cable for power inattaccabilr by so-called trees water and manufacture of the same

摘要

In the case of heavy-current cables for relatively high voltages, there is a risk of so-called water trees forming in the plastic insulation. In order to avoid this, after manufacturing a cable having a conventional construction, namely a core (1), a first semiconductive layer (2), a polymer insulation (3) and a second semiconductive layer (4), a layer (5) having an active material is applied, which is covered by a covering layer (6) consisting of polymer material. The active layer has a content of 0.01-0.1 g of active material per cm2 of layer surface. Water-soluble salts, salt-forming stable hydrates, or acidic and basic anhydrides, for example, are suitable as the active material. These materials have the property that they limit the relative humidity in their vicinity to a value below 70%, that is to say to a value at which water trees virtually no longer occur. In consequence, it is possible to dispense with watertight but expensive metallic cable sheaths. IMAGE