Valve side lead exit insulation design used in ±800 UHV converter transformer

摘要

Valve side lead exit is a key important part of converter transformer, by which bushing terminal connects with the transformer valve winding. Valve side lead exit consists of bushing terminal and surrounding barrier system, and it is usually installed in the bushing ascending flange where resin impregnated paper (RIP), oil impregnated paper (OIP) and transformer oil co-exist in the compact place. So valve side lead exit insulation requires a focused analysis in the design stage. It not only withstands AC voltage, but also withstands DC voltage, polarity reversal voltage during factory testing and in operation. In this paper, to ensure insulation reliability of valve side lead exit, all resulting electric stresses, including electric strength in oil gap, in oil impregnated paper and along interfaces liquid/solid, had been calculated with the electric field program and compared to the industry accepted withstand curves. The result in this paper could promote independent design and complete localization of valve side lead exit used in ±800UHV converter transformer.