Pro Tip: Installing a direct contact or non-contact grounding ring can reliably protect bearings from electrical discharges that cause pitting, frosting and fluting damage.
Several years ago, I was involved in the investigation of three 150-hp air compressor motor failures on somewhat new units. During our investigation, we learned that the motor bearings were all in varying stages of failure due to electrical discharges that caused pitting, frosting and fluting.
You can protect your high horsepower motors powered by variable frequency drives (VFDs) or inverters from early failure by installing grounding rings to protect the bearings.
This issue can happen with fractional horsepower motors powered by VFDs as well, but it becomes more necessary to prevent on costly applications like mixer drives, compressors or any other critical assets powered by a VFD and driving a high-powered motor.
VFDs by nature change the AC incoming power to a square wave DC signal and modify it in a way that allows the speed or frequency of the motor to be adjusted. During this process, static discharges can be passed from rotor to stator by way of the bearings and the grease contained inside. This can contaminant the grease and pit bearing race(s) or the ball bearings.
By installing a direct contact or non-contact grounding ring like the AEGIS Shaft Grounding Ring technology, you can reliably protect bearings from electrical discharges that cause pitting, frosting and fluting damage. The good news is that, in many applications, a grounding ring can be installed without removing or the disassembly of the motor.
For a visual demonstration of these static discharges, click here: https://youtu.be/1L-phyVXQkI.
To see an example of how easy a shaft grounding ring can be installed, click here: https://youtu.be/QJKwPA_WhlM.
Rowdy Brixey is founder and president of Brixey Engineering Inc.
You can connect with him on LinkedIn.