Self-regulating cable - “smart” technologies at the service of humans

The demand for self-regulating heating cables in households and industry is growing every year. The arrival of the first autumn frosts, the sudden onset of sub-zero temperatures outside very often comes as a surprise to the owners of private houses and the management of administrative and industrial buildings. There is a risk of freezing and rupture of water and sewer pipes, icing of steps, and icicles forming on the roof, which break off and cause damage. In this situation, a self-regulating heating cable becomes a universal and effective solution to combat anti-icing.

General characteristics and differences of a self-regulating cable

Self-regulating heating cables are a whole line of heating cables and tapes developed using semiconductor nanotechnology, the distinctive feature of which is the independent change in power in different sections of the same section depending on the ambient temperature. They are popular when installing anti-icing systems, heating household pipes, as well as oil and gas pipelines.

Heating cables for anti-icing systems must meet strict criteria for reliability and service life. In practice, two types of electrical cables are most often used as such connections: resistive and self-regulating.

Resistive cables with constant power are a sealed copper core that has resistance to the entire circuit to direct current (the so-called ohmic resistance) and is covered with a special protective sheath. This core simultaneously plays the role of an incandescent element. Such connections have a specific extent, and their ability to release thermal energy is in no way related to air temperature.

For self-regulating cables, the heating element is a conductive matrix based on a carbon polymer, which can change such a characteristic as conductivity depending on the ambient temperature. The cable releases optimal heating power precisely where and when it is needed. As the ambient temperature drops, more heat is released. Conversely, as the temperature rises, less heat is released.

There are no disadvantages associated with an excessive increase in temperature or, conversely, with a lack of it. In addition, due to the presence of an automatic control device, large energy savings are created. In particular, ice protection systems using resistive connections (constant in power) consume twice as much energy as the same structures using a self-regulating type of connection. In addition, automatic heating systems provide maximum safety, and for extreme and difficult conditions of use, special types of electrical connections are made in accordance with the standards of the American Institute of Electrical and Electronics Engineers and the European Committee for Electrotechnical Standardization.

Such a heating system is much more advanced and safe than a resistive one and is capable of providing the most optimal heating mode even without additional automation. Its installation is more convenient since the cable can be cut at the installation site to exactly the length needed for specific purposes.

Introduction

Currently, industrial electric heating systems have become widespread for heating process facilities in the oil and gas industry. Many specialists of various specialties are involved in the implementation and subsequent operation of these systems, but this issue is not sufficiently covered in the technical literature, to put it mildly.

In this article we will not try to cover all types of heating elements used to build electric heating systems, but will focus on the features of the use of self-regulating heating cables (tapes), as the most rapidly developing and currently popular sources of thermal energy. All available information about self-regulating heating cables is often obtained by specialists from design and operating organizations only from manufacturers of this type of cable, who unanimously say: “Our products are of excellent quality and are practically free of drawbacks, with the possible exception of a slightly high cost in relation to other types of heating elements! Let's try to figure out whether this is really so, and what disadvantages are inherent in self-regulating heating cables.

Considering the importance of the operation of electrical heating systems of industrial facilities in the overall infrastructure of the enterprise, the question of understanding the main technical features of the use and operation of self-regulating heating cables will allow responsible operation specialists and design organizations:

• As a result of design and construction, obtain a technically sound, safe and uninterruptedly operating electric heating system.
• Reduce the cost of purchasing cables and auxiliary products.
• Reduce costs for subsequent operation of the system.
• Reduce energy costs as part of the facility's energy conservation program.

Operating principle and design

Self-regulating tapes and cables change power and heat generation, taking into account the temperature of the atmosphere, i.e. they constantly sense temperature changes without any additional sensors. As a result, different junctions between the cable and the heated object may have different temperatures, and devices and mechanisms adjacent to the connection will increase their temperature to varying degrees.

To supply voltage along the entire length of the self-regulating tapes without intersecting, a pair of stranded copper conductors is built in. They are supplied with constant electrical voltage. Between the electrical conductors is placed the key element of the cable - a specially manufactured semiconductor carbon polymer matrix designated PTC (Positive Temperature Coefficient). The meaning of the PTC effect is that the carbon nanomaterial that makes up the matrix, upon reaching a threshold value, changes its resistance and releases less power. Each manufacturer of a self-regulating cable has its own unique secret technology or recipe for producing a matrix (like every baker’s recipe for making bread). Moreover, the recipe for the soot from which the matrix is ​​made differs for types of samreg that differ in power and purpose. During the production process, carbon black undergoes a cross-linking process by irradiation with an electron particle accelerator. This is necessary to help the matrix maintain PTC characteristics and polymer stability during repeated heating and cooling.

