29-03-2012, 02:58 PM
ELECTRICAL CABLE
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History of cable
History of Paper Insulated Power Cables
Early Cable Insulations
Unvulcanized natural rubber – 1811
Glass tubes – 1816
Gutta-percha – 1841 (Morse, NYC)
Vulcanized Natural Rubber – Goodyear patent
–1844 (telelgraph cable in 1860)
Parafined Jute & Vulcanized Bitumen – 1879
Natural rubber for power cables – 1880
Composition
Working voltage, determining the thickness of the insulation;
Current-carrying capacity, determining the cross-sectional size of the conductor(s);
Environmental conditions such as temperature, water, chemical or sunlight exposure, and mechanical impact, determining the form and composition of the outer cable jacket.
Belted cable
construction
core are insulated each othere by the layers of impregnated paper,
paper belt of impregnated paper tape wound around the grouped insulated core.
the gap between the insulated core is filled with fibrous insulaing material.
the belt is covered with lead sheath.