Rock Products

NOV 2012

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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MAINTENANCE Shaft Grounding Ring Protects Motors And Generators By Mark S. Kuhar The Aegis iPRO Bearing Protection Ring from Electro Static Technology extends the life of medium‐voltage motors and improves the reliability of systems in which they are used by safely channeling harmful electrical currents away from bear‐ ings to ground. Specially designed for high‐current applica‐ tions, the Aegis iPRO is ideal for protecting generators, turbines and medium‐voltage motors against electrical bear‐ ing damage. The rugged, highly reliable, and maintenance‐free Aegis iPRO prevents damage that could otherwise lead to generator or motor failure, unplanned downtime, costly repairs, and lost revenues. It is available in a range of sizes to accommodate generator/motor shafts up to 30‐in. in diameter. To facilitate field retrofits, the iPRO split‐ring comes in mating halves that simplify installation around the shafts of coupled equipment. Common sizes (for motor shafts between 2.5‐in. and 12‐in. in diameter) are typically shipped within five days. If not diverted, shaft voltages induced by variable frequency drives (VFDs) discharge through the bearings of motors, gen‐ erators, and coupled equipment. Embedded securely in the Aegis FiberLock channel along the inner circumference of the iPRO, six rows of conductive microfibers completely surround the motor shaft, providing millions of discharge points for harmful shaft currents and creating the path of least resist‐ ance that effectively diverts these currents away from bear‐ ings to ground. The Aegis iPRO is ideal for medium‐voltage motors that drive pumps, compressors, mixers, shredders, conveyors, and other machinery used in mining, food processing, wastewater treat‐ ment, petrochemical refining and many other applications. It is also ideal for protecting the bearings of generators in both utility and on‐site power generation systems. Compatible with current‐monitoring equipment, the Aegis iPRO is a long‐lasting and effective shaft grounding device. It is engineered to safely divert high‐current and high‐fre‐ quency dv/dt shaft currents and works even in the presence of oil, dirt, grease or other contaminants. As part of a preven‐ tive maintenance program, it can be installed whenever bear‐ ings are replaced. Easy Retrofitting The new split universal mounting kit version (Split uKIT) of the Aegis SGR Bearing Protection Ring protects the bearings of VFD‐driven motors from electrical damage, and allows 44 ROCKproducts • NOVEMBER 2012 quick and easy retrofitting of the ring on virtually any AC motor shaft without decoupling attached equipment. The Split uKIT is ideal for plant maintenance departments. Designed to accommodate slingers, shaft shoulders, and other end bell protrusions, the kit comes with a split Aegis ring, the halves of which are held together with a unique hinge. This hinge design allows the split Aegis ring to be opened on one side, then closed and fastened together with built‐in adhesive backed aluminum tabs, providing rigidity to the assembled ring. Ordered based on a motor's frame size, the kit includes the correct size split Aegis grounding ring and mounting hardware – screws, washers, Allen wrenches, and four styles of brackets, for use in a wide range of combinations to facili‐ tate mounting of the ring on virtually any NEMA or IEC motor faceplate. The brackets can be attached either by drilling and tapping small holes or by applying Aegis Conductive Epoxy (sold separately). Aegis rings prevent electrical bearing damage, costly motor repairs/replacements, and downtime by safely channeling VFD‐induced bearing currents to ground. Continuous circum‐ ferential rows of conductive microfibers are embedded se‐ curely in the ring's patented Aegis FiberLock channel, completely surrounding the motor shaft and providing mil‐ lions of discharge points for harmful shaft currents. Electro Static Technology, www.est‐aegis.comE

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