Causes of motor vibration
1. Vibration caused by electromagnetic factors
● Power supply: Three-phase voltage is unbalanced, and the three-phase motor is operating with a single phase.
●Stator-related issues: Stator core becomes elliptical, eccentric, or loose; stator windings experience open circuits, grounding breakdowns, inter-turn short circuits, wiring errors, and unbalanced three-phase stator currents.
●Rotor faults: Elliptical rotor core, eccentricity, loosening, weld failure between rotor cage bars and end rings, broken rotor cage bars, incorrect winding, poor brush contact, etc.
2. Vibration caused by a combination of factors in the motor.
● Motor vibration is often caused by uneven air gap, which leads to unilateral electromagnetic pull. This unilateral electromagnetic pull further increases the air gap. This electromechanical hybrid effect manifests as motor vibration.
●Axial movement of the motor is caused by electromagnetic pull due to the rotor's own weight, improper installation level, or misalignment of the magnetic center. This leads to increased motor vibration and, in severe cases, shaft wear at the bearing root, causing the bearing temperature to rise rapidly.
3. Vibration caused by mechanical reasons
●Motor itself: rotor imbalance, bent shaft, deformed slip ring, uneven air gap between stator and rotor, inconsistent magnetic centers between stator and rotor, bearing failure, poor foundation installation, insufficient strength of mechanical mechanism, resonance, loose foundation bolts, damaged motor fan.
●Coupling Fit: Problems include damaged couplings, poor coupling connection, inaccurate coupling alignment, unbalanced load machinery, and system resonance. Misalignment of the shafts in the linkage components, misalignment of center lines, and incorrect centering are common causes of this fault. These problems are primarily due to improper alignment or installation during the process. Another possibility is that the center lines of some linkage components may coincide when cold, but after a period of operation, deformation of the rotor support, foundation, etc., can disrupt the center lines, leading to vibration.
Methods for handling motor vibration problems
1. Troubleshooting electrical issues
First, check if the three-phase DC resistance of the stator is balanced. If it is unbalanced, it indicates that there is a weld break at the stator connection welding point. Disconnect the winding phases to check. Also, check if there is a short circuit between turns in the winding. If the fault is obvious, you can see burn marks on the insulation surface, or use an instrument to measure the stator winding. After confirming the short circuit between turns, rewire the motor winding.
2. Inspection of the load-bearing mechanical parts
Check the motor's foundation level, tilt, strength, whether the center alignment is correct, whether the coupling is damaged, and whether the motor shaft extension deflection meets the requirements.
3. Troubleshooting mechanical issues:
Check if the air gap is uniform. If the measured value exceeds the standard, readjust the air gap. Check the core for deformation and looseness. Loose cores can be glued and filled with epoxy resin. Check the shaft. Repair bent shafts or replace them with new ones. Then perform a balance test on the rotor. Check the bearings and measure the bearing clearance. If there are journal defects, restore the original dimensions and reassemble the bearings.
Using Banner's QM42VT sensor to prevent motor vibration risks
▲Banner Wireless Vibration and Temperature Monitoring Solution
Improving preventative maintenance helps users plan equipment maintenance and spare parts availability, thereby minimizing the risk of production line downtime.
▲Equipment operating status curve diagram
The QM42VT is responsible for collecting vibration and temperature signals from the motor and transmitting them wirelessly to a remote system.
▲On-site equipment data collection
Banner's DataWatch software allows for customization of the software interface to meet customer needs. Historical curve playback functionality is also available.
▲Equipment status monitoring interface
