Partial Discharge Monitoring
Partial discharges (PD) are small electrical current sparks that occur in the high voltage electrical insulation in stator windings whenever there are small air gaps or voids in or on the surface of the insulation. As a stator winding deteriorates from coil winding vibration in the slot, operation at high temperatures, or contamination, the partial discharge activity increases. Thus partial discharge monitoring can be used to detect the primary causes of stator winding failure and generally give two or more years of warning of a machine failure.
