Variable Speed Drive Motors

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Variable speed drive motors, also known as inverter-duty motors, are an asset in the industrial manufacturing world. When using a variable speed drive, variable speed drive motors are less likely to fail during production than general purpose motors. Variable speed drive motors exceed general purpose motors in performance, because variable speed drive motors are manufactured to operate at low speed (RPM) without overheating during production.

Variable speed drives generate high voltage spikes in all electric motors. Variable speed drive motors withstand the high voltage
spikes that are generated by variable speed drives, whereas general purpose motors do not. General purpose motors do not have the insulation required to withstand high voltage spikes, so the motor winding on a general purpose motor used with a variable speed drive begins to breakdown, and ultimately, the winding will burn up.

Variable speed drives used on electric motors that are 100hp (or greater) induce harmful voltage levels on the electric motor shaft. When harmful voltage levels exceed the resistance of the motor bearing lubricant, those voltage levels dissipate to the electric motor’s bearing housings. Harmful voltage levels sent to a motor’s bearing housings eventually leads to bearing failure in the electric motor. Variable speed drive motors use special bearings that are designed to withstand the harmful voltage levels that are induced by variable speed drives.

General purpose electric motors can be driven by variable speed drives, but once the general purpose motor fails, an inverter duty motor should replace the general purpose motor. Precision Electric recommends maintenance technicians who use general purpose motors on variable speed drive applications to keep a spare inverter-duty motor to minimize downtime.

Variable speed drive motors are more expensive than general purpose motors, but the increase in cost is worth preventing
downtime in variable speed drive applications when low speed is present.Many variable speed drive applications do not need to operate at low speeds, so variable speed drive motors are cost-prohibited in applications where low speed is not required.

Call Precision Electric for free quotes on variable speed drives, variable speed drive motors, servo motors, and all other industrial related equipment. Precision Electric offers free repair quotes on all industrial electronics equipment and industrial electronics field services.