GB329638A - Improvements in or relating to containers, for example, containers enclosing electrically fusible elements, liable to be subjected to relatively large internal fluid pressures - Google Patents

Abstract

329,638. Cruttwell C. E. Nov. 21, 1928. Fusible cut-outs.-A container for a fusible cutout comprises a fluid-tight inner chamber having walls which are electrically non-conducting and heat resistant, and an outer internal-pressure-resisting metal casing hermetically enclosing the inner chamber, the space between the chamber and outer casing being filled with oil or other liquid. The walls of the inner chamber are sufficiently flexible to transmit pressure through tne liquid. Provision is, also made for taking up the pressure due to liquid expansion with temperature increase. In one construction, Fig. 1, the inner chamber, which may be elliptical in section, comprises a corrugated tubular member 12 provided with flanges 20 secured in the sleeves 14 by plugs 18 and discs 16. Connection caps 22 provided with slits 24 are located in metal end-plates 30 by insulating sleeves 36. The outer casing comprises a steel cylinder 26 lined with insulation 28 and is provided with a plunger 40 operating a signal when the fuse blows. The slits 24 cause a throttling of the oil located between the fuse chamber 10 and casing 26 and prevent endwise fracture. In a modification, a diaphragm is mounted in the connection cap at one end, the inner side of the diaphragm being in direct communication with the fuse chamber. A smaller volume of oil is employed and it is confined to a tortuous passage. In a further modification, a double diaphragm is located centrally of the fuse element which has a central portion of restricted cross-section, thus localizing the first effects of an explosion. In other constructions, the diaphragms are replaced by spring pistons within cylinders. Another construction, Fig. 6, comprises the addition of a spring-loaded ram 66 which exerts a pressure on the oil filling in a direction counter to that caused by the explosion. In a further construction, Fig. 8, an oil reservoir 102 is mounted in the casing 26 and is provided with a capillary passage 106 which permits changes of oil volume with temperature. The cover 108 hermetically seals the reservoir and maintains' the oil under high pressure. In modifications, the chamber 10 may be corrugated and the oil reservoir open to the atmosphere. Porous plugs may be employed instead of the capillary passages. Gas pressure may be maintained above the liquid by an auxiliary supply of air or gas at high pressure. According to the first Provisional Specification, calcium carbonate may be enclosed within the casing, the carbon dioxide liberated under heat assisting to extinguish the arc.