Operation principle:
A heating cable with a constant output is basically a chain of equal rezistors R connected parallelly, which provides the same output for each one of these sections. These rezistors are made of a resistance wire wound around the insulated supply conductors, with which thye are conductably connected in every contact point.
The sections between 2 adjacent contact points are marked as moduls. Therefore, this cable can heat only in the space between the 2 contact points, as shown in the following picture:
Heating cables with a constant output are fitted with the following insulations:
FTP type - thermoplastic (PVC),
FTSH type - silicone rubber,
FTTH type - fluorinepolymer (Teflon).
The letter H in the type marking indicates the flicking of the contact points for reasons of a higher reliability at higher operation temperatures. The attributes of each cable are based on the used insulation material. PVC insulation is used for temperatures up to 90°C. Silicone and fluorinepolymer insulations are resistant to temperatures up to 200°C. The fluorinepolymer insulation also has an excellent mechanical resistance and resistance for chemical influences.
Heating cables with a constant output are characterized by a set output for a length unit [W/m]. Their length can be random an is only limited by the maximal current running through the supplying conductors. They can be shortened at installation as required without the need for any precise length calculations. They are powered from one side, the other side has a blind end. Specific accessories are used for the installation of each type of cable. The supply of these cables is initiated by a thermostat or regulator according to the pipe, technology or space temperature.
Heating cables with a constant output produced in several modifications. The principle of their marking is following:
FTx - basic version of the heating cable
FTx/T - heating cable with a tin-plated copper braiding, serving as a mechanical protection and grounding
FTx/I - heating cable with a stainless steel braiding, serving as a mechanical protection and grounding with an increased chemical resistance
FTx/TP - heating cable with a copper braiding and an outer thermoplastic jacket, which provides a mechanical and chemical protection against water-based compounds
FTx/TF - heating cable with a copper braiding and an outer fluorinepolymer jacket, which provides a mechanical and chemical protection against hydrocarbon-based compounds
FTx/IS - heating cable with a stainless steel braiding and an outer silicone jacket, which provides a mechanical and chemical protection against hydrocarbon-based compounds
In each series, there are several versions available with different nominal outputs.
Příklad značení topného kabelu:
FTSH/TF 30 - heating cable with a constant output with a silicone insulation, tin-plated copper braiding and an outer flurinepolymer jacket designated primarily for industrial applications. Heating output is 30W/m.
Standard supply voltage of heating cables with a constant output is 230 V, but can change up to 750V after an agreement.
