Abstract: The method is used to produce a varistor which has a cylindrical resistance body (1) made from a material based on metal oxide, and two electrodes (2, 3) which are each arranged on one of two mutually parallel end faces of the cylindrical resistance body (1). In a first method step, a layer of electrode material is applied to both end faces, as far as their outer boundary (9), which is designed as a sharp edge. In a second method step, a circular ring (4), which is delimited by the outer boundary (9), runs to as far as the end face of the resistance body (1) and has a width of from approx. 10 to 500 &mgr;m, is removed from the electrode, or the resistance body (1) and electrode are beveled (5′) at the outer boundary. The method allows simple and economic manufacture of a varistor.

Abstract: The resistor is designed in the form of a column and has a cylindrical resistor body which is arranged between two planar electrodes, aligned parallel, and is made of a ceramic material. The resistor is preferably a varistor on a metal-oxide base, and is then used as a voltage-limiting element in an overvoltage suppressor. The strength of the ceramic material and the length of the resistor are chosen to be as great as possible. However, the length of the resistor is at most sufficiently large that damage to the ceramic resistor body caused by thermally produced pressure waves is avoided when the resistor is loaded in an electrical field of given magnitude with at least one highly energetic current pulse of defined amplitude, form and duration.

Abstract: The method is used to produce a varistor which has a cylindrical resistance body (1) made from a material based on metal oxide, and two electrodes (2, 3) which are each arranged on one of two mutually parallel end faces of the cylindrical resistance body (1). In a first method step, a layer of electrode material is applied to both end faces, as far as their outer boundary (9), which is designed as a sharp edge. In a -second method step, a circular ring (4), which is delimited by the outer boundary (9), runs to as far as the end face of the resistance body (1) and has a width of from approx. 10 to 500 &mgr;m, is removed from the electrode, or the resistance body (1) and electrode are beveled (5′) at the outer boundary. The method allows simple and economic manufacture of a varistor.

Abstract: A method for manufacturing a precursor powder for use in making a varistor is disclosed. This precursor powder is produced by preparing a homogeneous aqueous dispersion of metal oxides and/or metal hydroxides and heating the dispersion in a closed pressure reactor to a temperature between 200.degree. C. and 350.degree. C. for hydrothermally treating the homogeneous dispersion. The precursor powder produced in the afore-described method is highly homogeneous and of controlled crystal phase and morphology and after mixing with zinc oxide powder can homogeneously be reacted with the zinc oxide in a ceramic process.