Heat-tracing cables are essential in industries where temperature maintenance and freeze protection are critical. These cables provide a reliable solution to prevent freezing and maintain consistent temperatures in various applications. However, there are different heat tracing cables available on the market. Each works differently, and the choice is influenced by its intended application. 

So how do you know which heat tracing cable is ideal for your system? Fret not. Let us explore and compare the three primary types of heat tracing cables: power-limiting, constant-wattage, and self-regulating cables. Understanding their differences can help you make an informed decision when choosing the correct heat-tracing cable for your specific needs.

Learn More: What You Need To Know About Heat Tracing

1. Power-Limiting Heating Cables

Power-limiting cables consist of a coiled resistor alloy heating element wrapped around two parallel conductors. The distance between conductor contact points forms the heating zone length. This parallel construction allows it to be cut to length and terminated on site.

As the name suggests, the cables are designed to limit the amount of power they consume based on the ambient temperature. When the temperature drops, the resistance of the heating element decreases, resulting in an increase in power output. Conversely, when the temperature rises, the resistance increases, generating a limitation of the power output. 

This feature allows the power-limiting cable to be overlapped once since the power output of the heating element is reduced at cross-over points. It also makes the cable more energy-efficient and can help prevent overheating.

2. Constant-Wattage Heating Cables

Constant-wattage heat tracing cables comprise multiple constant electric power zones, which are formed by wrapping a fine heating element around two insulated parallel bus wires. A notch is created in the insulation on the opposing sides of the conductors, and a small heating circuit is then produced by fusing the heating element to the exposed conductor wire. This setup is repeated throughout the entire cable, creating the power zones. There is also an inner jacket separating the grounding braid from the bus wires.

This cable is ideal for applications where specific heat output is required, as it provides a consistent and uniform heat output throughout their entire system. Since it has a constant power rating per unit length, the wattage remains identical regardless of the ambient temperature. But this feature also comes with a drawback, as constant-wattage cables are not as energy-efficient as the other two heat-tracing cables since the former consumes a fixed amount of power.

Nevertheless, there are additional advantages to using a constant-wattage cable. Its parallel circuitry allows users to cut it to length in the field. Another benefit is that users can join constant-wattage heating tapes using a trace heating junction box or a jointing kit. However, please note that constant-wattage cables should not be crossed over themselves. Doing so can lead to overheating and eventual burnout.

3. Self-Regulating Heating Cables

Self-regulating heating cables are the most forgiving of all existing heat-tracing technologies. These cables’ unique conductive polymer core allows them to adjust their heat output based on the ambient temperature. As the temperature surrounding the cable drops, the conductive core contracts on a microscopical level. This change decreases the electrical resistance and creates numerous electrical paths between the conductors, causing the current to flow along these paths and warm the core.

In contrast, the core expands when ambient temperature increases. As a result, electrical resistance increases, and the number of electrical paths decreases, thus lowering the heat output. This feature means that self-regulating heating cables can be overlapped several times without the risk of overheating and degradation, as the power output is reduced at high temperatures, making it an ideal choice for use in potentially hazardous environments. 

Like constant-wattage cables, self-regulating heating cables can be cut to length in the field. However, they may not be as reliable as the former. The latter has a specific maximum exposure temperature. So they may be damaged beyond repair if subjected to temperatures above their limit. Self-regulating cables are also subjected to high inrush currents upon starting up. So a higher rated contactor is needed than the other heat-tracing cables.

Each type of heat-tracing cable has its strengths and is suitable for different scenarios. As a result, choosing your ideal heat-tracing technology depends on various factors. If you are unsure where to begin, do not hesitate to approach our friendly staff at Supermec for assistance. We have a comprehensive range of Raychem heat-tracing cables available at affordable prices. So you are guaranteed to find one that matches your requirements. Contact us today to learn more about our products.