Offline condition assessment of the insulation in HV equipment is applied extensively in order to minimize the possibility of failure in service. However, the required testing and measurement procedures are sometimes unpractical, costly and not indicative of operating conditions. This chapter considers the alternative of online monitoring by means of which more continuous assessment is possible under operating conditions. Some of the developments during the past decade are discussed, including a number of new techniques aimed at overcoming many difficulties in implementing in-service measurements. The cost, reliability and convenience of the new systems need to be balanced against the savings effected by reduction in outages and the extension of life of the insulating materials.

Inspec keywords: insulating materials; condition monitoring

Other keywords: insulating materials; online insulation condition monitoring techniques

Subjects: Insulation and insulating coatings