Development of large-capacity VBO-free light-triggered thyristors and their application to SVC valves

Six kV 2500 A and 1500 A light-triggered thyristors with an overvoltage protection function or VBO-free LTT thyristors were developed. Using these thyristors, 100 MVA-class SVC valves were manufactured and subjected to one year of field testing. Features, structures and electrical characteristics of the developed large-capacity VBO-free LTTs are described. Specifications and construction of the SVC valve used in the field verification tests are introduced and field test results are given