1. Fault diagnosis of low-voltage small motor

Specific problem: When the power supply is connected, the motor does not rotate.

Possible problems: 1, power failure: switch failure, blown fuse, disconnected wiring, etc. 2. Winding faults: short circuit between phases, wrong wiring, open circuit, etc. 3. Bearing failure: the stator and rotor get stuck when sweeping holes; 4. The setting value of overcurrent relay is too small; 5. The wiring of the control cabinet is wrong; 6, the motor load is too large or stuck by the drag machinery. Specific problem: the motor is overheated.

Possible problems: 1, power quality: whether the three phases are balanced or not, and whether the voltage fluctuation value is not greater than 10%, otherwise the three-phase unbalanced current will be generated, which will increase the motor loss and lead to the motor heating; 2. Motor overload: Excessive load or motor bore sweeping will cause the three-phase current to exceed the rated value, which will cause the motor to heat up; 3, lack of phase operation, find and solve;

4. Winding fault: turn-to-turn short circuit, etc. 5. The cooling air duct is blocked, and too much dust will also lead to overheating of the motor. Specific problem: stator winding overheating.

Possible problems: 1, motor overload or rotor hole sweeping, or improper selection of motor capacity; 2. The three-phase voltage is unbalanced or lower than the rated value; 3, winding wiring error; 4, the wind is not smooth, and there is too much dust; 5, winding grounding or short circuit.

Specific problem: rotor overheating

Possible problems: 1, broken rotor bar or cracked end ring; 2, the wind road is not smooth; 3, winding welding or turn-to-turn short circuit.

Specific problem: the winding DC resistance is unqualified.

Possible problems: 1, poor welding; 2. The section of the electromagnetic wire is unqualified; 3. The coil size is unqualified;

4, wire length cross-sectional area does not meet the requirements.

Specific problems: motor hole cleaning

Possible problems: 1, bearing failure, rotor sinking; 2, the rotating shaft is bent; 3. The stator and rotor cores are eccentric, oval or partially deformed and protruding; 4. The main engine has impact vibration on the motor; 5. The motor and the main engine are connected by different shafts;

6. Sudden load, electromagnetic vibration of motor and uneven air gap; 7. Inconsistent thermal deformation of iron core; 8. The structural rigidity is not enough, resulting in uneven air gap under the action of magnetic tension.

Specific problem: overheating of rolling bearing.

Possible problems: 1, improper assembly process leads to damage and deformation of raceway surface, resulting in friction and heating during operation; 2、

Bearing and shaft, bearing and bearing chamber are too tight or too loose. In particular, too tight will make the bearing expand when heated, reduce the gap, increase the friction and produce overheating; 3. The machining accuracy of other parts is not enough. For example, different axes at both ends of the frame, different axes of the end cover and the bearing chamber, elliptical machining, etc. will all cause overheating of the bearing. 4. The quality of the bearing itself is poor, the clearance is too large, the raceway is not clean, there is corrosion, and the rolling body is not round; 5. Poor lubrication, too much or too little lubrication and dirty grease.

Specific problems: abnormal noise of bearing: 1, bearing "hissing"

Possible problems: abnormal bearing sound: 1, bearing "hissing" sound and irregular metallic sound irrelevant to speed; 2. The roller makes a crash or "click" sound before driving at low speed; 3. The "rustling" of the rolling sound has nothing to do with the load; 4. The period of scar sound "Gollum" and "Gollum" is directly proportional to the rotation speed; 5. The noise of impurities is very small and irregular, which has nothing to do with the speed, and sometimes it makes a "grunt" sound. Possible problems: 1, too little grease, add grease; 2. This is not a mistake; 3. Add grease; 4. The ball or roller is scratched. If the bearing is overheated, replace it. Bearing inner and outer rings may be damaged, please replace the bearing in time. 5, bearing raceway intrusion impurities, when you hear the sound of "grunt", should clean the bearing, prevent 1, too little grease, add grease; 2. This is not a mistake; 3. Add grease; 4. The ball or roller is scratched. If the bearing is overheated, replace it. Bearing inner and outer rings may be damaged, please replace the bearing in time. 5. Bearing raceway invades impurities. When you hear the "grunt" sound, you should clean the bearing to prevent impurities from entering.

