Protective means for series capacitors
First Claim
1. A protective means for a series capacitor in a high-voltage network, said means comprisinga voltage-dependent resistor arranged in parallel with said capacitor,a spark gap arranged in parallel with said resistor for shunting the latter in case of overload thereof,a current-sensing member for sensing the current through said resistor,an energy absorption detector for sensing the temperature of said resistor, anda pulse transformer electrically or magnetically connected to said current-sensing member, for triggering said spark gap,said current-sensing member, during normal operation, being short-circuited by a switching device which is controlled by said detector in such a way that the switching device is opened if the temperature of said resistor exceeds a predetermined level, whereby a trigger pulse, generated directly by the resistor current via said current-sensing member and said pulse transformer, may pass to said spark gap.
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Abstract
A protective means for a series capacitor in a high-voltage network comprises a voltage-dependent resistor (varistor) arranged in parallel with the series capacitor, a spark gap arranged in parallel with the varistor for shunting the latter when it becomes overloaded, a current-sensing member, for example a current transformer, for sensing the current through the varistor, an energy absorption detector for sensing the temperature of the varistor, and a pulse transformer electrically or magnetically connected to the current-sensing member, for triggering the spark gap. During normal operation of the network and the series capacitor the current-sensing member is short-circuited by a normally closed switching device. This switching device is controlled by the energy absorption detector in such a way that the switching device is opened if the temperature of the varistor exceeds a predetermined level, whereby a trigger pulse, generated directly by the varistor current via the current-sensing member and the pulse transformer, may pass to the spark gap.
53 Citations
10 Claims
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1. A protective means for a series capacitor in a high-voltage network, said means comprising
a voltage-dependent resistor arranged in parallel with said capacitor, a spark gap arranged in parallel with said resistor for shunting the latter in case of overload thereof, a current-sensing member for sensing the current through said resistor, an energy absorption detector for sensing the temperature of said resistor, and a pulse transformer electrically or magnetically connected to said current-sensing member, for triggering said spark gap, said current-sensing member, during normal operation, being short-circuited by a switching device which is controlled by said detector in such a way that the switching device is opened if the temperature of said resistor exceeds a predetermined level, whereby a trigger pulse, generated directly by the resistor current via said current-sensing member and said pulse transformer, may pass to said spark gap.
Specification