In recent years, the power industry has undergone rapid growth and a large amount of power equipment has flooded into the power system. How to ensure the safe and reliable operation of various types of power equipment has become a difficult problem in the whole industry. As a means of detecting and assisting maintenance of power equipment, on-line condition monitoring(CM) has been widely used in power generation, transmission, substation, distribution, consumption and other fields in the past few decades. This paper reviews current on-line condition monitoring techniques, (i.e. dissolved gases in oil analysis(DGA), partial discharge, etc.) and development trends of condition monitoring. As more and more on-line monitoring methods of non-electrical quantity like vibration, ultrasound and pressure flourish these years, on-line condition monitoring system is extending from single parameter to multiple parameters, from electrical quantity to multiple physical quantities, from isolated to comprehensive, from centralized to networked, Internet of Things. In the context of ‘Ubiquitous Internet of things’, on-line condition monitoring is surely a promising way towards reliable protection of electrical equipment. However, in spite of obvious progress and undoubted benefits, the on-line condition monitoring system has also experienced a large number of practical problems in the application process such as generally low data availability and reliability. Furthermore, statistics on CM-related standards at home and abroad show a dramatic blank in international standards of CM. Therefore, there is an urgent need that the international standards for condition monitoring should be set up as soon as possible. Corresponding areas for further research are also presented such as uncertainty evaluation, error modeling and evaluation system based on sequential control. It is intended that this review will provide the basis for future developments of safe and reliable on-line conditon monitoring system.

On-line condition monitoring,protection,standards,review