| The paper states an overview of the present research status of switching overvoltage of vacuum circuit breaker both home and abroad, analyzing the mechanism of overvoltage in switching off shunt reactor and capacitor. When a vacuum circuit breaker switchs off inductive or capacitive load,due to chopping current or restriking,sometimes overvoltage will be generated and do harm to the insulation of the equipments. In the field test, switching off 35kV shunt reactor and capacitor is conducted, and vacuum interrupter is changed. Suppression measures are taken to carry out the operability test, using normal metal-oxide surge arrester, the combined metal oxide surge arrester with series gap and without series gap, RC absorbers, etc. respectively. The field overvoltage data are achieved and different effects of the protections are analyzed according to the data, thus the best protection program has been achieved: A group of RC is installed on 35kV bus, a group of RC is installed on shunt reactor, and a group of combined metal oxide surge arrester without series gap of HY5WZ-51/150*134 three-phase is installed on load-side of the circuit breaker. Field test study of the feasibility to the overvoltage protection programs of the vacuum circuit breaker switching off capacitor is stated in the paper. Experiments show this protection program (RC absorbers) can effectively suppress the overvoltage produced in switching off the capacitor. Finally the paper discusses the resin quality of several protection equipments and the problems that call for special attention in use. RC absorbers is comparatively better than others. The conclusion and analysis in the paper can provide protection schemes against overvoltage in switching off 35kV shunt reactor and capacitor, meanwhile providing reference for design and selection of overvoltage protection equipments. In the end, further researches on highly effective overvoltage protection devices are predicted in the paper. |
PDF Full Text Request