High capacity motors on-line diagnosis based on ultra wide band partial discharge detection

A noninvasive ultra-wide band (UWB) partial discharge technique was employed in high capacity motors diagnosis. Those motors are installed and operating in an oil pumping plant. The technique presented here was applied to 13 motors rated at 13.8 kV and 2500 HP of capacity. The technique allowed motors insulation system status classification, according to UWB partial discharges activity measured and recorded on the cable feeders´ ground connection. The PD defection technique used, employs near field sensors (HF CT) working within the 80 MHz range and whose information is digitized and fed to a conventional PD digital detector, where a traditional N-Q-Φ PD pattern is obtained to facilitate motor insulation system problems identification. Those results of on-line evaluation of these motors, during normal operation, using UWB techniques are presented and discussed in the paper.