Self-current-limiting devices and method of making same
US5057673A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1988 |
| Grant date | Oct 15, 1991 |
| Priority date | — |
| Expiry date | May 19, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49083
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.