Causes of explosion-proof motor vibration_Solutions when explosion-proof motor vibrates

The harm of explosion-proof motor vibration

Explosion-proof motors generate vibrations, which will shorten the life of winding insulation and bearings, affect the normal lubrication of sliding bearings, and the vibration force will cause the insulation gaps to expand, allowing external dust and moisture to invade, resulting in reduced insulation resistance and increased leakage current, and even causing insulation breakdown and other accidents.

In addition, the vibration generated by the motor can easily cause the cooler water pipes to crack and the welding points to vibrate open. At the same time, it will cause damage to the load machinery, reduce the accuracy of the workpiece, cause fatigue of all mechanical parts that are vibrated, and cause the anchor screws to loosen or break.

The vibration of the motor will cause abnormal wear of the carbon brushes and slip rings, and may even cause serious brush fire and burn the insulation of the collector ring. The motor will produce a lot of noise. This situation also occurs frequently in DC motors.

Causes of explosion-proof motor vibration

1. Electromagnetic reasons

1. Power supply: the three-phase voltage is unbalanced and the three-phase motor runs in a missing phase.

2. Stator: The stator core becomes elliptical, eccentric, and loose; the stator winding is broken, grounded, short-circuited between turns, connected incorrectly, and the three-phase current of the stator is unbalanced.

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

2. Mechanical reasons

1. Explosion-proof motor itself

The rotor is unbalanced, the shaft is bent, the slip ring is deformed, the air gap between the stator and rotor is uneven, the magnetic center of the stator and rotor is inconsistent, the bearing is faulty, the foundation is poorly installed, the mechanical structure is not strong enough, there is resonance, the anchor screws are loose, and the motor fan is damaged.

2. Cooperation with coupling

The coupling is damaged, the coupling connection is poor, the coupling center is not accurate, the load is unbalanced, the system resonates, etc. The linkage shaft system is not centered, the center line does not overlap, and the centering is incorrect. The main cause of this failure is poor alignment and improper installation during the installation process.

There is another situation, that is, the center lines of some linkage parts are consistent when cold, but after running for a period of time, the center lines are destroyed due to deformation of the rotor fulcrum, foundation, etc., resulting in vibration.

3. Reasons for mixing explosion-proof motors

1. The vibration of explosion-proof motors is often caused by uneven air gap, which causes unilateral electromagnetic pulling force, and the unilateral electromagnetic pulling force further increases the air gap. This electromechanical mixed effect manifests as motor vibration.

2. The motor axial movement is caused by electromagnetic pulling force due to the rotor's own gravity or installation level and the wrong magnetic center, which causes the motor axial movement, resulting in increased motor vibration. In severe cases, the shaft wears the bearing root, causing the bearing temperature to rise rapidly. The gears and couplings connected to the motor are faulty. This fault is mainly manifested in poor gear engagement, severe wear of gear teeth, poor lubrication of the gears, skewed and misaligned couplings, incorrect tooth shape and pitch of the gear coupling, excessive clearance or severe wear, which will cause certain vibrations.

The motor's own structural defects and installation problems. This kind of fault is mainly manifested in the oval of the shaft neck, the bending of the rotating shaft, the gap between the shaft and the bearing bush is too large or too small, the rigidity of the bearing seat, the base plate, a part of the foundation or even the entire motor installation foundation is insufficient, the motor and the base plate are not fixed firmly, the foot bolts are loose, the bearing seat and the base plate are loose, etc. The gap between the shaft and the bearing bush is too large or too small, which can not only cause vibration, but also cause abnormal lubrication and temperature of the bearing bush.

3. Load transmission vibration driven by explosion-proof motor

Solution to vibration caused by explosion-proof motor

First check the impact of surrounding components on the explosion-proof motor, then untie the coupling and let the explosion-proof motor run idle. If there is no vibration when running idle, it means that the vibration is caused by the misalignment of the center line of the explosion-proof motor shaft and the mechanical load shaft, or the failure of the mechanical load.

If the explosion-proof motor still vibrates when idling, it is caused by the explosion-proof motor itself. You can cut off the power supply before judging. If the vibration disappears immediately after the power is cut off, it is electromagnetic vibration. The fault may be a broken wire in the parallel branch of the winding, damaged bearings, uneven air gap, etc. If it still vibrates after the power is cut off, it is mechanical vibration, such as rotor imbalance, bearing damage, etc.