Abstract: A non-linear resistor assembly protecting equipment such as series capacitors is itself protected by a bypass spark gap, the firing of which is produced by a digitized pulse train, each pulse of which indicates a known increment of energy input to the varistors and is processed by counters and logic gates to achieve an initiating firing pulse upon the occurrence of a predetermined number of pulses indicating the energy input has reached predetermined limits within a given time period. The initial firing pulse is further processed through stages including semiconductor device switching, trigger spark gap firing and energy dumping from an energy storage capacitor into the elements of the main bypass spark gap.

Abstract: A multi-series group capacitor bank has voltage limiters, of the metal oxide type, connected across each individual series group and set at a protection level higher than that of the bank bypass spark gap so the voltage limiters bypass a series group when capacitor fuse clearing causes high voltage build-up in that series group.