Like all other machinery and equipment, motors undergo various physical and chemical parameters such as energy, heat, wear, and vibration during operation. These changes in information directly and indirectly reflect the operating status of the motor, and vibration can sensitively reflect the operating status of the motor. There are many factors that can cause motor vibration, including quality issues with the motor itself, compatibility issues between the motor and equipment, as well as practical operating conditions, and so on.
As for the motor body, controlling the processing of components, fixing of windings, dynamic balancing of rotors, and coordination of components can ensure that the inherent mechanical vibration characteristics of the motor meet the requirements. In addition to vibrations caused by mechanical factors, vibrations caused by electrical reasons are also common, such as vibrations caused by uneven air gaps between the stator and rotor, axial displacement caused by misalignment of the stator and rotor cores, resonance caused by power frequency, and so on. The analysis of vibration caused by electrical factors may be directly judged by cutting off the power supply.
Analysis of the causes of motor vibration:
●Uneven rotor, coupler, coupling, and transmission wheel can cause unevenness.
●The iron core bracket is loose, the inclined joint and pin are ineffective and loose, and the winding is loose.
●The rotor is not tightly tied and the rotor balance is not good, causing the rotating parts to be unbalanced.
●The linkage system is not centered, the centerline is not aligned, and the centering is incorrect. The main cause of this malfunction is poor alignment and improper installation during the installation process.
●The center line of the linkage part is coincident and consistent in the cold state, but after running for a period of time, vibration occurs due to deformation of the rotor fulcrum, its foundation, etc., and damage to the center line.
●Malfunctions in the gears and couplings connected to the motor, poor gear engagement, severe tooth wear, skewed or misaligned couplings, incorrect tooth profile and pitch, excessive clearance, or severe wear of gear couplings can all cause certain vibrations.
●Defects in the structure of the motor itself, such as elliptical shaft neck, bent shaft, excessive or insufficient clearance between the shaft and the bearing shell, insufficient stiffness of the bearing seat, foundation plate, certain parts of the foundation, and even the entire motor installation foundation.
●The fixing between the motor and the base plate is not firm, the foot bolts are loose, and there is looseness between the bearing seat and the base plate.
●Excessive or insufficient clearance between the shaft and the bearing shell can not only cause vibration but also lead to abnormal lubrication and temperature of the bearing shell.
●The load driven by the motor conducts vibration. For example, the vibration of fans and water pumps driven by motors can cause motor vibration.
●Wrong stator wiring of AC motor, short circuit of rotor winding of wound asynchronous motor, short circuit between turns of excitation winding of synchronous motor, incorrect circular connection of excitation wire of synchronous motor, broken bar of rotor of cage asynchronous motor, deformation of rotor iron core causing uneven air gap between stator and rotor, resulting in unbalanced air gap magnetic flux and vibration.