Specific problems: electromagnetic sound 1, poor startup: hair

Possible problems: 1, uneven air gap; 2. The stator may be damaged. Stop the machine to check whether the terminal voltage of the motor is balanced; 3. It is possible that the stator is connected by mistake; 4. The stator and rotor windings are short-circuited or grounded at two points;

5. It is possible that loose core will produce intermediate frequency tooth harmonic sound.

Specific problems: Other abnormal sound couplings or pulleys and

Possible problem: coupling, pulley and shaft are not closely matched.

2. Fault diagnosis of high voltage motor

Specific problem: motor vibration

Possible problem: 1. Appearance inspection: check the installation first. Whether the anchor bolt is loose and touches the ground at three points. Secondly, check whether the three-phase power supply is balanced. If there is any problem, stop it in time and contact relevant departments to solve it.

2, single machine test, visual vibration still exists, should be separated from the coupling, test the motor alone, if the motor does not vibrate, indicating that the vibration is caused by the installation of the main engine or side shaft device. If a single test motor still vibrates, the motor itself is defective. At this time, the instantaneous power failure method can be used to distinguish whether it is electrical or mechanical, or both. Specific problem: electromagnetic noise of motor

Possible problem: cut off the power supply and the noise disappears. First, check and adjust the power supply voltage to make it balanced; cheque

Specific problem: mechanical noise of motor.

Possible problems:: cut off the power supply and the noise will not disappear: 1, check whether the bearing is abnormal; Scream-clean the bearing, change the grease and prevent dust; Hum-adjust the corrugated pad and check the fit and assembly of the bearing cage; Raceway damage-replace bearing 2, vibration and noise caused by rotor imbalance, and balance the rotor; 3. Check the rigidity of the whole machine, improve the rigidity, adjust the fastening parts, improve the vibration and * * *, reinforce the pipeline and reduce the ventilation noise. Specific problems: the matching accuracy of sliding bearings.

Possible problems: the design value of radial clearance between sliding bearing and shaft diameter is generally 0.8~ 1.9 of the nominal size of shaft diameter? In general, the axial clearance between the bearing and the shaft shoulder is 2% of the nominal size of the shaft diameter (unilateral). Specific problem: oil leakage of sliding bearing

Possible problems: This kind of fault mostly occurs in the forced lubrication sliding bearing device. One reason is that the oil pressure is too high, and the fault can be eliminated by adjusting the oil pressure and flow. Another reason is that the internal fan forms negative pressure to absorb oil in the internal area of the bearing, so that it can be checked whether the balance hole and the balance pipeline are unblocked and whether the floating oil seal is intact.

3. Fault diagnosis of high-voltage large motor

Specific problem: motor vibration

Possible problem: 1. Appearance inspection: check the installation first. Whether the anchor bolt is loose and touches the ground at three points. Secondly, check whether the three-phase power supply is balanced. If there is any problem, stop it in time and contact relevant departments to solve it.

