GB1443049A - Means for increasing the stability in high-voltage power supply networks - Google Patents

Abstract

1443049 Protective arrangements for capacitors ALLMANNA SVENSKA ELEKTRISKA AB 17 Dec 1973 [22 Dec 1972] 58361/73 Heading H2K To protect a capacitor in a high voltage power line from overvoltages, while retaining the effect of the capacitor, a current path is arranged in parallel with the capacitor 2 and its safety circuit, this current path comprising spark gap 4 in series with a voltage dependent resistor 3 whose resistance is very high as long as the voltage across the capacitor is below a predetermined value, higher than the capacitor operating voltage but lower than the voltage at which the safety circuit short circuits the capacitor, but whose resistance decreases as the voltage increases above this predetermined value. Where the spark gap is of the non-selfextinguishing type it is connected in parallel with a circuit breaker, Fig. 3 not shown. The safety circuit is of known type and comprises a circuit breaker which short circuits the capacitor when its contacts are closed. A second current path may be connected in parallel to the first and comprises an inductance 8 and a circuit breaker 6, the inductance and the voltage dependent resistor being connected in parallel by a spark gap 9 between the two current paths, Fig. 4. The voltage dependent resistor may be divided into two parts, only one of these parts being in parallel with the inductance Fig. 5 not shown. In a further embodiment a circuit breaker forming the second current path has an auxiliary contact which operates instantaneously and a main contact which has delayed operation. Fig. 6 not shown, so that part of the capacitor energy is able to be discharged through part of the voltage dependent resistor before the main contact is closed.