![]() ![]() ![]() With the decrease in power output as the cable temperature increases, it is not possible for the cable to affect an increase to a temperature beyond a certain level, regardless of the level of thermal insulation used.Ĭonstant wattage heat tracing cables do not vary its output depending on temperature and there are times where this is an advantage. This also gives rise to another highly desirable characteristic of self regulating cables, which is the ability to assign a T class (temperature rating) for ATEX purposes and safe installation in hazardous area locations. This is not to say it will hold a fixed target temperature without external control, but the reduction of output as the work-piece temperature increases is a desirable feature from an energy conservation perspective. Starting with the former, at higher temperatures the heating cable backs off its output, saving power even if not connected via a controller or thermostat. Self regulating heat tracing cables have an improved level of inherent efficiency as well as increased safety, if its application is correctly considered. This type of cable then has the feature of reducing its power output as temperature increases and conversely at lower temperatures, the power is increased.Įltherm Heating Cables – Self Limiting Heat Tracing Cables However, this resistance and therefore the output of the heating cable varies depending upon the temperature, due to microscopic expansion and contraction of the polymer. The live and neutral wires are co-extruded into a polymer based material containing particles of carbon, providing a resistance path and hence circuit along the length of the heating cable. Self regulating or self limiting heat tracing cables in effect also provide a controlled wattage per metre of cable but with a distinct difference, both in terms of construction and performance. This means pipes will not burst due to ice expansion. By maintaining the ambient temperature inside the pipe, frost cannot build up and pipes will not freeze. The first and most widely needed benefit of heat tracing systems is the prevention of freezing within pipes and with temperatures dropping daily, freezing pipes are now a major concern for homeowners, businesses and industry alike. Since each zone of heating is essentially in parallel with the zone before it, the supply voltage will remain constant along the length of the heating cable, aside from a small voltage drop brought about by the summation of the tiny resistances of the live and neutral wires as the cable gets longer and longer. In the case of constant wattage cables, a fixed resistance filament is then spiralled along the length of the cable and soldered alternately to the live and neutral wire in fixed distances creating what are referred to as heating zones.Įssentially, every zone is a fixed resistance circuit supplied by a fixed voltage, providing a constant wattage along its length. The heat load is then created by two different methods. Parallel heat tracing cables use two ‘normal’ copper conductor wires which run in parallel along the length of the wire and form the basis of live and neutral. Parallel heating cables are typically available in two distinct variants constant wattage and self regulating (also known as self limiting). ![]() ![]() However, there is also an alternative in the form of parallel heat tracing cables. There are many occasions where this approach is in fact still the best solution. In application, such a simplified solution presents certain complications in application.įor one thing, it results in the need to bring both ends of the wire together for connection to the electrical supply, which is not always practical when installing heating cables.Īdditionally, it requires the need for a high variety of different resistances to be available, in order to facilitate the design of different outputs at different lengths of heating cable. This can be achieved simply by connecting a voltage across a length of wire, which will then dissipate a fixed level of power, based on ohms law. In addition to frost protection, heat tracing cables provide heat maintenance and heat recovery in the process and hazardous area industries. A gallon of water, when frozen, will expand to a volume 9% greater than the original gallon. This means pipes will not burst due to ice expansion – in this article we discuss the pros and cons of 2 types of heating cables self-regulating and constant wattage.ĭid You Know…. With temperatures dropping during the Winter months, freezing pipes are always a major concern for homeowners, businesses and industry alike. The primary function of heat trace cable systems is the prevention of freezing within water pipes and subsequently bursting. ![]()
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