Have you checked the three major causes of motor vibration?- YUYAO NINGQI ELECTRIC APPLIANCE CO.,LTD.

The vibration of the motor will shorten the winding insulation and bearing life, and affect the normal lubrication of the sliding bearing. The vibration force promotes the expansion of the insulation gap, causing external dust and moisture to invade it, resulting in a decrease in insulation resistance and an increase in leakage current, and even an insulation breakdown Wait for the accident.
In addition, the vibration of the motor will easily cause the water pipe of the cooler to vibrate and the welding point will vibrate. At the same time, it will cause damage to the load machinery, reduce the accuracy of the workpiece, cause fatigue of all mechanical parts subject to vibration, and loosen the anchor screws. Or cut off.
The vibration of the motor will cause abnormal wear of the carbon brushes and slip rings, and even severe brush fire will burn the collector ring insulation, and the motor will produce a lot of noise. This situation generally occurs in DC motors.
There are three main reasons for vibration:

Electromagnetic reasons; mechanical reasons; electromechanical hybrid reasons.

1. Electromagnetic reasons

1. In terms of power supply: three-phase voltage is unbalanced, and the three-phase motor runs under phase loss.

2. On the stator: the stator core becomes elliptical, eccentric, and loose; the stator winding has broken wire, ground breakdown, inter-turn short circuit, wiring error, and the stator three-phase current is unbalanced.

Typical Case:

Red powder was found in the stator core before the boiler room sealing fan motor was overhauled. It is suspected that the stator core is loose, but it is not within the scope of the standard overhaul, so it has not been processed. The motor made a piercing squeal during the test run after the overhaul. Replace it. Troubleshooting after the stator is installed.

3. Rotor failure: the rotor core becomes elliptical, eccentric or loose. The rotor cage bar and the end ring are open welding, the rotor cage bar is broken, the winding is wrong, the brush contact is poor, etc.

Typical Case:

During the operation of the toothless saw motor in the sleeper section, the stator current of the motor was found to swing back and forth, and the motor vibration gradually increased. According to the phenomenon, it was judged that the motor rotor cage bar might be welded and broken. After the motor was disassembled, it was found that the rotor cage bar was broken in 7 places, which was serious. The two sides and the end ring have all broken. If it is not found in time, it may cause a bad accident of stator burning.

2. Mechanical reasons

1. The motor itself

Unbalanced rotor, bent shaft, deformed slip ring, uneven air gap between stator and rotor, inconsistent magnetic center of stator and rotor, bearing failure, poor foundation installation, insufficient mechanical strength, resonance, loose anchor screws, motor fan damage.

Typical Case:

After replacing the upper bearing of the condensate pump motor in the factory, the shaking of the motor increased, and there were slight signs of sweeping in the rotating and stator. After careful inspection, it was found that the motor rotor was not raised at the correct height and the magnetic center of the rotating and stator was not aligned. Re-adjust the thrust head screw After the cap is prepared, the motor vibration fault is eliminated.

The vibration of the cross-line hoisting ring hoisting motor has been large after overhaul, and there are signs of gradual increase. When the motor is off the hook, it is found that the vibration of the motor is still large, and there is a large string movement in the axial direction. It is found that the rotor core is loose after disassembly. , The balance of the rotor is also problematic. After replacing the spare rotor, the fault is eliminated, and the original rotor is returned to the factory for repair.

2. In terms of coordination with the coupling

The coupling is damaged, the coupling is poorly connected, the coupling is not centered correctly, the load is unbalanced, and the system is resonant. The shaft system of the linkage part is misaligned, the center line does not coincide, and the centering is incorrect. This kind of failure is mainly caused by poor alignment and improper installation during the installation process.

There is another situation, that is, the center lines of some linkage parts coincide in the cold state, but after a period of operation, due to the deformation of the rotor fulcrum and foundation, the center line is destroyed again, and vibration occurs.

Typical Case:

a. Circulating water pump motor, the vibration has been too large during operation, the motor inspection has no problems, and everything is normal without load. The water pump team thinks that the motor is running normally, and finally checked that the motor alignment center difference is too large. After the pump team recalibrates , The motor vibration is eliminated.

b. After replacing the pulley in the boiler room induced draft fan, the motor vibrates during trial operation and the three-phase current of the motor increases. Check all circuits and electrical components without problems. Finally, the pulley is found to be unqualified. After the replacement, the vibration of the motor is eliminated, and the three-phase motor is at the same time The current also returned to normal.

3. Reasons for motor mixing

1. Motor vibration is often caused by uneven air gap, which causes unilateral electromagnetic tension, and unilateral electromagnetic tension further increases the air gap. This electromechanical hybrid effect is manifested as motor vibration.

2. The motor axially moves in series. The electromagnetic tension caused by the rotor's own gravity or installation level and the magnetic center is not correct, which causes the motor to move in the axial direction, causing the motor to vibrate. In severe cases, the shaft wears roots and causes the bearing temperature Rise rapidly. The gears and couplings connected to the motor are faulty. This kind of failure is mainly manifested as poor gear engagement, serious gear tooth wear, poor lubrication of the wheel, coupling skew, misalignment, gear coupling tooth profile, incorrect tooth pitch, excessive clearance or serious wear, which will cause certain problems. vibration.

Defects in the structure of the motor itself and installation problems. This kind of failure is mainly manifested as the ellipse of the shaft journal, the bending of the rotating shaft, the excessive or small gap between the shaft and the bearing bush, the insufficient rigidity of the bearing seat, the foundation plate, the foundation and the entire motor installation foundation, and the motor and the foundation plate are fixed. Insufficient, loose foot bolts, looseness between the bearing seat and the base plate, etc. The gap between the shaft and the bearing bush is too large or too small can not only cause vibration, but also cause abnormal lubrication and temperature of the bearing bush.

3. The load driven by the motor conducts vibration

Typical Case:

The vibration of the steam turbine of the steam turbine generator and the vibration of the fan and water pump driven by the motor cause the motor to vibrate.