why does it vibrate?

      Mainly in the aspects of power supply, stator and rotor faults and the matching of the coupling of the motor itself, we will explain in detail below.

Power supply:three-phase voltage ( unbalanced, three-phase motor running without phase )

Stator aspect:the iron core becomes elliptical, eccentric and loose, winding breaks, grounding breakdown, inter-turn short circuit, wrong wiring and 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 stage of the wound rotor is unbalanced, and the winding is broken, grounded, inter-turn, wrong connection and poor brush contact

Motor itself:rotor imbalance, shaft bending, slip ring deformation, uneven air gap between stator and rotor, and inconsistent magnetic center. Bearing failure:poor foundation installation. The mechanical strength is not enough. Resonance, looseness of anchor screw and damage of motor fan. When the bearing is running close to its service life, the vibration of the motor increases gradually and there is noise in the bearing running, which may lead to shaft lapping and sweeping.

Coupling coordination:coupling damage, poor connection and no resonance of mechanical unbalanced load system.

The vibration of the motor is often uneven in air gap, which causes unilateral electromagnetic pulling force, and the pulling force further increases the air gap, and the electromechanical mixing effect is manifested as electromechanical vibration.

The motor runs in series in the axial direction, the gravity of the rotor itself or the installation level and the electromagnetic tension caused by the incorrect magnetic center cause the motor to run in series in the axial direction, causing the motor to vibrate more, seriously causing the bearing bush to wear and tear and causing the bearing bush temperature to rise rapidly.

how to troubleshoot

Before the motor stops, check the vibration of each part with a vibration meter, and test the vibration values in three aspects of vertical and horizontal axis for the parts with large vibration.

If the anchor screw or bearing end cap screw is loose, it can be tightened directly, and then vibration is measured to see if it is eliminated or mitigated.

Secondly, check whether the three-phase voltage of the power supply is balanced or not and whether the motor runs out of phase will not only cause vibration but also cause the motor to heat up rapidly.Observe whether the pointer of the power supply meter swings back and forth, and the rotor will swing when it is broken.Finally, check whether the three-phase current of the motor is balanced and stop the machine in time to avoid the motor burning.

If the vibration of the motor has not been solved after the surface phenomenon has been treated, the power supply must be disconnected to unlock the coupling.If the motor vibrates, the motor itself has a problem. In addition, the power-off method can be adopted to distinguish between electrical reasons and mechanical reasons.When the power is cut off, the motor will not vibrate or reduce vibration immediately, indicating that the electrical reason or the mechanical fault will be repaired according to the cause of the fault.

overhaul method

        First, determine whether the three-phase direct current resistance of the stator is balanced.If it is not balanced, it means that there is an open welding phenomenon in the welding part of the stator connecting line.Disconnect the winding phase to find out whether there is a turn-to-turn short circuit phenomenon in the other winding.If the fault is obvious, you can see scorching marks from the insulation surface, or measure the stator winding with an instrument.After confirming the turn-to-turn short circuit, the electric winding will be brought down again.

Secondly, check whether the air gap is even, if the measured value exceeds the standard, readjust the air gap, check the bearing, replace the bearing if the measured gap is not up to standard, check the deformation and looseness of the iron core, the loose iron core can be glued and filled with epoxy resin, check the rotating shaft, repair weld the bent rotating shaft to rework or directly straighten the shaft, and then perform the balance test on the rotor.

Again, there is no problem with the electrical system itself and the cause of the failure is caused by the connecting 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 whether the phase deviation of the motor shaft meets the requirements.