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

Bearing frosting line on bearing race
What does bearing fluting look like?
Answer: Fluting will look like a washboard pattern of grey or white along the bearing race where the discharges take place:

Bearing Fluting, "washboard" pattern on bearing race
Why are these shaft currents so destructive?
Answer: Because when motors are controlled by VFDs, they occur literally millions of times per minute while the motor is running. Over time the bearing race becomes heavily frosted and may start to flute in a very short period of time ... sometimes causing failure in only a few months.
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.
What makes the AEGIS SGR so reliable?
Answer: (1) The patent pending design ensures there is a high density of discharge points provided by the Conductive MicroFiber™ around the entire circumference of the shaft, diverting 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.
Why does the AEGIS SGR™ last so long?
Answer: AEGIS SGR™'s patent pending design applies virtually no frictional pressure of the fibers to the shaft and therefore there is no direct frictional wear applied to the fiber tips. The SGR will literally last the service life of the motor.
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 patent pending Electron Transport Technology™ and ensures that potentially harmful shaft currents pass safely to ground.
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.
Why don't the fibers wear over time?
Answer: The patent pending design ensures there is virtually no friction and therefore no wear. After 8700 hours of continuous testing the wear was not measurable with a micrometer.
Is any maintenance needed for the AEGIS SGR™ once it is installed?
Answer: AEGIS SGR™ technology is maintenance free and will not wear out. The special Conductive MicroFibers™ are extremely tough and will last for the service life of the motor.
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 shaft currents.
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. The patent pending design ensures that the discharges take place to protect the motor bearings when the AEGIS SGR™ is installed properly.
Will AEGIS SGR™ remain equally effective during its long service life?
Answer: Yes - AEGIS SGR™ is designed not to wear out during the service life of the motor. This is because of the ultra-low friction between fiber and shaft which ensures long life while discharging takes place.
When should AEGIS SGR™ be replaced on the motor?
Answer: Even though AEGIS SGR™ lasts for the service life of the motor, it is a good idea to replace the SGR at the same time the motor bearings are normally replaced.
Will the AEGIS SGR™ cause wear to the shaft of the motor?
Answer: The motor shaft will not wear because there is virtually no frictional force applied to the shaft. Therefore there is no measurable wear of the shaft, even after over 8700 hours of continuous operation.
Why do conventional shaft grounding brushes wear out?
Answer: 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 "stick-slip" and rapid wear of the brush surface and leads to frequent replacement.
Why do conventional shaft grounding brushes need maintenance?
Answer: Conventional metal or carbon brushes need frequent maintenance to ensure they are free from oil or other contaminants. Mechanical stress will cause springs to weaken.
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 as little as 3 months. Oil, grease, dirt or oxidation will break the conductive path and will reduce or prevent conventional brushes from discharging shaft currents.
Where do the VFD shaft currents go without a brush installed?
Answer: The shaft currents will build up on the motor shaft and discharge through the bearings. This occurs because voltages are induced onto the motor shaft overcomes the dielectric of the grease film between ball and race.
Will electrical bearing damage always occur in a VFD application?
Answer: Yes - without an alternate path to discharge shaft current, pitting of the motor bearing will take place during VFD operation. Discharges will continue and will always seek the path of least resistance - commonly through the motor bearings. Installing AEGIS SGR™ will create an alternate path for discharges and divert current away from the motor bearings.
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 the AEGIS SGR™ installed, the VFD induced shaft currents will discharge through the motor bearings and may eventually cause failure.
How about IEEE 841 motors, are they safe from electrical bearing damage?
Answer: 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. Inpro Seal's MGS bearing isolator combines the AEGIS SGR™ technology with the bearing isolator. These motors may be easily retrofitted for shaft current protection by replacing the standard Inpro Seal bearing isolator with the MGS bearing isolator.
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 there is 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 unplanned motor failure.
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 should be installed on both sides of large motors and a single SGR or MGS for small motors.
Our AEGIS SGR™ is installed over the shaft keyway, is this a problem?
Answer: Positioning the AEGIS SGR™ over the shaft keyway is not a problem because the fibers are flexible enough to bend over the keyway and function properly.
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 patent pending design, there is virtually no frictional pressure to cause fiber wear as with conventional brush configurations.
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.
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 shaft voltages, however it does indicate their presence. RMS "averages" the voltage reading but does not show the voltage spikes that cause the electrical bearing discharges.
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 effected by water.
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 need a single AEGIS SGR™ on the motor. This is because circulating currents are not present in smaller motors. Any motor with larger than 2" shaft should have an SGR on both the drive end and non-drive end to discharge both VFD currents and circulating currents.
If AEGIS SGR™ is installed outdoors, will water affect performance?
Answer: There is no problem with water or moisture - AEGIS SGR will perform despite the presence of water inside AEGIS SGR™.
Does corrosion occur to AEGIS SGR™ with water?
Answer: Fresh water will not cause corrosion, if operated in a corrosive environment then you must specify a stainless steel AEGIS SGR™.