The recent developments of aluminium conductors in France in public distribution and industrial plants

Abstract

The use of aluminium for electrical conductors increases in parallel with electric power consumption in France; in other words, it doubles every ten years. Presently, this application is the second in importance, after transport and before packaging, machinery and architecture. Inspite of economic savings, the development of aluminium was difficult because of old customs in a field where copper enjoys a very long experience. This is the reason why we called for new solutions bringing on technical improvements and/or additional economic advantages. In the very high voltage transmission systems, the all-almelec conductors became serious competitors to steel-cored aluminium conductors. In the overhead distribution systems, in addition to the almelec conductors already used for 20 kV medium voltage, the pre-assembled insulated cables are now widening their acceptance, opening the way to aluminium access in the low voltage field which, until now, was almost prohibited to the light metal. First used for its screening properties in signal and telecommunication cables, aluminium sheath also offers an interesting alternative for underground cables, mostly for low voltage where it is used as neutral conductor. In the works' equipment, aluminium penetration becomes more important every day, owing to new simple and safe jointing devices, mostly for insulated cables. Busbars obtained by continuous casting directly from the furnace represent a valuable investment and are now used for feeding many furnaces, electrolysis cells, etc. Since many years aluminium is also used in generator-transformer isolated phase busbars, tubular conductors in outdoor substations, prefabricated low voltage ducting systems where the most recent technological improvement is the general use of light alloy bolts and nuts, replacing zinc or cadium-plated steel. Important research work is now in progress to introduce aluminium strip into windings for transformers and electrical machines in general. The recent achievement of a cryogenic transformer might prove to be attractive for the future very large sets. Finally, some electric heating devices are presently investigated: infra-red radiation panels, floor storage warming, both methods involving either aluminium foil or Properzi wire. The use of insulated wire is also considered for greenhouse culture heating. (Mr. Pierre Jacomet, Chief Engineer, Head of the Electrical Division, Aluminium francais, France)