Device for detecting interfering arcs

A device for extinguishing interfering arcs in a normally darkened internal space containing a high-voltage circuit breaker, comprising:

• light detector means for detecting light pulses resulting from electrical arcs in said internal space and producing an output digital signal having an amplitude and a duration representative of the respective amplitude and duration of said light pulses;
• a threshold detector which is operatively coupled with said light detector means and which produces an indicator signal whenever the amplitude of said light detector means output signal is above a predetermined threshold amplitude level, the duration of said indicator signal being equal to the time period during which the amplitude of said output signal is above said predetermined threshold amplitude level;
• timing means operatively coupled with said threshold detector for monitoring said indicator signal and, when the duration of said indicator signal exceeds a predetermined threshold duration value thereby indicating an interfering arc, generating a control signal;
• and
• means responsive to said control signal for extinguishing said interfering arc.

A device for extinguishing interfering arcs in a normally darkened internal space containing a high-voltage grounding switch, comprising:

• light detector means for detecting light pulses resulting from electrical arcs in said internal space and producing an output digital signal having an amplitude and a duration representative of the respective amplitude and duration of said light pulses;
• a first threshold detector which is operatively coupled with said light detector means and which produces a first indicator signal whenever a rate of increase of the amplitude of said light detector means output signal is above a predetermined threshold level;
• a second threshold detector which is operatively coupled with said light detector means and which produces a second indicator signal whenever the amplitude of said light detector means output signal is above a predetermined threshold amplitude level, the duration of said second indicator signal being equal to the time period during which the amplitude of said output signal is above said predetermined threshold amplitude level;
• a coincidence circuit having a first input terminal operatively coupled with said first threshold detector and a second input terminal operatively coupled with said second threshold detector, said coincidence circuit producing a coincidence signal when said first indicator signal is being produced as said second threshold detector begins producing said second indicator signal, the duration of said coincidence signal being equal to the duration of said second indicator signal;
• timing means operatively coupled with said coincidence circuit for monitoring said coincidence signal and, when the duration of said coincidence signal exceeds a predetermined threshold duration value thereby indicating an interfering arc, generating a control signal;
• and
• means responsive to said control signal for extinguishing said interfering arc.