Analysis of common faults of three-phase asynchronous motor. Do you want to know? Slip-ring motor brushless and loop-free hydraulic resistance starter, magnetically controlled (magnetically saturated) soft starter, high-low voltage motor hydraulic resistance starter and hydraulic resistance governor Editor: motor soft start net-motor soft start net Release time: 2008-6-2 1 Reading times: 772 1 There are many kinds of three-phase asynchronous motors with three-phase asynchronous motor structures, but there are various three-phase asynchronous motors. In addition, there are end caps, bearings, junction boxes, rings and other accessories. The stator of a three-phase motor generally consists of a shell, a stator core and a stator winding (which can be connected into a star Y shape or a triangle triangle). The rotor is mainly composed of rotor core and rotor winding (which can be divided into wound rotor asynchronous motor and cage asynchronous motor), and other parts include end cover, fan and so on. 2. Analysis of common faults 2. 1. The motor can't rotate after being electrified, but there is no abnormal sound, odor and smoke. 2. 1. 1 Cause of failure: ① Power failure (at least two-phase failure); (2) Fuses are blown (at least two phases are blown); ③ The overcurrent relay is too small; (4) The wiring of the control equipment is wrong; Wait a minute. 2. 1.2 Troubleshooting: ① Check whether there are breakpoints in the switches, fuses and junction boxes of the power supply circuit and repair them; (2) Check the fuse model and fuse reason, and replace it with a new fuse; ③ Adjust relay setting value to cooperate with motor; ④ Correct the wiring. 2.2, the motor does not turn after power-on, and then the fuse blows. 2.2. 1 Cause of failure: ① One-phase power supply is missing, or one stator coil is connected reversely; ② Short circuit between stator windings; ③ Stator winding grounding; (4) Wrong connection of stator winding; ⑤ The fuse section is too small; Wait a minute. 2.2.2 Troubleshooting: ① Check whether one phase circuit breaker is not closed or the power supply circuit is disconnected; Eliminate the reverse connection fault; (2) Find out the short circuit point and repair it; ③ Eliminate grounding; (4) Find out the wrong connection and correct it; ⑤ Replace the fuse; 2.3. There is no hum of the motor after electrifying. 2.3. 1 Cause of failure: ① Stator and rotor windings are open (one phase is open) or power supply is cut off in one phase; (2) The lead-out wires of the winding are wrongly connected at the beginning and the end, or the winding is internally connected reversely; (3) The contact of power supply circuit is loose, and the contact resistance increases; (4) The motor is overloaded or the rotor is stuck; ⑤ The power supply voltage is too low; ⑥ The small motor is assembled too tightly or there is too much grease in the bearing; ⑦ The bearing is stuck; Wait a minute. 2.3.2 Troubleshooting: ① Find the breakpoint and repair it; ② Check winding polarity; Jud whether that end of win is correct; (3) Tighten the loose wiring screws, judge whether each joint is false with a multimeter and repair it; (4) Load rejection or finding out and eliminating mechanical failure; (5) Check whether the specified delta is connected to y by mistake; Whether the voltage drop is too large due to the thin power conductor, correct it, 6 reassemble it to make it flexible; Replace qualified grease; ⑦ Repair the bearing. 2.4. The motor is difficult to start, and the motor speed is lower than the rated speed when the load is rated. 2.4. 1 reason: ① the power supply voltage is too low; ② △ Motor misconnection is y; ③ Cage rotor is welded or broken; ④ The local coils of stator and rotor are connected by mistake or reverse; ③ Too many turns are added when repairing the motor winding; ⑤ Motor overload; Wait a minute. 2.4.2 Troubleshooting: ① Measure the power supply voltage and try to improve it; ② Correct connection; (3) Check welding and breakpoints and repair them; (4) Find out the mistakes and correct them; ⑤ Restore the correct number of laps; ⑥ Reduce the load. 2.5. The no-load current of the motor is unbalanced, and the three-phase difference is 3. 5. 1. Reason: ① When rewinding, the number of turns of stator three-phase winding is not equal; (2) The winding ends are wrongly connected; ③ unbalanced power supply voltage; ④ Faults such as turn-to-turn short circuit and coil reverse connection exist in the winding; Wait a minute. 3.5.2 Troubleshooting: ① Rewinding the stator winding; ② Check and correct; (3) measure the power supply voltage, try to eliminate the imbalance; (4) suddenly eliminate the winding fault. 2.6. When the motor is unloaded and overloaded, the ammeter pointer is unstable and swings. 3.6. 1 Cause of failure: ① The cage rotor bar is welded or broken; ② Winding rotor fault (one-phase open circuit) or poor contact between brush and collector ring short circuit device; Wait a minute. 