PVC Cables vs XLPE Cables

About these two insulation materials one could discuss a lot. I'll try to expose the essential, may be.

First of all PVC compounds it is not a "pure" material. PVC resin it is only about 40% in the compound and the remaining 60% is calcium carbonate as filling and also there are other materials as lubricants and stabilizers.

There are thousands combinations starting with the PVC polymer and other.

In my opinion PVC insulation material is cheaper.

Usual PVC is rated 70oC but it could be 105oC for some compounds.

Since the permittivity and tangent delta [dielectric losses] are elevated the rated voltage is limited.

In case of short-circuit-for short-time duration-a maximum permissible temperature of conductor is only 160oC.

PVC material it is a hygroscopic material-that means the water fills or penetrates the insulation decreasing so the electrical properties and increase the capacity.

PVC it is a fire retarding material itself, but in a case of fire the smoke contains chlorine which produces rapid corrosion of metals-even the reinforced concrete.

The materials halogen free are preferred. Halogens are elements as chlorine, fluorine, brome and iodine.

The smoke produced when these materials burn is stuffing and highly corrosive.

Polyethylene is halogen free but it is not fire retardant material .Cross-linked polyethylene is better. There are problem with water trees-phenomenon in which the water could penetrate into the insulation and break it out.

The TR XLPE-tree resistant crosslink polyethylene could overcome this phenomenon.

XLPE withstand 90oC steady and 250oC at short-circuit .Since dielectric factor [permittivity] is low, and the dielectric losses are also reduced the very high voltage cable could be produced with this insulation.