A portable partial discharge measuring system for insulation condition monitoring

Abstract

A portable partial discharge (PD) measuring system, which uses novel PD sensors and a handheld digital storage oscilloscope (DSO), has been developed and used for on-line assessment and monitoring of the insulation condition of large machines and other apparatus. The PD sensors use high voltage high frequency current transformers (HVHFCT). These are small and non-intrusive and thus can be installed at several positions in a machine terminal without opening the machine. The DSO is available off-the-shelf at low cost. It can be carried to different plants and connected to both PD sensors in a machine, and controlled via a laptop personal computer (LPC), for PD measurement, processing, and communication for remote insulation assessment and condition monitoring. This effective, convenient, and widely applicable technique has also been used to assess the insulation of cables and busbars. The simplicity of the portable PD measuring system is shown in this paper. Means of using the techniques for insulation assessment of large machines, high voltage cables, and busbars will also be introduced.