1. Electric heating material for heating cable

Heat tracing cable is an intelligent self-regulating electric tracing hot wire, and its heating element is a composite conductive polymer, which is formed by adding conductive materials (such as carbon black, stone black, carbon fiber, metal powder, etc.) as the substrate. It is a strip (linear, plate-shaped) device formed by a conductive polymer composite material with PTC effect squeezed between two parallel conductive cores.

The heating element is PTC material with positive temperature coefficient effect (PTC material for short), which forms PTC core belt through two wires and is equivalent to an infinite number of self-adjustable parallel resistance circuits. The so-called "PTC" effect refers to the phenomenon that the resistance of heating material increases with the increase of temperature. Therefore, it can automatically adjust the electrothermal output power with the change of temperature. When the temperature rises to a certain temperature, its resistance tends to infinity, that is, the output power is approximately zero, and vice versa.

The above phenomenon is referred to as the PTC product memory characteristics and switching characteristics (its substrate can be selected: fluororesin as the substrate or polyethylene as the substrate). Therefore, the electrothermal material belongs to composite conductive polymer with conductive filler (such as carbon black, etc.).

The quality of zhongrui automatic temperature tracing cable mainly refers to the stability of its memory characteristics and switching characteristics (switching points). When the product is at a critical high temperature point (zui high bearing temperature), its stability accumulatively decays until no heat is generated. In a certain condition (that is, refers to the level of the working voltage, the number of times of power on, the level of the internal and external ambient temperature when using, the level of the long-term operating state is the size of the output power, etc.), the more demanding the condition, the more stable the "memory" and "switch" characteristics, the better its quality. Therefore, to compare the merits and demerits of zhongrui automatic temperature-electric tracing cable, the application comparison should be made under the same use condition, or the severity degree of similar products' stability adaptability condition should be compared. The more demanding the adaptability condition is, the better its quality is.

2. PTC memory performance of automatic temperature tracing cable

The heating element of the automatic temperature tracing cable is made of polymer PTC material. In order to delay and prevent the harmful adhesion of conductive carbon black, zui can "fix" the distribution of carbon black particles in the polymer substrate, so that the core band can always "remember" the resistance at different temperatures.

That is to say, the change of the core resistance during each cooling process is always reversed along the PTC track of the resistance during the heating process, so that the core resistance has the PTC memory function. Therefore, products need radiation crosslinking. This not only improves the heat resistance of the core (such as short exposure temperature), but also extends the working life of the core. This kind of cross-linked automatic temperature tracing cable can still maintain excellent PTC performance and effectively prevent NTC effect after long time power tracing or repeated action of external cold and heat cycles.

3. Structure and working principle of self-regulating heat tracing cable

Zhongrui basic type automatic temperature tracing cable is composed of PTC core and insulation layer. PTC material thickness uniform, continuous extrusion (or winding) on the parallel metal core (also known as bus), made of the flat belt is PTC core belt. The basic type cable is made after the outer coating insulation layer. When the two conductive busbars at one end of the core band are connected with the power supply, the current will flow through the PTC material layer in parallel from one busbar to the other, forming a parallel circuit.

A certain length of core has a certain resistance at a certain temperature and has PTC characteristics. When the current flows through the PTC material layer in parallel, joule heat is generated and the core zone is heated. At the same time, the heat of the core belt is transferred to the heating system with low temperature through the cable insulation layer to compensate the heat lost from the system to the environment.

When the electric power of the cable is equal to the heat loss of the system, the system temperature can be kept stable, and the cable and the system can reach the stable working state (i.e. steady state) of thermal insulation. Therefore, the PTC material layer is the resistance heating element, and the PTC core belt is the heating element of the heating cable. This kind of long strip cable (electric tracing band) is an excellent thermal insulation equipment, in addition to the unique thermal tracing function, its long strip structure is convenient for tiling or winding installation of the complex insulation system.

According to the needs of industrial heat tracing and insulation, the basic type of cable can be made with additional shielding layer and sheath layer for different purposes. Zhongrui automatic temperature tracing cable has explosion-proof automatic temperature tracing cable and anti-corrosion automatic temperature tracing cable.