low; ②The surface connection motor is wrongly connected to Y; ③The cage rotor is open or broken; ④The stator and rotor part of the coil is connected or reversed; ③Too many turns when correcting the motor winding; ⑤The motor is overloaded .

　　2.Fault removal ①Measure the power supply voltage and try to improve; ②Correct the connection method; ③Check the open welding and breakpoints and correct them; ④Identify the wrong connection and correct it; ⑤Recover the correct number of turns; ⑥Reduce the load.

　　XNUMX. The noise of the motor is abnormal and abnormal noise during operation

　　1.Causes of faults ①The rotor rubs against the stator insulation paper or slot wedge; ②The bearing is worn or there are foreign objects such as sand particles in the oil; ③The stator and rotor cores are loose; ④The bearing is out of oil; The iron cores are rubbed together; ⑦The power supply voltage is too high or unbalanced; ⑧The stator winding is connected or short-circuited.

　　2.Fault removal ① Trim insulation and cut low groove wedges; ② Replace bearings or clean bearings; ③ Repair stator and rotor cores; ④ Refuel; ⑤ Clean the air duct; reinstall the device; ⑥ Eliminate scratches, if necessary, the small rotor in the car; ⑦Check and power supply voltage; ⑧Eliminate stator winding faults.

　　Six, Y seriesThree-phase asynchronous motorThe no-load current is unbalanced, and the three-phase difference is large

　　1.Causes of the problem ①When rewinding, the number of turns of the three-phase winding of the stator is not equal; ②The winding ends are connected wrongly; ③The power supply voltage is unbalanced; ④The winding has problems such as short circuit between turns and reverse connection of coils.

　　2.Removal of faults ① Wind the sub-winding from the beginning; ② Check and correct; ③ Measure the power supply voltage and try to eliminate the imbalance; ④ Remove the winding faults.

　　Seven, the motor no-load current is balanced, but the value is large

　　1.The cause of the fault ①The number of turns of the stator winding was reduced too much during the correction; ②The power supply voltage was too high; ③The Y-connected motor was incorrectly connected as Δ; ④The rotor was installed in reverse during the motor assembly, which made the stator core not aligned and the effective length was shortened; ⑤ The air gap is too large or uneven; ⑥The hot disassembly method is improper when the old winding is removed for overhaul, which will cause the iron core to burn.

　　2.Fault removal ①Rewind the stator winding to recover the correct number of turns; ②Try to recover the extra voltage; ③Change to Y; ④Re-assemble; ③Replace the new rotor or air gap; ⑤Repair the iron core or calculate the winding from the beginning, and the appropriate number of turns.

　　Eight, the bearing is overheated

　　1.Causes of fault ① Too much or too little grease; ② Poor oil quality and impurities; ③ Improper cooperation between the bearing and the journal or end cover (too loose or too tight); ④ The inner bore of the bearing is eccentric and rubs against the shaft; ⑤ The motor end cover or bearing cover is not installed flat; ⑥The coupling between the motor and the load is not calibrated, or the belt is too tight; ⑦The bearing gap is too large or too small; ⑧The motor shaft is bent.

　　2.Removal of faults ①Add grease according to the rules (1/3-2/3 of the volume); ②Replace clean grease; ③Correction of too loose binder, over-tightening of the car, grinding the axle neck or the inner hole of the end cover, Make it suitable; ④repair the bearing cover to eliminate rubbing points; ⑤assemble from the beginning; ⑥recalibrate, belt tension; ⑦replace the new bearing; ⑧check the motor shaft or replace the rotor.

　　XNUMX. When the motor is unloaded or overloaded, the ammeter pointer is unstable and swings

　　1.Causes of the fault ①The cage-type rotor guide bar is open or broken; ②The winding-type rotor is faulty (one-phase open circuit) or the short-circuit device of the brush and collector ring is not touched.

　　2.Removal of faults ①If the broken bar is detected, correct or replace the rotor; ②Check and correct the circuit around the rotor.

　　XNUMX. The motor oscillates during operation

　　1.Causes of fault ①Abrasion bearing clearance is too large; ②Uneven air gap; ③Unbalanced rotor; ④Rotating shaft tortuous; ⑤Iron core deformation or looseness; ⑥Uncorrected coupling (pulley) center; ⑦Unbalanced electric fan; ⑧Chassis Or the basic strength is not enough; ⑨The motor foot screw is loose; ⑩Cage rotor is open and welded; the winding rotor is open; and the stator winding is faulty.

　　2.Fault removal ①Check the bearing and replace it if necessary; ②The air gap, make it even; ③Check the rotor dynamic balance; ④Straighten the shaft; ⑤Check the stacked iron core, ⑥Check from the beginning to make it comply with the rules; ⑦Check the electric fan, check the balance , Correct its geometric shape; ⑧ strengthen; ⑨ tighten the anchor screws; ⑩ modify the rotor winding; modify the stator winding.

　　XNUMX. The motor overheats and even smokes

　　1.The cause of the fault ①The power supply voltage is too high, which causes the iron core to heat up greatly; ②The power supply voltage is too low, and the motor is operated with additional load, and the current is too high to cause the winding to heat up; ③When repairing and removing the winding, the hot disassembly method is inappropriate, and the iron core is burned; ④The stator and rotor cores are rubbed together; ⑤The motor is overloaded or frequently started; ⑥The cage-type rotor is broken; ⑦The motor lacks phase, two-phase operation; ⑧After rewinding, the winding paint is not sufficient; ⑨The surface of the motor is dirty with high ambient temperature Or the ventilation duct is blocked; ⑩motor fan fault, poor ventilation; stator winding fault (phase-to-phase, inter-turn short circuit; stator winding internal connection fault).

　　2.Fault removal ①Reduce the power supply voltage (such as the tap of the power supply transformer), if it is caused by the wrong connection of the motor Y and Δ, the connection should be corrected; ②Increase the power supply voltage or change the thick power supply wire; ③Repair the iron core and remove the fault; ④Remove Wipe points (air gap or frustration, car rotor); ⑤ load reduction; control the start according to the regular number of times; ⑥ check and eliminate rotor winding faults; ⑦ rehabilitation three-phase operation; ⑧ use secondary dipping and vacuum dipping process; ⑨ cleaning For the electric motor, improve the ambient temperature and choose cooling methods; ⑩ check and correct the electric fan, and replace it if necessary; check and repair the stator winding to eliminate defects.