How Mechanical Vibration Harms Electric Motor Winding Reliability

The Adverse Impact of Mechanical Vibration on Motor Winding Reliability

Electric motors are inherently complex electromechanical devices, where mechanical performance and electrical characteristics are intricately intertwined. While electrical aging and thermal aging are well-known threats to winding integrity—stemming from factors like excessive temperature rise and poor power supply quality—mechanical vibrations during motor operation are often overlooked but can be equally damaging.

One of the key purposes of the winding insulation and varnish curing process is to reinforce both electrical insulation between conductors and the mechanical integrity of the windings. By impregnating and curing the insulation system, the winding becomes a solid, cohesive unit. This rigidity ensures that all conductors remain relatively static during operation. Even if the motor is installed on a vibrating base, the fixed position of the conductors prevents friction, displacement, and insulation breakdown between windings.

However, in real-world applications, vibrations, voltage spikes, and sudden load changes often trigger a chain reaction that affects the entire motor system. The windings and associated insulation materials are not immune to mechanical stress. The slot openings of the stator core and the winding end-turns—areas with more spatial freedom—are particularly vulnerable. Under the influence of electromagnetic forces, these regions may undergo torsional oscillation. If the varnish impregnation is insufficient, such vibrations can severely compromise the insulation between windings, between phases, and even between turns, drastically increasing the risk of electrical failure.

During motor winding production, any mechanical deformation of insulation materials must be strictly avoided. Common issues like bending, delamination, or over-compression of composite insulation can reduce mechanical strength and degrade insulation performance. This is especially critical during slot insertion, where high slot fill factors may easily lead to damage at the slot liners. For variable frequency motors, mechanical vibration may also introduce micro air gaps within the windings, significantly increasing the likelihood of partial discharge and further deteriorating the operational reliability.

Whether it stems from external vibration sources or internal electromagnetic forces, mechanical vibration influences more than just the motor’s stability—it directly affects the durability and performance of the insulation system. Therefore, when designing motor insulation structures, accounting for mechanical vibration and electromagnetic forces must be a top priority.