Damage Condition Possible Causes Countermeasures

When electric current passes through a bearing, arcing and burning occur through the thin oil film at points of contact between the raceway and rolling elements. The points of contact are melted locally to form "fluting" or groove-like corrugations which can be seen by the naked eye.
Magnification of these grooves reveals crater-like depressions which indicate melting by arcing.

Electric current passing through a bearing

  • Design electric circuits which prevent current flow through the bearings
  • Insulate the bearing