Prevent VFD-Induced Bearing Damage in Water Treatment Systems

Water treatment facilities that rely on pumping systems need their motors to perform consistently. If a motor goes down, there may not only be considerable repair costs, but also a danger to public safety. One common mode of motor failure is premature bearing failure due to electrical bearing damage.

Although electrical bearing damage can occur in any motor, it is much more common in motors controlled by variable frequency drives (VFDs). VFDs can save 30% or more in energy costs, but they induce motor shaft voltage that damages bearings, causing premature failure. In fact, the total cost of repairing or replacing failed motor bearings can wipe out any savings that a VFD yields.

See how these facilities learned about the problems created by shaft voltage, and how to prevent repeat bearing failure.

Pump Systems

When a large midwestern US recreational center experienced bearing fluting damage to several pump motors, the facility’s manager realized that he needed to install bearing protection on the center’s VFD-driven motors. Not sure what product to use, he decided to conduct a head-to-head test on two technologies.

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Water Treatment

One Electrical Engineer learned the hard way. An ordeal concerning several inverter-controlled pump motors with bearing damage make him a believer in the need for shaft grounding.

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