Constant Wattage cable

Typical Characteristics of product range

Available for hazardous area applications – Zone 1 & 2

Maximum Application Temperature to 425C

Maximum Circuit length – 200m

Cut to Length

Cable cannot be crossed on itself without potential over temperature damage.

These types of cables differ in the construction to self-regulating cables and in operation.

 In this construction the two bus-wires are extruded with an insulating layer over each conductor.

At pre-determined distances, the insulation is removed from alternate conductors, exposing the base conductor. A heating wire (or element) is wrapped around the two conductors, and where the wire meets these two areas, a heating ‘zone’ is created.

A layer of insulation is then extruded over the cable. Similar to the self-regulating cable, a further optional layer of metallic braid and a final thermoplastic or fluoropolymer insulation can be extruded over the cable to provide a finished product.

The heating element used has a very low alpha coefficient. This means that the resistance of the element is very uniform regardless of the temperature.

The advantages of constant output cables are that start-up currents are negligible.

A disadvantage is that the cable must not be crossed upon itself as hot spots may occur.