Development and Experiment of Insulation Flaw Locating Device for Large Horizontal Motor

Strong partial discharge (PD) activities are generally present in large horizontal generators (
$\ge 25$
MW and
$\ge 6$
kV) that run continuously for long periods. The maintenance and safe functioning of the large motors depend on the location of the offline PD problem. The mechanical equipment that can be utilized to find insulation flaws is designed in this study. First, a highly sensitive wideband directional antenna is designed to pick up electromagnetic signals from PDs. Furthermore, a mechanical vehicle that can be remotely controlled and used with a variety of horizontal motors (different inner diameters) is developed. To detect the flaw and flaw position coordinates, the vehicle transmits synchronous voltage signals and PD signals in real time. Furthermore, it computes the phase-resolved PD (PRPD) and discharge average or maximum magnitude, distance, and angle (MDA) maps. Finally, to confirm the reliability of the rotating system, we produce four different bars of typical flaws in the horizontal motor. Thus, the rotating system identifies and locates the insulation type and coordinates of the flaws for large horizontal motor bars, which can be applied to
$\ge 25$
MW and
$\ge 6$
kV motors for testing in the future.