3.6.2 Troubleshooting: ① Find out the broken bars and repair or replace the rotor; ② Check the circuit around the rotor and repair it. 2.7. The no-load current of the motor is balanced, but the value is 3.7. 1. Cause of failure: ① The number of turns of stator winding is reduced too much during repair; ② The power supply voltage is too high; ③Y-connected motor is mistakenly connected with δ; (4) When the motor is assembled, the rotor is installed backwards, so that the stator core is dislocated and the effective length is shortened; ⑤ The air gap is too large or uneven; ⑥ When the old winding is dismantled in overhaul, the iron core is burnt out due to improper hot dismantling method; Wait a minute. 2.7.2 Troubleshooting: ① Rewind the stator winding to restore the correct number of turns; ② Try to restore the rated voltage; Change 3 to y; ④ reassembly; ③ Replace the rotor with a new one or adjust the air gap; ⑤ Repair the iron core or recalculate the winding, and appropriately increase the number of turns. 2.8. There is abnormal noise when the motor is running. 3.8. 1 Cause: ① Rotor rubs against stator insulation paper or slot wedge; (2) Bearing wear or sand and other foreign bodies in oil; ③ The stator and rotor cores are loose; ④ The bearing is short of oil; ⑤ Air duct stuffing or fan cover wiping, ⑤ stator and rotor iron cores rubbing against each other; ⑦ The power supply voltage is too high or unbalanced; ⑧ Wrong or short-circuited stator winding; Wait a minute. 3.8.2 Troubleshooting: ① Repair insulation and reduce slot wedge; ② Replace the bearing or clean the bearing; ③ Overhaul the stator and rotor cores; 4 come on; ⑤ Clean the air duct; Reinstall; 6. Eliminate scratches, and if necessary, install the small rotor on the car; ⑦ Check and adjust the power supply voltage; ⑧ Troubleshooting the stator winding. 2.9. The motor vibrates greatly during operation. 3.9. 1 Cause of failure: ① bearing clearance is too large due to wear; ② uneven air gap; ③ rotor imbalance; (4) the rotating shaft is bent; (5) Deformation or looseness of iron core; ⑥ The center of coupling (pulley) is not corrected; ⑦ The fan is unbalanced; End casing or foundation strength is not enough; Pet-name ruby motor anchor screw loose; Attending open welding circuit of cage rotor; Open circuit of winding rotor; Increase stator winding fault; Wait a minute. 3.9.2 Troubleshooting: ① Repair the bearing and replace it if necessary; ② Adjust the air gap to make it uniform; ③ Correcting rotor dynamic balance; ④ Straighten the rotating shaft; ⑤ Correct overlapping iron cores, ⑤ Re-correct them to make them conform to regulations; ⑦ Repair the fan, correct the balance and its geometry; 8 reinforcement; Pet-name ruby fastening anchor screw. 2. 10, bearing overheating 3. 10. 1 Cause of failure: ① Too much or too little grease; ② The oil quality is not good and contains impurities; ③ Improper cooperation between bearing and journal or end cover (too loose or too tight); (4) eccentric bearing hole, friction with the shaft; ⑤ The motor end cover or bearing cover is installed unevenly; ⑥ The coupling between motor and load is not corrected, or the belt is too tight; ⑦ bearing clearance is too large or too small; 8 motor shaft bending; Wait a minute. 2. 10.2 Troubleshooting: ① Add grease (1/3-2/3 by volume) as required; ② Replace clean grease; (3) Too loose can be repaired with glue, too tight should be turned, and the inner hole of the journal or end cover should be polished to make it match; (4) Repair the bearing cover and eliminate friction points; (5) reassembly; ⑥ Recalibrate and adjust the belt tension; ⑦ Replace new bearings; Finally correct the motor shaft or replace the rotor. 2. 1 1, motor overheating or even smoking 2.1.1Cause of failure: ① The power supply voltage is too high, which greatly increases the core heating; (2) The power supply voltage is too low, the motor runs with rated load, and the current is too large to heat the winding; (3) When repairing and disassembling the winding, improper thermal disassembly method is adopted to burn out the iron core; (4) The stator and rotor iron core rub together; ⑤ Motor is overloaded or frequently started; ⑥ Broken bars of cage rotor; ⑦ The motor lacks phase and operates in two phases; ⑧ After rewinding, the winding is not completely dipped in paint; Pet-name ruby high ambient temperature motor surface dirty, or ventilation is blocked; Wait a minute. 2. 1 1.2 Troubleshooting: ① Reduce the power supply voltage (such as adjusting the tap of the power transformer), and correct the wiring if it is caused by the wrong wiring of motors Y and δ; (2) increase the power supply voltage or replace the thick power cord; (3) iron core maintenance and troubleshooting; (4) Eliminating rubbing points (adjusting air gap or rotating rotor); ⑤ Load rejection; Control startup according to the specified number of times; ⑥ Check and eliminate rotor winding faults; ⑦ Restore three-phase operation; (8) adopting secondary paint dipping and vacuum paint dipping processes; Pet-name ruby cleaning motor, improve the ambient temperature, take cooling measures.