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INSTALLATION NOTES

Motors with shaft diameter less than 2" Motors with shaft diameter greater than 2" NEMA/IEC Kit Installation Instructions SGR Installation Instructions SGR Bolt Through Installation SGR Press Fit Installation

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AEGIS SGR™

Frequently Asked Questions

1. What makes the AEGIS SGR™ so reliable?
2. Why does the AEGIS SGR™ last so long?
3. What makes the AEGIS SGR™ so effective in discharging shaft current?
4. How long will the AEGIS SGR™ grounding brush last?
5. Why don't the fibers wear over time?
6. Is any maintenance needed for the AEGIS SGR™ once it is installed?
7. Is AEGIS SGR™ affected by oil or grease?
8. Do the AEGIS SGR™ Conductive MicroFibers™ touch the shaft?
9. Will AEGIS SGR™ remain equally effective during its long service life?
10. When should AEGIS SGR™ be replaced on the motor?
11. Will the AEGIS SGR™ cause wear to the shaft of the motor?
12. Why do conventional shaft grounding brushes wear out?
13. Why do conventional shaft grounding brushes need maintenance?
14. Should conventional copper shaft grounding brushes be replaced by AEGIS SGR™ ?
15. Where do the VFD shaft currents go with no brush installed?
16. Why are shaft currents so destructive?
17. What does bearing frosting look like?
18. What does bearing fluting look like?
19. What happens to the motor as frosting and fluting take place in the bearings?
20. Will electrical bearing damage always occur in a VFD application?
21. How about VFD duty motors, are they safe from bearing damage?
22. How about IEEE 841 motors, are they safe from electrical bearing damage?
23. We just installed VFDs on many of our motors and so far everything is OK, should I be worried about shaft current?
24. From a preventative maintenance perspective what would you recommend?
25. Can I operate the AEGIS SGR™ over the shaft keyway?
26. What is the wear rate of the micro fibers?
27. What is the best way to measure shaft voltage?
28. Can an RMS measurement be used to test for the presence of shaft voltages?
29. Will the AEGIS SGR™ work in washdown duty motor?
30. Should one or two AEGIS™ SGRs be installed on the motor?
31. If AEGIS SGR™ is installed outdoors, will water affect performance?
32. Does any corrosion occur to AEGIS SGR™ with water?
33. Is it possible to press the SGR into the motor housing instead of using the mounting brackets?

1. What makes the AEGIS SGR™ so reliable?
Answer: (1) The patented technology design ensures that there is a high density of discharge points provided by the Conductive MicroFiber™ all around the shaft to discharge the unwanted shaft currents to ground, (2) The AEGIS SGR™ is maintenance free and there is nothing to wear out, (3) The AEGIS SGR™ is designed to be effective in oil, grease or in a contaminated dusty environment.

2. Why does the AEGIS SGR™ last so long?
Answer: The patented technology design of the AEGIS SGR does not use applied pressure friction for the fibers and therefore there is no direct frictional wear applied to the fiber tips. The SGR will literally last for the service life of the motor.

3. What makes the AEGIS SGR™ so effective in discharging shaft current?
Answer: Because the optimum condition to discharge unwanted energy from a rotating shafts is created in the AEGIS SGR™ by completely surrounding the motor shaft with special conductive micro fibers. This is known as our patented technology Electron Transport Technology™ and ensures that potentially harmful shaft currents pass safely to ground.

4. How long will the AEGIS SGR™ Conductive MicroFiber™ shaft grounding brush last?
Answer: The AEGIS SGR™ will last for the normal service life of the motor and continue to discharge shaft currents.

5. Why don't the fibers wear over time?
Answer: There is no measurable wear. Even after 8700 hours of continuous operation the wear was not measurable with a micrometer. This is because of the patented technology design that ensures the perfect interference fit to the shaft surface.

6. Is any maintenance needed for the AEGIS SGR™ once it is installed?
Answer: AEGIS SGR™ technology is maintenance free and will not wear out. It is fully effective even in oil, grease or contamination.

7. Is AEGIS SGR™ affected by oil or grease?
Answer: AEGIS SGR™ is just as effective in an oily or greasy environment because the Conductive MicroFibers™ cut through the grease and oil and maintain their contact on the motor shaft to discharge the shaft currents.

8. Do the AEGIS SGR™ Conductive MicroFibers™ touch the shaft?
Answer: There is an interference fit to the motor shaft surface 360 degrees around the shaft so that the fibers are always touching. The patented technology design ensures that the discharges take place to protect the motor bearings.

9. Will AEGIS SGR™ remain equally effective during its long service life?
Answer: AEGIS SGR™ is designed not to wear out during the service life of the motor. This is because of the ultra-low friction of the fiber interference with the shaft.

10. When should AEGIS SGR™ be replaced on the motor?
Answer: Whenever the motor bearings are normally replaced we recommend that a new AEGIS SGR™ be installed at the same time as part of the normal maintenance.

11. Will the AEGIS SGR™ cause wear to the shaft of the motor?
Answer: The motor shaft will not wear because there is virtually no friction in the patented technology design and therefore there is no measurable wear of the shaft, even after over 8700 hours of continuous operation.

12. Why do conventional shaft grounding brushes wear out?
Answer: Whether metal bristle or carbon block, conventional shaft grounding brushes use a spring loaded mechanism to apply pressure onto the shaft while it is rotating. This causes rapid wear of the brush surface and frequent replacement.

13. Why do conventional shaft grounding brushes need maintenance?
Answer: Conventional metal or carbon brushes need frequent maintenance both to ensure they are free from oil or contaminants and to replace due to normal wear. Also the springs will weaken over time and require replacement.

