Culver Armature and Motor

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New Products Field Installable Shaft Ground Ring Kits From Marathon

Field Installable Shaft Ground Ring Kits From Marathon


Beware Bearing Currents….Marathon Electric Announces “SGR”

Tired of premature bearing failures? too! It gives me great pleasure to introduce the Shaft Ground Ring or SGR, the latest innovative product addition to our extensive line of field installable kits. Given the fact that we are the leaders in Variable Frequency Drive (VFD) motors with the MAX motor family, it should be no surprise that we have raised the bar again with this new solution to a very real problem with VFDs. We have spent hundreds of hours testing and understanding the interaction between the VFD and the AC induction motor, we discovered that the problem exists with all VFDs and all the motors they control. While VFDs deliver impressive energy savings (up to 30% or more), they also introduce harmful common mode voltages (CMV) onto the shaft of those motors. The resulting currents will damage motor bearings, which result in costly downtime and premature motor failure. Any truly “green” process must achieve sustainability as well as energy efficiency. The SGR kits make this possible by dramatically extending the lives of motors controlled by VFDs.

The SGR can be included to a build-up Marathon Electric motor during assembly or added through Mod Central. These kits are designed to be a retro fit for all Marathon Electric NEMA T or TS shaft, non flanged motors. They are easily installed, usually within minutes. Unlike conventional grounding brushes, the SGR is maintenance-free and works with virtually no friction or wear for the service life of the motor. The SGR kit incorporates a shaft ground ring, an adhesive ring, two screws, grounding pig tail and mounting instructions. Included with this letter is a PowerPoint presentation, installation instruction sheet and a catalog page. The PowerPoint is very helpful to understand the problem and solution. Typical uses are any VFD controlled motor with a NEMA T or TS shaft and standard drive end bracket. Feel free to call me with additional SGR or stub shaft kit potential capabilities or additional modifications.


Last Updated on Wednesday, 11 August 2010 11:32 


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