Dealing with shaft currents
what can you do?
Using absorbing filters (such as common mode chokes or nanotech filters) in combination with a shaft grounding ring provides a robust defense against VFD-induced shaft currents. These solutions work synergistically: the filter absorbs high-frequency common-mode currents at the source (VFD output), while the shaft grounding ring safely diverts any residual shaft voltage to ground, bypassing the bearings entirely. This dual approach is especially effective in preventing EDM fluting, pitting, and premature bearing failure.
Fluted bearing Fluted bearing zoomed in
Things to know about grounding rings:
We sell both the Aegis and the Worldwide shaft grounding rings.
How long do they last?
The proprietary conductive microfibers are engineered to last over 200,000 hours, which typically exceeds the L10 life (rated life) of the motor bearings themselves. Wear is minimal, often cited as less than 0.001 inches over 10,000 hours due to virtually zero friction.
How often should I change them?
Manufacturers recommend replacing the grounding ring whenever the motor bearings are changed. Since the ring is designed to outlast the bearings, a replacement is usually only necessary during major motor maintenance or if the fibers show visible damage.
What shortens the life of a grounding ring?
Environmental Contaminants: Dust, oil, grease, or moisture can clog the microfibers, reducing conductivity.
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Physical Damage: Improper installation, excessive shaft runout, and improper contact during other maintenance can damage the fibers.
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Shaft Condition: Rust, paint, or debris on the shaft surface can accelerate fiber wear or prevent proper contact.
