Porcelain insulators for EHV outdoor cable terminations. Improvements in pollution performance

Privatisation of the UK Electricity Supply industry in 1990 prompted a review of specification and purchasing methods, resulting in a move to functional specification rather than detailed design specification. The examination of requirements revealed that different insulator types are used on cable terminations compared with other substation equipment, where the alternate long-short (ALS) shed insulator is prevalent. At the request of the NGC, cable termination designs have been examined with a view to bringing the insulator arrangement in-line. An industry project has been initiated to develop and test suitable designs to fully meet the new NGC specification, NGTS 3.5.6; 1994. “Outdoor Cable Sealing End Insulators”. This paper presents a summary of the development activity on this project, to date, from the cable termination manufacturers point of view. Discussion of the design, manufacturing and installation constraints, plus the early results of artificial pollution performance testing on prototype insulators are also included