PURPOSE: To protect a nonlinear resistor against thermal runaway or deterioration at a normal operating voltage.
CONSTITUTION: An overvoltage suppresser comprising a plurality of stacked zinc oxide elements 4a being jointed through fixing metals 5, 6 and a switching section 3 having female and male electrodes 7, 8, placed in a grounded metallic tank 9 while being connected in series, is further provided with means for suppressing the voltage to be born by a unit zinc oxide element 4a below a rife guarantee level. According to the constitution, the ratio of normal operating voltage to be born between the switching section and nonlinear resistor can be controlled. In case of a nonlinear resistor constituted of a zinc oxide element, voltage to be born by the nonlinear resistor can be suppressed below a voltage appearing when several mA of resistive component current is fed thereto.
Shoji Shindo
Kazuya Oishi
Ohno Masatomo
