High-Frequency Current Interruption of Vacuum Interrupters in an Experimental DC Circuit Breaker

Abstract

Recently, several manufacturers have proposed and developed prototypes of high-voltage direct current (HVDC) circuit breakers (CBs) based on various dc current interruption principles. However, due to a lack of operational experience with this type of equipment, no clearly defined requirements that these new developments should satisfy exist. To define and refine justified test requirements, a thorough understanding of the interactions between the internal components of the HVDC CBs and the stresses on these components is necessary. For this purpose, an experimental dc CB based on the active current injection technique is setup in a high-power laboratory. The contribution of this paper focuses on the performance of vacuum interrupters (VIs) for dc CB application. The performances of three different VIs, designed for ac application, are investigated. About 200 tests, under different test conditions, have been conducted in which up to 850 current zero crossings (CZCs) are created. The test results are analyzed and presented in detail along with statistical information obtained from the analysis of the measured parameters. The test results serve to identify the critical stages of current interruption process that need to be demonstrated during typical current interruption tests of HVDC CBs. It is found that the three types of VIs behave very differently; the rate-of-change of current near CZCs is not the only key parameter; and successful current interruptions can still be achieved after re-ignitions and re-strikes.