Resistor element for current limiting purposes especially during short-circuits

摘要

A resistor comprises a polymer matrix containing a low resistivity first filler and a second filler with a resistivity which decreases with increasing field strength and which has a specified maximum value at high field strengths. An electric resistor element with a resistive body of a polymer matrix, a first filler powder with a resistivity of /}10<-3> OMICRON .cm and a second filler powder with a resistivity which decreases with increasing field strength and which has a value of /}50 OMICRON .cm at field strengths of /-2000 V/cm. Preferred Features: The second filler has a resistivity of /-10<-2> OMICRON .cm and an average particle size greater than that of the first filler, the quotient of the average particle size of the first filler and that of the second filler being 2-5. The first filler consists of TiB2, TiC, VC, WC or ZrB2 of 10-40 mu m particle size and the second filler consists of doped SiC or doped ZnO of 50-200 mu m particle size. The resistive body contains 30-70 vol.% first filler and 10-40 vol.% second filler.