Patent ID: 6342828
Filing Date: 2002-01-29
Classification: H01C,Y10T

Abstract:
A method for producing a varistor which can be loaded with at least one highly energetic current pulse of defined amplitude, form and duration in an electrical field of a given magnitude, the varistor having a cylindrical resistor body with a defined diameter, made of a ceramic material and arranged between two parallel planar electrodes defining the length of the varistor, in which the ceramic material is formed in a sintering process from a prefabricated pressed body, the method comprising:determining a characteristic graph for varistors made of the same material and with the same diameters, but with different lengths, in which graph the mechanical stress produced in the ceramic material by loading it with at least one highly energetic current pulse is specified as a function of the length of the varistors, and in which a given electrical field strength and at least one current pulse of defined amplitude, form and duration are assigned as electrical parameters to each characteristic; loading sample varistors designed and dimensioned in a corresponding manner to the varistors on the characteristic graph, with the electrical parameters assigned to a characteristic, after loading the sample varistors with the electrical parameters, analyzing the sample varistors for their re-usability, determining from the analyzed sample varistors an upper limit length at which damage to the ceramic varistor body is still avoided, and designing the length of the varistor to be produced smaller than the upper limit length.