Washdown motors are specially designed and built to survive the contaminants, humidity, high-pressure spray, and cleaning chemicals of washdown environments. They are well-protected against threats from the outside that could damage them. But many washdown motors are less-protected against threats from the inside — threats like VFD-induced bearing damage.
By controlling the speed of motors, VFDs provide a flexible, cost-effective means of controlling processes. But VFDs can also damage motors. VFDs induce voltages on the shafts of the motors they control. Without effective bearing protection, these voltages can discharge through motor bearings (and often through the bearings of pumps, compressors, fans, conveyors, and other coupled equipment), destroying them in as little as a few months.
And since many washdown motors are used in continuous processing applications such as food, chemicals, pulp and paper, blast furnaces, wastewater treatment, metal smelting, natural gas processing, etc., replacing a motor with damaged bearings may require shutting down an entire production line or facility, costing hundreds of thousands, or even millions, of dollars in lost production. In the case of food processing, such shutdowns require the disassembly, cleaning, and sterilization of machinery before the line is restarted to prevent bacterial contamination of the food being processed. This further adds to the length and cost of these shutdowns.
AEGIS® Shaft Grounding Rings protect motors from VFD-induced bearing damage. AEGIS rings install around the motor shaft, with their conductive microfibers in contact with the shaft. These microfibers divert damaging currents away from bearings and safely to ground, and are proven to withstand over 200,000 hours of continuous operation. They are locked securely in place by AEGIS's patented, protective FiberLock™ channel, which helps protect them from excessive dirt, oil, grease, and other contaminants.
For convenience, AEGIS rings are usually installed externally (on the motor's faceplate). But for washdown applications, installing the rings inside the motor (on the bearing retainer) affords an extra measure of protection against high-pressure spray. If an AEGIS ring must be installed externally on a washdown motor, we recommend protecting it with an O-ring or V-slinger.
The easiest way to protect a washdown motor against VFD-caused bearing damage is to make sure it comes with AEGIS shaft grounding factory-installed. LEESON recently introduced its new line of Extreme Duck Ultra Washguard™ Industrial-Duty Washdown Motors with AEGIS Shaft Grounding Rings installed internally. For more information on these motors, click here.