Title :
Blow-open forces on double-break contacts
Author :
Shea, John J. ; DeVault, Birch ; Chien, Yun-Ko
Author_Institution :
Sci. & Technol. Center, Westinghouse Electr. Corp., Pittsburgh, PA, USA
Abstract :
Measurements were made on a double-break contact geometries, commonly used in power distribution devices, to determine contact dynamics under various short circuit fault conditions. These measurements lead to a modification to improve contact dynamics during a short circuit. The modification consisted of a guide-rod which prevented contact arm rotation during arcing. Contact dynamics depended on two blow-open forces, magnetic repulsion and gas pressure. Both forces were quantified for various double-break contact geometries along with arc voltage and contact travel. The gas pressure, created by arc radiation, was found to be a significant blow-open force. Measured blow-open forces were compared to a sealed piston model to obtain an empirical equation for blow-open forces. Contact performance was also determined with and without the guide-rod for a range of arc currents
Keywords :
circuit breakers; circuit-breaking arcs; contactors; electrical contacts; gas blast circuit breakers; short-circuit currents; air contactors; arc currents; arc voltage; blow-open forces; contact dynamics; contact geometries; contact travel; double-break contacts; gas pressure; guide-rod modification; magnetic repulsion; power distribution devices; sealed piston model; short circuit fault conditions; Circuits; Force measurement; Geometry; Low voltage; Magnetic forces; Magnetic separation; Motion pictures; Rough surfaces; Springs; Surface roughness;
Conference_Titel :
Electrical Contacts, 1993., Proceedings of the Thirty-Ninth IEEE Holm Conference on
Conference_Location :
Pittsburgh, PA
Print_ISBN :
0-7803-1270-8
DOI :
10.1109/HOLM.1993.489666
