IMPROVING DIELECTRIC DISSIPATION FACTOR OF 420 kV CLASS OIL-SF6 RIP BUSHINGS AT SITE

Harish K. Sharma,∗ Savita Nema,∗ and Rajesh K. Nema∗

Keywords

Bushings, RBP, OIP, RIP, Tanδ, dielectric

Abstract

The resin-impregnated paper (RIP) bushing offers many benefits over the resin-bonded paper (RBP) or oil-impregnated paper (OIP) bushings. RIP bushing that is upgraded with a new generation of epoxy resin-impregnated crepe paper insulation, which is hygro- scopic in nature, is highly cured, dried, and processed during the production. The challenging job is to ensure the dried conditions during the long lead time of transportation, storage, erection, test- ing, and commissioning, though they are preserved and transported in a very protective environment. During the pre-installation check at various commissioning sites, the Tanδ value of RIP bushing must conform to the International Council on Large Electric Systems (CIGRE) standard, else it had to be replaced with a new healthy bushing, causing unnecessary delay in the project schedule and increase in the project cost. As on date, no such on-site Tanδ improvement procedure is reported/available in the literature that could improve Tanδ of the RIP bushing with the detrimental value. A new on-site dry-out procedure is evolved and discussed in this paper to improve Tanδ of the RIP bushing.

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