Innovative Three-Phase Ice Test of Diamond-Shaped “Suspension” Insulator Arrangement for T-Pylon Tower

摘要

The innovative three-phase full-scale tests for a 420 kV insulation structure were developed and performed in the following sequence: calibration,ice accretion,power frequency withstand voltage test,after-test measurements of ice conductivity and density.The specific representative test method was needed to provide ice accretion on a complicated geometrical insulation structure,which was then tested full-scale from three single phase test transformers.The glaze type of ice(clear transparent ice)was accreted on the de-energized insulator arrangement through spraying by water from approximately 1 m distance.The voltage withstand tests were performed in "melting regime" mode according to the principles of IEEE 1783.This simulates the "sun-rise" service case.This simulation was achieved by an increase of temperature in the climate test hall after finalization of ice accretion.The increase of temperature was obtained by letting in clean fog(steam)into the test hall with an additional flow of warm air from outside room through the small door to the test hall,while fans at the roof were slowly evacuating the air,creating a slight draft.All voltage withstand tests were performed at the test voltage of 243 kV.This voltage was maintained through the melting phase.The paper presents more details on each stage of testing philosophy and practical results for all three voltage applications.