Overview of diagnostic and condition monitoring techniques for in-service power apparatus

Power apparatus condition monitoring, continually or at intervals, is important for any power transmission and distribution utility to supply energy with an acceptable level of reliability, quality and safety. Based on the information, critical and cost effective maintenance and repair decisions could be taken to reduce power failures and the resulting damage to infrastructure. The insulation material used in such systems degrades due to thermal, oxidative, hydrolytic, electrical and mechanical operating conditions. Also, a significant number of power apparatus in any power grid are currently operating beyond their design life. Operating health condition and remaining life are diagnosed by various offline and online monitoring techniques with expert systems. In this paper, the current status of R&D work in this field and the readily available commercial instrumentation based on electrical, chemical and mechanical methods are presented.