Abstract: The present invention provides a voltage-dependent resistor of the bulk-type in which zinc oxide (ZnO) powder and additives are admixed to form a sintered body composition having as the main constituent, zinc oxide, and in which the mixture is formed into a resistor body, the body is sintered, and electrodes are applied to the opposite surfaces of the sintered body, the improvement comprising the step of, prior to sintering and admixture with said zinc oxide, admixing all amount of boron oxide (B.sub.2 O.sub.3) with other additives in the form of a borosilicate glass, which is composed of 5 to 30 weight percent of boron oxide (B.sub.2 O.sub.3) and 70 to 95 weight percent of silicon oxide (SiO.sub.2). A process for the production of said resistor is also provided.

Abstract: A voltage-dependent resistor having at least one zinc oxide (ZnO) layer adjacent to at least one metal oxide layer of bismuth oxide (Bi.sub.2 O.sub.3) and at least one of the members selected from the group consisting of cobalt oxide (Co.sub.2 O.sub.3) manganese oxide (MnO.sub.2) antimony oxide (Sb.sub.2 O.sub.3) and zinc oxide (ZnO).

Abstract: A voltage-dependent resistor of the layered structure type is provided by employing the nonohmic property of the hetero-junction between a zinc oxide layer and a metal oxide layer consisting essentially of at least one member selected from the group consisting of cobalt oxide, manganese oxide, barium oxide, strontium oxide, lead oxide and rare earth oxides.

Abstract: A voltage-dependent resistor comprising a sintered body comprising ZnO as a major part and additives wherein at least 10 weight percent of the ZnO is composed of ZnO grains having a grain size in the range from 100 to 500 microns; and method of making the same wherein the starting mixture comprises ZnO grains having a grain size in the range from 20 to 200 microns. This voltage-dependent resistor has both a low C-value and a high surge energy withstanding capability. It also has a low leakage current at a high temperature due to the addition of an antimony component as a spinel type polycrystalline Zn.sub.7/3 Sb.sub.2/3 O.sub.4.

Abstract: This invention provides a surge absorber for absorbing surges of electric current. The absorber has a metal oxide varistor hermetically sealed in a hollow insulator by a top and a lower electrical terminal and also has a conductive rod extending substantially downwardly and electrically connected to ground and to the lower electrical terminal by solder and also thermally connected to the metal oxide varistor whereby when the varistor is heated by a surge of an electric current therethrough to a temperature to heat the solder above the melting point of the solder, said conductive rod gets separated from the lower electrical terminal to fall downwardly, thereby stopping the electric current through the metal oxide varistor to ground.