Importance

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Abstract

A self-current-limiting device and a method of making self-current-limiting devices. These devices typically comprise melt processable, self-temperature regulating, irradiation cross-linked, electrically semi-conductive polymeric compositions having positive temperature coefficients of electrical resistance. The semi-conductive compositions contain electrically conductive particles, such as carbon black, dispersed throughout the composition in an amount ranging from about 15% to about 20% of the total weight of the composition. Heating cables made in accordance with the invention comprise two or more elongate substantially parallel spaced-apart electrical conductors that are electrically inter-connected by extruded forms of the compositions. The method is characterized by an efficient three step process wherein the semi-conductive composition is extruded over the conductors, radiation cross-linked and annealed. The method of the invention does not require the application of a shape retaining jacket to the cable prior to annealing. Additionally, only one annealing step is utilized.

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First Claim