All major manufacturers of 3-phase AC induction motors offer “inverter-duty” or “inverter-ready” models, but while these motors have inverter-rated insulation to protect the windings, their most vulnerable parts — the bearings — are too often ignored. Without some form of mitigation, shaft currents can discharge through bearings, causing motor failure and downtime. To be considered truly “inverter-ready”, a motor must have proven long-term bearing protection — an AEGIS® Shaft Grounding Ring — in addition to inverterrated insulation. Unfortunately, many purchasers of these motors do not understand this. And, mission-critical facilities, in which downtime can have disastrous consequences, are especially vulnerable to motor failures.
Recognizing that the best solution is to design motors from the ground up to survive the damaging effects of VFDs, a growing number of forward-looking motor manufacturers have recently added factory-installed AEGIS® Bearing Protection Rings as standard or optional features on certain models.
