Research on Sealing Performance of Valve Side Bushing of Converter Transformer under Large Load Current and Cantilever Load

Valve side bushing of converter transformer withstands large load current heating state during long time actual operation, and the terminal block at the top of the bushing withstands a certain cantilever load, which will directly affect the sealing performance. This paper aims at research on sealing performance of valve side bushing of converter transformer under large load current and cantilever load. A test platform for bushing sealing performance under cantilever load and large load current conditions is built. After the temperature rise current test in three stages is stable, cantilever load is applied to the top terminal of the bushing, and immediately measure the SF 6 gas concentration inside the leakage test chamber after applying the load. Under the superposition of large current and cantilever load, the bushing has no sealing damage or gas leakage rate exceeds IEC standards. Based on the test result of sealing performance under large load current and cantilever load, it can put forward the reliability evaluation method of converter transformer valve side bushing under long-term comprehensive state of temperature rise, mechanical and sealing performance.