14. Should conventional copper shaft grounding brushes be replaced by AEGIS SGR™ on VFD motors?
Answer: AEGIS SGR™ replaces conventional shaft grounding brushes, improves reliability, and decrease maintenance costs. Conventional shaft grounding brushes need frequent maintenance and become less effective over time. They rely on the spring tension to press the brush against the rotating shaft. This causes the brush, material to wear as it rubs on the shaft - sometimes in as little as 3 months. In addition, oil, grease, dirt or oxidation will break the conductive path and reduce or will reduce or prevent conventional brushes from discharging shaft currents.

15. Where do the VFD shaft currents go with no AEGIS SGR™ installed?
Answer: The shaft currents will build up on the motor shaft and discharge through the bearings. This happens because the voltages induced onto the motor shaft overcomes the dielectric of the grease film between ball and race.

16. Why are these shaft currents so destructive?
Answer: Because they occur literally millions of times per minute while the motor is running. Over time the bearing race becomes heavily frosted and mat start to flute in a very short period of time…sometimes causing failure in only a few months.

17. What does bearing frosting look like?
Answer: Frosting will look like a gray or white line along the bearing race where the discharges take place:

Image 1: Bearing frosting line

18. What does bearing fluting look like?
Answer: Fluting will look like a washboard pattern of Gary or white along the bearing race where the discharges take place:

Image 2: Bearing Fluting, the distinctive "washboard" pattern

19. What happens to the motor as frosting and fluting take place in the bearings?
Answer: Vibration and bearing noise will continue to increase as the problem gets worse. This noise, caused by the bearing ball coming in contact with the fluting or severe frosting of the bearing race is an indicator of potential catastrophic failure. Installing the AEGIS SGR™ will divert the currents which cause the bearing failures away from the bearings and will discharge the currents to ground.

20. Will electrical bearing damage always occur in a VFD application?
Answer: Yes - with no alternate path to discharge shaft current, pitting of the motor bearing will take place during VFD operation. These discharges will continue and will always seek the path of least resistance - usually through the motor bearings. Installing AEGIS SGR™ will create an alternate path for these discharges and divert current away from the motor bearings.

21. How about VFD duty motors, are they safe from bearing damage?
Answer: Electrical bearing discharges will occur even in VFD duty motors and must be addressed to avoid potential failures. Without a device like AEGIS SGR™ installed, the VFD induced shaft currents still discharge through the motor bearings and may eventually cause failure.

22. How about IEEE 841 motors, are they safe from electrical bearing damage?
Answer: No. All motors, including the NEMA 841 and premium efficiency motors will experience electrical bearing damage when operated by VFDs - unless they are protected from shaft current. AEGIS SGR™ NEMA kit installes to the motor end bell to clear the rotating portion of the bearing isolator.

23. We just installed VFDs on many of our motors and so far everything is OK, should I be worried about shaft current?
Answer: Yes - even if you have not experienced excess noise, vibration or bearing failure so far, the VFD induced shaft currents continuously discharge through the motor bearings during operation and may cause an unplanned failure unless you have a means to discharge them. By installing the AEGIS SGR™ Conductive MicroFiber™ shaft grounding brush, you will provide the best means of protection and prevention to avoid potential failure.

24. From a preventative maintenance perspective what would you recommend?
Answer: In order to prevent potential catastrophic failures, AEGIS SGR™ Conductive MicroFiber™ brush or the Inpro/Seal MGS bearing isolator.

25. Can I operate the AEGIS SGR™ over the shaft keyway?
Answer:The AEGIS SGR™ should not operate over the shaft keyway. SGR microfibers should not come in contact with the keyway during operation. Upon installation, you may slide the SGR over the keyway but the final installation should not be over the keyway.

26. What is the wear rate of the micro fibers?
Answer: The unique Conductive MicroFibers™ used in the AEGIS SGR™ are a very tough material and will not readily wear. Because of the patented technology design, there is virtually no friction to cause fiber wear like with conventional brush configurations.

27. What is the best way to measure shaft voltage?
Answer: The best measurements are taken with an oscilloscope by placing the probe in the middle of the end of the shaft - drive end or non-drive end and observing the shaft voltages.

28. Can an RMS measurement be used to test for the presence of shaft voltages?
Answer: Measuring RMS is not the best way to check for damaging voltages on the shaft but will indicate the presence of the shaft voltage. RMS "averages" the voltage reading and therefore does not show the voltage spikes that cause the electrical bearing discharges.

29. Will the AEGIS SGR™ work in washdown duty motor?
Answer: Yes, the AEGIS SGR™ works well in wash down duty motors because the fibers are not affected by water.

30. Should one or two AEGIS™ SGRs be installed on the motor?
Answer: For smaller frame motors with shaft diameters of less than 2" you will generally only need a single AEGIS SGR™ on the motor. This is because circulating currents are not present in these smaller motors. Any motor with larger than 2" shaft should have an SGR on both the drive end and non-drive end of the motor to discharge both VFD currents and circulating currents.

31. If AEGIS SGR™ is installed outdoors, will water affect performance?
Answer: There is no problem with water or moisture - AEGIS SGR will continue to perform even If some water gets inside AEGIS SGR™.

32. Does corrosion occur to AEGIS SGR™ with water?
Answer: Fresh water will not cause corrosion.

33. Is it possible to press the SGR into the motor housing instead of using the mounting brackets?
Answer: Yes, you can press fit the SGR into the motor housing instead of using the mounting brackets. The SGR has an OD tolerance of 0.02" (0.5mm) so you'll want to measure the SGR before boring out the motor end bell. We recommend a 0.003" to 0.004" crush fit between the bore and the SGR OD. This should be a clean dry press. No oil or other lubricants are to be used for press assist.

© 2007 Electro Static Technology, an ITW Company