2, single machine test, visual vibration still exists, should be separated from the coupling, test the motor alone, if the motor does not vibrate, indicating that the vibration is caused by the installation of the main engine or side shaft device. If a single test motor still vibrates, the motor itself is defective. At this time, the instantaneous power failure method can be used to distinguish whether it is electrical or mechanical, or a mixture of the two. At the moment of power failure, the vibration of the motor immediately disappears or becomes lighter, indicating that the electrical reason is the main reason, otherwise it is likely to be mechanical; 3. Electrical cause inspection: firstly, test whether the stator three-phase winding is balanced and whether there is open welding; Whether the stator is grounded, turn-to-turn short circuit; Whether the rotor has broken cage defects. 4, mechanical reason inspection: mechanical vibration and noise first check whether the air gap between stator and rotor is uniform; Clean the bearing and check the clearance; Check the deformation and loose fit of iron core. If necessary, check the rotor core and do a dynamic balance test; 5. Inspection of the joint: If there is no problem in the above inspection, it means that the vibration of the motor is caused by the joint, so check the horizontal inclination and strength of the foundation; Check the coaxiality with the host installation; Check whether the coupling itself is balanced and whether the connection gap is even and correct. Generally, the lower clearance of the coupling is required to be greater than the upper clearance. Specific problem: electromagnetic noise of motor

Possible problem: cut off the power supply and the noise disappears. First, check and adjust the power supply voltage to make it balanced; cheque

Specific problem: mechanical noise of motor.

Possible problem: cut off the power supply and the noise will not disappear: 1. Check whether the bearing is abnormal; Scream-clean the bearing, change the grease and prevent dust; Hum-adjust the corrugated pad and check the fit and assembly of the bearing cage; Raceway damage-replace bearing. 2, vibration and noise caused by rotor imbalance, balance the rotor; 3, the rotor and shaft loose or loose heat, causing heavy "knock" sound, the frequency is the same as the speed. Replace the rotating shaft with dimension; 4. Check the rigidity of the whole machine, improve the rigidity, adjust the fastening parts, improve the vibration and * * *, reinforce the pipeline and reduce the ventilation noise.

Specific problems: the matching accuracy of sliding bearings.

Possible problems: the design value of radial clearance between sliding bearing and shaft diameter is generally 0.8~ 1.9 of the nominal size of shaft diameter? In general, the axial clearance between the bearing and the shaft shoulder is 2% of the nominal size of the shaft diameter (unilateral). Specific problem: oil leakage of sliding bearing

Possible problems: This kind of fault mostly occurs in the forced lubrication sliding bearing device. One reason is that the oil pressure is too high, and the fault can be eliminated by adjusting the oil pressure and flow. Another reason is that the internal fan forms negative pressure to absorb oil in the internal area of the bearing, so that it can be checked whether the balance hole and the balance pipeline are unblocked and whether the floating oil seal is intact.

4. Mechanical failure of motor

Specific problem: motor vibration

Possible problems: a. rotor imbalance; B. the fan is unbalanced; C. shaft bending; D. the strength and rigidity of the casing are poor; E. uneven air gap; F. deformation and looseness of iron core; G. bearing wear and clearance out of tolerance; H. Open circuit, short circuit and grounding of stator winding; First, the foundation strength and stiffness are insufficient; J. poor coupling assembly; K. the gear adapter is loose; L. the anchor bolt is loose.

Specific problem: bearing overheating

Possible problems: a. Too much or too little grease; B. oil pollution with impurities; C. The inner and outer rings of the bearing are too tightly matched; E. the oil seal is too tight; F, bearing inner and outer cover coaxiality tolerance; G. failure of the bearing itself; H. the coaxiality of butt joint is out of tolerance; 1. Improper bearing selection; J bearing wear and clearance out of tolerance; K. The oil slinger of sliding bearing does not rotate flexibly and the oil supply is not smooth.

Specific problems: analysis of common mechanical failures.

Possible problems: a. Poor bearing quality; B. poor bearing assembly quality; C the shape and position tolerances of the bearing chamber, inner and outer covers, oil slinger, winding ring and other parts are out of tolerance; D. temperature alarm failure; E. there is a problem with installation and maintenance.

Specific problem: rotor runout

Possible problems: a. Electromagnetic force, diamond-shaped iron core of stator and rotor, misalignment of assembly position of stator and rotor; B. asymmetric internal air path; C. The axial clearance of the bearing exceeds the standard; D. Process control error of axial dimension chain of parts; E. poor coupling assembly; F. change the process parameters of the tractor.