Electric cables, fire-resistant, MAINLY explosion and fire, propagating burning, for intrinsically safe circuits

摘要

The invention relates to fire resistant structures multiconductor electrical cables, flame-retardant, intended for fixed mounting of electrical devices interinstrument industry, including in explosive zones of all classes of protection by using different methods, including the "intrinsically safe circuit i». The cable comprises a core consisting of at least one isolated conductive solid or stranded copper or tinned copper wires, or at least one group of said conductors, a twisted pair or three or four. Fire-resistant core made from a two-layer combined insulation, a first layer adjacent the current-carrying conductor is formed by extruded silicone rubber keramiziruyuscheysya under the action of the flame, the second layer is made of at least one slyudinitovoy ribbon superimposed winding helically overlapping mica coated inside with a tension belt winding at least 7 H. in order to identify the top winding slyudinitovoy ribbon on each insulated conductor is applied a contrasting ink or paint individual prefecture ep. Superimposed over the core shroud at least one slyudinitovoy ribbon winding helically overlapping mica coated inside. Cores or group with the number more than one can be twisted into the core. The cables can have individual screens, superimposed on a single core, the group screens, superimposed on these groups, the overall screen - superimposed on top of the core shroud of slyudinitovoy tape. Screens may be in the form of a braid or coil of copper or tinned copper wires, in the form of a metal-winding wire ribbon with a screen, or a combination - of the braid or winding podpuschennoy beneath upwardly metallopolymer metal tape. Over the cable core can be superimposed concentric layer polymeric filler. The filler may be further inserted into the air core and cavity of said groups, to provide a partial longitudinal sealing. the filler material may be foamed. Under moisture proof wrapper can be further routed armor in the form of a braid or winding of round steel wires, in the form of winding steel strips longitudinally from the pre corrugated steel tape laminated polymer. Waterproofing and casing must be made extruded way of one of the following materials: special PVC compound with oxygen index of not less than 35 with reduced dymogazovydeleniem or halogen-free polymer composition with an oxygen index of not less than 35, or a polyolefin thermoplastic elastomer with oxygen index of not less than 29, or a polyurethane thermoplastic elastomer with an oxygen index of not less than 29, or a silicone rubber with an oxygen index of at least 29, including keramizir uyuscheysya under fire conditions. The technical result consists in ensuring operability of the proposed cable during a fire at a temperature not lower than 830 ° C with mechanical impacts to the base of the cable attachment with the periodicity of one shot every five minutes during 180 minutes followed by gradual pouring of the middle portion of cable 400 mm long, to visit fire, water in a volume of 5 liters. Cables of this utility model may be used to connect the smart sensors and actuators located in various hazardous areas for systems providing performance during fire at a temperature not less than 830 ° C under the influence of fire extinguishing means in the form of mechanical shocks and exposure to water, thus more effectively fight fires at oil and gas enterprises.