Bazutkin - Moscow Power Engineering Institute Moscow, Russia
Litvinov - Moscow Power Engineering Institute Moscow, Russia
Qiwen Lin - Moscow Power Engineering Institute Moscow, Russia

Vacuum switches are widely applied to the distribution system of modern industries owing to their compactness and higher capability of many switching operations with reduced maintenace. From this viewpoint, vacuum switches can be effectively used to control high-voltage motors, furnace transformers and other large electric loads. Vacuum switches have some obvious advantages as compared with the older equipments. Small size and reduced weight make for more efficient space utilization. The small weight of moving parts, short contact stroke and minimal contact erosion permit a fast interruption and long working life. Fast recovery of the dielectric strength of vacuum interrupters contributes to the excellent and reliable interruption performance of vacuum circuit breakers. The arcing takes place in hermetically sealed vacuum inter rupters, so that vacuum circuit breakers are relatively noise-free, with no explosion hazard. The excellent interruption and dielectric recovery characteristics of vacuum interrupters, at the other hand, contribute to their current chopping and multiple properties, accompanying with high-frequency overvoltage /1-2/. Therefore it is a pressing problem to limit overvoltages with installation of Nonlinears Resistors, surge capacitors and capacitor-resistor (C-R) suppressors /3-5/. The Nonlinear Resis tors only suppress magnitudes of overvoltage, but don't eliminate the reignitions. The installation of surge capacitors can reduce the natural frequency of the load circuit, limit the steepness of overvoltage. C-R suppressors can eliminate the reignitions owing to the decreasing of the rateof-rise of transient recovery voltage. The paper relates the problem of the limitation of overvoltage caused by operations of vacuum circuit breakers at power supply of power stations by means of optimal parameter selection of C-R supressors. The numerical method, which was built on the basis of operative method and specially developped for calculation of highfrenqucy overvoltages, was used for numerical calculation of processes at the circuits.