On line condition monitoring of HV electrical rotating plant. A comparison of techniques

As strategic plant becomes more cost important, pressure on improved reliability and the need to reduce maintenance costs results in the greater need for adopting effective online condition monitoring strategies. This is even more important for electrical rotating plant-generators and HV motors-which, in service, impose on the HV stator insulation a combination of stresses electrical, mechanical and thermal. These can, if their effects are not identified in early stage of initiation, result in rapid and premature failure of the HV stator insulation. Over the past 10 years a number of online techniques have been developed for monitoring the partial electrical discharges which are produced from the deterioration which may develop. This paper considers three techniques which have been developed, describes their application and gives an example of comparative sensitivity tests which were carried out to assess their comparative effectiveness in detecting electrical partial discharges (PD) generated in service, in the HV stator insulation of HV motors and generators