The invention relates to a
direct current cable for subway, which comprises a conductor, wherein the conductor adopts
tin-plating
copper wires; the strand is stranded by a plurality of
tin-plating
copper wires; water blocking yarns are clamped among the
tin-plating
copper wires; a power wire core is stranded by a plurality of strands horizontally coated with double-surface semi-conductive water blocking tapes and is coated with two
layers of double-surface semi-conductive water blocking tapes outside which
polyester film tapes are coated; the
polyester film tapes is coated with 105 DEG C heat-resistant, high-strength and
flame-retardant
ethylene propylene terpolymer rubber outside which an expansion type semi-conductive
water resistance tape is coated; aluminum plastic composite tapes are arranged outside the expansion type semi-conductive
water resistance tapes and are overlapped, horizontally coated and welded in a lapping way; a high
flame retardant
oxygen-
blocking layer is extruded and coated between the aluminum plastic composite tapes and a
polyethylene inner sheath, wherein the high
flame retardant
oxygen-
blocking layer is filled with a great amount of organic flame retardants, such as
metal hydroxides of aluminum
hydroxide,
magnesium hydroxide and the like; a ratproof, termiteproof,
ultraviolet-resistant, low-
smoke,
halogen-free and high flame retardant type polyolefine sheath is arranged outside the
polyethylene inner sheath. The invention can be completely used under bad geological conditions.