Grounding Device Boosts Reliability of HVAC/R Systems
April 2006
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The new AEGIS SGR™ Conductive MicroFiber™ Shaft Grounding Brush improves the reliability of HVAC/R systems by extending motor life. By protecting bearings from electrical damage for the life of the motor, the grounding brush helps prevent bearing noise, motor repairs and downtime.

AC motors are commonly used in HVAC/R systems to drive fans, air pumps, chillwater pumps, compressors, and other air-handling equipment. When employed with variable frequency drives (VFDs), currents are induced on the motor shafts. Without a grounding device, these currents typically discharge through the motor bearings, causing frosting, pitting, fusion craters, and fluting. This damage can lead first to noise that travels throughout a building’s ductwork, then to motor failure and finally to failure of the entire HVAC/R system. By safely channeling harmful shaft current away from the motor bearings to ground, the SGR prevents electrical bearing damage, and the noise and motor failures it causes.

The device is designed to be easily installed by sliding the brush over either end of the motor shaft and locking it in place with simple screw-on mounting brackets. Because no machining is required, it can be installed in minutes.

Unlike conventional shaft grounding brushes, which wear out quickly and lose their effectiveness, the AEGIS SGR’s conductive microfibers work with virtually no friction or wear and last for the life of the motor, with no RPM limitations. Maintenance-free, the device is said to be unaffected by dirt, grease or other contaminants.

The SGR is available in standard sizes to fit AC motors ranging from 1 horsepower (hp) to 1,500 hp with shaft diameters from 0.311 inches to 6.020 inches (8 mm to
153 mm). Larger sizes are available for shafts with diameters greater than 6 inches (152.40).

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