What is EDM (Electrical Discharge Machining)?
- The pulses to the motor from the VFD create a capacitively coupled common mode voltage on the motor shaft
- The voltage looks for a path to ground, breaks down the dielectric in the bearing. The voltages arc through the bearings, and electrical discharge machining (EDM) creates thousands of pits
- Bearings degrade, resulting in increased friction and noise
- Eventually, the rolling elements can cause fluting damage to bearing races
- Bearing lubrication/grease deteriorates, is burnt and fails
- Potential for costly unplanned downtime
Image of a bearing affected by EDM.
How is it measured.
The severity is measured using a Scope Meter, voltage probe and AEGIS® SVP Shaft Voltage Probe Test Kit.