Middleton, Robert

Chief of Technology and Engineering, RHM International, United States

Middleton, Robert

Chief of Technology and Engineering, RHM International, United States

Biography

Dry Type Paperless Bushings for T&D Power Systems

Mr. Middleton received a degree in Electrical Engineering from the University of Manitoba in 1971 and is a registered professional engineer in the Province of British Columbia. He has an extensive background in generation and transmission engineering including quality assurance and has served on several CSA, CIGRE and IEC Working Groups. Author of numerous technical papers, he is presently Chief of Technology and Engineering for RHM International, a manufacturer of high voltage dry type current transformers, bushings and cable terminations. Prior to joining RHM International he worked over 40 years at two Western Canadian provincial electric utilities.

Synopsis

Dry Type Paperless Bushings for T&D Power Systems

A transformer bushing functions to safely transfer power through the earthed transformer tank. Oil-impregnated and resin-impregnated paper type bushings have been the industry standard for decades and have generally performed satisfactorily. However, as transformer assets age, deterioration of the paper in originally supplied bushings can cause failure, sometimes even catastrophic. As a result, there is increasing movement these days toward silicone insulated, dry type, paperless condenser bushings that can offer improved safety, no risk of leaking oil, optional maintenance requirements and lower installation weight. Indeed, several suppliers now offer this new bushing technology, which is referred to as resin-impregnated synthetic (RIS) – the common generic terminology for dry, paperless bushings. Resin-impregnated fiberglass (RIF) is the registered trademark of a dry, paperless insulation style of bushing that broadly falls within the RIS category yet is itself a distinctive technology. Introduced in 2003 and with more than 22,000 units installed worldwide, it has greater service experience than the RIS bushing, first launched in 2014. This paper and presentation reviews differences between RIS and RIFtype bushings in terms of technology and also how the condenser core is manufactured.