LIMITATIONS OF HIGH-POWER TESTING METHODS FOR EHV AND UHV CIRCUIT-BREAKERS

摘要

Over the last decades, tremendous developments in circuit-rnbreaker technology have resulted in designs thatrnare far simpler, more compact, more cost-effective, morernreliable and intended for low maintenance. The designsrnshow less interrupting units per circuit-breaker,rnand there is a trend towards more metal-enclosed circuit-rnbreakers and even three-phase enclosed GIS circuit-rnbreakers for higher voltage classes. The reductionrnin the number of interrupting units per pole can bernshown by examples such as a single arcing chamber forrn550 kV GIS circuit-breakers and a double chamber forrn800 kV and above.rnThe high-power testing methods and procedures have tornbe adapted in order to cope with the designs that showrnhigher stresses and, partially, other stresses, for instancernbetween phases (three-phase enclosed) or betweenrnlife parts and enclosure (metal enclosed, contaminatedrnwith exhaust gases). The test circuits and testing circumstancesrnhave to be adequate to properly representrnthose stresses. Apart from the importance of the dielectric,rnmechanical, gas dynamic and electrodynamicrnstresses inside the circuit-breaker, also the interactionrnbetween circuit-breaker and test environment has to bernconsidered carefully, taking in mind especially the arc–rncircuit interaction, the phenomena after a restrike andrnthe geometrical connections between critical elements.rnThe testing possibilities for EHV and UHV GIS circuitbreakersrnat High-Power Laboratories are illustratedrnand their testing policy is outlined. The limitations ofrnsynthetic testing and unit testing are given.