Medium voltage fire-resistant electrical cable - has corrugated metallic sheath surrounding insulation layer to allow expansion of latter under effects of temp.

摘要

The electrical cable is made up of conductor (10) covered by an extruded layer of crosslinked polyethylene insulation (12) enclosed in a metallic sheath (18). The metallic sheath (18) is arranged around the insulation (12) so that an expansion space is formed between the outer surface of the insulation and the inner surface of the sheath. The insulation is thus free to expand under the effects of temp. The expansion space is formed because the metallic sheath (18) is in the shape of a longitudinal corrugated tube. Another form of sheath (18) has longitudinal corrugations as opposed to transverse corrugations. The interior spaces formed by the corrugations allow the insulation to expand. Between the insulation (12) and the metallic expansion sheat (15) is a semiconducting layer (14).