Tom Bishop, P.E.
EASA Technical Support Specialist
Mechanical resonance can be defined as the amplification of the vibration level of a mass or structure at its natural frequency, caused by excitation from an external source. For a rotating mass, this amplification occurs at the critical speed(s). Electrical resonance causes an amplification of the magnitude of voltage or current, or both. The increase in amplitude, whether mechanical or electrical, increases the stress on motor components and negatively affects operation, e.g., increased vibration, instability, increased energy consumption, and premature failure.
By receiving energy from an external source, the resonant condition can cause the magnitude of the disturbance to continue to increase until a fault occurs. Mechanical resonance can lead to breakage of motor and drive components, and electrical resonance can result in winding failure. In this article we will discuss mechanical and electrical resonance associated with motors and drives, and provide some solutions to address them.
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