www.powertransmission.com/articles/516-bearing-protection-needed-if-inverter-duty-motors-are-to-live-up-to-their-name
Bearing Protection Needed if Inverter-Duty Motors Are to Live up to their Name
August 1, 2012
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, the bearings--their most vulnerable parts--are too often ignored.