Transient voltage surge suppressor with i.sup.2 r/i.sub.2 t overcurrent

Abstract

A transient voltage surge suppressor comprises a first series circuit formed of a normally-off voltage surge-responsive gas discharge tube and a first voltage clamping device connected across input terminals to which a line voltage is applied. It also includes a second series circuit formed of a first electrical energy absorbing impedance element and a second voltage clamping device connected across the first voltage clamping element, thereby forming a voltage-clamping, voltage divider circuit which clamps the voltage across the first voltage clamping element at a voltage level reduced in comparison with that obtained by the first series circuit alone. When the gas discharge tube turns on, it places both voltage clamping devices in the circuit simultaneously, so that the let-through voltage appearing across output terminals can be reduced to the voltage clamped by the voltage-clamping, voltage divider circuit. An overcurrent protection device is coupled in circuit with the surge suppressor circuit to prevent damage to the surge suppressor that may be caused by excessive thermal energy buildup or by a large magnitude current spike capable of destroying one or more components of the suppressor and thereby preventing the suppressor from performing its intended function. The overcurrent protection device comprises a pair of series-connected switches, physically configured as alterable conductor portions, so that severing either of the conductor portions will effectively decouple the line terminals from the surge suppressor circuit.