It is also known that in the matrix structure, in addition to graphite particles, small metal nanoparticles are added to conduct current within the entire structure. The heated matrix expands, and the conductive metal-graphite bridges break. As a result, the resistance of the section increases, the current decreases, and heat generation decreases. When cooling, the reverse process occurs: the matrix shrinks, the number of communication channels between conductive metal nanoparticles becomes larger, the resistance of the power section decreases, power and heat generation increase.

Protective internal insulation made of Polyolefin or Fluoropolymer protects the matrix from wear and moisture, and an additional metal braid provides the function of mechanical protection and grounding at the same time. The outer sheath of the cable is also coated with Polyolefin or Fluoropolymer. If necessary, UV-resistant elements are added to the sheath if the cable is intended to be placed in open sunlight.

When a self-regulating electrical cable is connected to the network, the matrix begins to heat up along its entire length. Then, depending on the amount of heating, equilibrium occurs, i.e. Different connection points will release different amounts of thermal energy.

Let's sum it up

The uniqueness of the Heatus technical solution lies in the guaranteed savings for the end consumer. Savings at the time of purchase, as well as optimization of operating costs, is what everyone gets, regardless of their region of residence and their current needs. If we add to this the maximum set of kits, we get a budget, but at the same time effective, and durable solution, in which every millimeter of the heating cable works only when it is really needed.

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History of the invention of self-regulating cable

It is believed that the prototype of the self-regulating cable appeared in Norway during the Second World War. On September 16, 1940 (i.e., even before the outbreak of hostilities in this country), a patent was published in Oslo under number 747,883, the author of which was Peder Gunnar Sletner. However, due to the war and occupation, this patent was not considered. Its author was forced to emigrate to the United States, and only on May 14, 1947, he resubmitted his text to the US Patent and Trademark Office. The documents were carefully studied by the commission for more than two years. As a result, on January 17, 1950, this patent was officially published by the Office under the unique number US2494589 A.

According to the published text, an invention was patented representing a structure of two or more electrical conductors with opposite polarity (phase and neutral). Electricity conductors run parallel to each other without intersecting, but at the same time, they are connected to each other thanks to the nth number of contacts (resistors) parallel connected to them. Resistors are thin wire spirals made of high resistance metal. It should be noted that in the text of the patent there is currently no mention at all of the components (materials) of modern self-regulating systems - the polymer matrix. At that time, chemistry was not capable of synthesizing such complex materials. Instead, Peder Sletner offers us essentially the same resistive cable, with one unique property: it could be cut to any length without worrying about changes in its characteristics after cutting. Thus the zone cable was invented.

The Sletner cable has a significant advantage over resistive cables - if one resistor (connector of conductive cores) burns out, the system continues to operate in full mode. Only a small area of ​​it stops heating. This invention showed great promise for using such a cable in electrical heating systems.

After Sletner's patent, a series of patents began to improve his invention. In particular, patents 3757086 and 4037083 proposed various options for resistor alloys (nichrome, fechral) to increase the power output and efficiency of the heating cable. But this did not solve the issue of self-regulation of the system.

The technology of parallel connection of heating cables, which allows cutting and coupling heating cables of any length, began to be used for commercial purposes since 1971. This technology was purchased and used for commercial purposes by the American company Raichem, currently the world leader in the production of heating cables.

Further, over the course of almost 20 years, a whole series of patents followed, mostly from American authors, who began to propose solutions that allowed the zonal cable to emit temperatures that differed in different sections of the same section.

For the first time, the solution to the issue of autonomous cable temperature control was announced in patent US4250400 A dated February 10, 1981. It proposed connecting a small tablet-shaped thermostat in the middle of spiral resistors (high-resistance wires). This disk temperature sensor protruded beyond the cable and had to be in contact with the heated surface. As the surface temperature increased, the resistance of the temperature sensor increased, which reduced the linearly flowing electric current. As a result, the cable power dropped. Thus, the first self-regulating cable in history appeared. The diagram below shows a schematic diagram of this invention.

And only, 10 years later, on June 16, 1992. patent US5122641 authored by Robert M. DeChurch appears, in which the polymer matrix is ​​clearly beginning to be discussed as a cable heating element. The patent does not say anything about the composition of the polymer, only that it could be “various materials”, such as graphite or coal shavings. But the patented invention already contains indicative drawings of the technological process for producing the polymer matrix.

