Motor Repair

Protecting VFD-Driven Motors

VFD-Induced Bearing Currents Kill Motors!
Today, variable frequency drives (VFDs) are commonly used to control the speed of motors. They not only provide precise process control for improved productivity and product quality, but they also save energy. But VFDs can also damage motors. They create voltages on motor shafts that discharge through the bearings, causing pitting, fluting, and in many cases catastrophic motor failure. Without bearing protection, any savings from the use of VFDs can be quickly wiped out by system downtime and the cost of replacing motors.

AEGIS® Shaft Grounding Rings Protect Bearings
If a motor is worth repairing, it is also worth protecting from VFD-induced shaft voltages that can cause premature bearing failures and unwanted downtime. AEGIS Shaft Grounding Rings divert destructive currents away from the bearings safely to ground, making motor-driven systems truly sustainable.

AEGIS Rings for Any Application
No matter the type or size motor or where it is used, there is an AEGIS Ring available to protect it from bearing damage. And motor service and repair shops are experts in the selection of the best AEGIS Ring for any application as well as in the best practices for its installation.

  • NEMA and IEC Low-Voltage Motors up to 100 hp: Install AEGIS SGR inside or outside the motor
  • Medium-Voltage Motors, and Low-Voltage over 100 hp: Install AEGIS PRO Series Rings to protect bearings of motors with shafts to 30" diameter

ABCs of Bearing Inspection Paper
Remember to follow the ABCs of bearing inspection

Presented with EASA's permission.
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St Louis, MO USA. All rights reserved.