HT cables with thick crosslinked polyethylene insulation - by passing the extrusion coated cable down tube filled with heat transfer fluid under pressure to prevent distortion of the covering

摘要

High tension cables with thick cross-linked polyethylene insulation are made by applying the insulation to the conductor using an extruded, and subsequently crosslinking the material by passing the cable in the form of a free hanging catenary down a tube contg. a heat exchange fluid under press. to prevent the insulation dropping off the conductor during the crosslinking stage. Suitable heat exchange fluids are e.g. water at 180-115 degrees C, aliphatic OH-contg. hydrocarbon or aq. solns. of these, polyhydric alcohols and acids or their mono-, di- or triesters, esp. (di)ethylene glycol or triethylene glycol. The pressurised heat transfer fluid increases the dimensional stability of thick extruded coverings of crosslinkable polyethylene in the period just after extrusion, and allows the crosslinking to take place without distortion of the covering.