The relatively large axial vibration of the air compressor motor indicates that there must be a problem with the motor shaft. There are several factors that cause this situation: electromagnetic problems, mechanical problems, and electromechanical mixing problems. If it is a newly installed motor shaft on the air compressor. This problem is generally caused by the error in the position of the rotor and stator when the bearing is installed. If this problem occurs in a bearing that has been used for a long time, it is generally caused by the wear reaching a certain value. Normally, a gasket can be added appropriately. If the situation does not improve after adding a gasket, it is recommended to replace the bearing directly.
Today, this article will explain the causes of vibration, inspection methods, and treatment methods, hoping to play a certain role in the front-line maintenance of air compressors.
The cause of vibration
1. Electromagnetic
Power supply: three-phase voltage (unbalanced, three-phase motor run out of phase)
Power supply: three-phase voltage (unbalanced, three-phase motor run out of phase)
In the stator: the iron core becomes elliptical, eccentric, loose, winding disconnection, grounding breakdown, inter-turn short circuit, wrong wiring, unbalanced three-phase current.
Rotor failure: the iron core becomes elliptical, eccentric, and loose, and the rotor short-circuit ring and cage bar are welded and broken. The three-phase winding of the wound rotor is unbalanced, the winding is disconnected, the grounding breakdown, the inter-turn breakdown, the wiring error, and the brush contact is poor.
2. Mechanical aspects
In terms of the motor itself: the rotor is unbalanced, the rotating shaft is bent, the slip ring is deformed, the air gap between the stator and the rotor is uneven, and the magnetic force center is inconsistent. Bearing failure: Poor foundation installation. Mechanical strength is not enough. Resonance, loose anchor screws, damage to the motor fan. When the bearing is running close to its service life, the vibration of the motor gradually increases, and there is noise in the running of the bearing.
Coupling cooperation: the coupling is damaged, the connection is poor, the centering is not allowed to load the mechanical unbalanced system resonance.
3. Reasons for electromechanical mixing
The axial movement of the motor, the electromagnetic tension caused by the gravity of the rotor itself or the installation level and the wrong magnetic force center cause the motor to move axially, causing the motor to vibrate more, and in severe cases, the bearing pad is worn, and the temperature of the bearing pad rises rapidly. Find the cause of the vibration.
Causes and treatment methods of large axial vibration of air compressor motor
Second, the investigation method
1. Before the motor is stopped, use a vibration meter to check the vibration of each part, and test the vibration value in detail according to three aspects of the vertical, horizontal and axial directions for the parts with large vibration.
If the anchor screw or bearing end cover screw is loose, it can be tightened directly, and then measure the vibration to see if it is eliminated or reduced.
Next, check the three-phase power supply: whether the voltage is balanced or not, whether there is phase loss or not. The operation of the motor without phase not only causes vibration but also causes the motor to heat up rapidly. Observe whether the pointer of the power supply meter swings back and forth, and the current swing will occur when the rotor is broken (Public Number: Pump housekeeper), and finally check whether the three-phase current of the motor is balanced, and stop the operation in time if any problem is found to prevent the motor from burning.
2. If the vibration of the motor is still not resolved after the treatment of the surface phenomenon, the power supply must be disconnected to release the coupling. If the motor vibrates in an empty test, it means that there is a problem with the motor itself. In addition, the power-off method can be used to distinguish the electrical cause or the mechanical cause. When the power is cut off, the motor will not vibrate immediately or the vibration will be reduced, indicating that it is an electrical cause, or it is a mechanical failure. Repair the cause of the failure.
3. Maintenance method
1. Maintenance of electrical reasons: First, determine whether the three-phase DC resistance of the stator is balanced. If it is unbalanced, it means that there is an open welding phenomenon in the welding part of the stator connection. Disconnect the winding and separate the phases to find out whether there is a short circuit between turns in the other windings, such as failure. Burn marks can be clearly seen from the insulating surface, or the stator windings can be measured with an instrument. After confirming the short circuit between turns, the electrical windings are taken off the wire again.
2. Maintenance for mechanical reasons: check whether the air gap is uniform, if the measured value exceeds the standard, re-adjust the air gap, check the bearing, if the measured gap is unqualified, replace the bearing, check the deformation and looseness of the iron core, and use epoxy resin glue for the loose iron core. Bonding and filling, checking the rotating shaft, re-welding the curved rotating shaft or directly straightening the shaft, and then performing a balance test on the rotor.
3. The mechanical inspection of the load is normal, and there is no problem with the electrical itself. The fault is caused by the connection part. At this time, it is necessary to check whether the basic level, inclination, strength and center alignment of the motor are correct, the coupling is broken, and the motor Whether the shaft phase tolerance meets the requirements.