In the early 90s, the first full-fledged self-regulating cable with a polymer matrix began to appear on the market. First, these are cables manufactured by Raichem (USA), then Heat Trace (England), BARTEC (Germany), etc.

In the CIS countries, the cables from the above-mentioned manufacturers arrived in the late 90s and, due to their high cost, were initially used only in heating systems for gas and oil pipelines. Then, in the 2000s, a more affordable self-regulating cable appeared from South Korea, where some factories bought the secret of the matrix production technology. Around the same time, individual European and American manufacturers began to produce products under their own brand in factories in China. However, in the future, these factories were allowed to produce their own unbranded cable with the lack of quality control of Western manufacturers. As a result, prices for this product have decreased significantly, and now the average price of Samreg for anti-icing is $5-7 per 1 linear meter. However, there are Chinese samples for $3-4. Naturally, this does not apply to high-temperature specialized cables for industrial purposes, where the price for 1 linear meter reaches $50 or more.

Currently, some Russian manufacturers claim to have the technology for producing a self-regulating matrix. However, the quality of such a matrix is ​​still very crude, the inrush currents are high, and the service life is very limited. Therefore, their main line of expensive cables for industrial electrical heating is produced on the basis of a matrix purchased from European or American factories.

Heating cable management systems

Almost all electric heating systems, except the most primitive ones, are equipped with a set of temperature, current, voltage sensors, control devices and information collection systems. The purpose of control subsystems (hereinafter referred to as control systems) is not only to support a given system operation algorithm, but also to provide maintenance personnel with information about its functioning.

Considering the currently available electric heating control systems, we can come to a paradoxical conclusion: customer enterprises use the most modern systems from leading manufacturers as process control systems, and the most primitive systems based on simple capillary thermostats are used as electric heating control systems. However, in the case of explosion-proof design, capillary thermostats are offered by manufacturers for very significant money.

Electric heating control systems using capillary thermostats

Let's consider a typical heating circuit control circuit based on a self-regulating heating cable using a capillary thermostat.

Block diagram elements:

1. Power line.
2. Automatic switch (protection against overcurrent and short circuit current).
3. Residual current device/residual current device (RCD).
4. Thermostat.
5. Thermostat sensing element/temperature sensor.
6. Heating section power cable.
7. Connecting box.
8. Heating cable.
9. Heated pipeline.

Disadvantages of a control system using capillary thermostats:

• The need to install additional expensive RCD devices.
• Lack of monitoring and identification of increasing trends in the value of ground leakage current during operation. The fact that the heating cable fails in winter will significantly complicate repair work and cause failures in the operation of process equipment.
• Lack of control over the overheating of the heated technological surface during the technological process, in which the temperature may exceed the maximum value for this type of self-regulating heating cable, which will lead to premature failure of the cable.
• Lack of control of underheating of the heated surface during the technological process, in which the temperature may drop below the permissible value for this technological process. This temperature should not be confused with the temperature at which the heating element turns on.
• Lack of control of the minimum current consumption value of the heating section.
• Lack of control of the maximum current consumption value of the heating section.
• Lack of inrush current limitation function, i.e. stepwise supply of supply voltage to a heating cable located at a low temperature to limit the amount of inrush current.
• Lack of monitoring function for the main operating parameters of the heating cable during the summer shutdown of the electric heating system.
• Lack of a function for monitoring energy costs for the operation of the electric heating system to determine the efficiency of its operation as part of the enterprise's energy saving program.

Conclusion:

Electric heating control systems based on a self-regulating heating cable using capillary thermostats can be used in non-critical areas with a small number of heating sections and are of little use for controlling and monitoring electrical heating of main technological facilities in the oil and gas industry.

Taking into account the above information about the design and operation features of self-regulating heating cables, we can conclude that it is necessary to use specialized systems as electric heating control systems. Since the costs of troubleshooting, repairing and replacing heating sections, and downtime costs increase with the size of the industrial facility, the above systems can be recommended for use during new construction or can be added during subsequent operation.

Electric heating control systems using specialized controllers

Block diagram elements:

1. Power line.
2. Automatic switch (protection against overcurrent and short circuit current).
3. A controller designed to control 10 heating circuits.
4. Temperature sensors.
5. Heating section power cable.
6. Connecting box.
7. Heating tape.
8. Heated pipeline.
9. Interface module.
10. Distributed process control system (DCS).
11. Automated workstation (AWS).

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Advantages and disadvantages of self-regulating heating systems

Advantages:

• No overheating. Self-regulating thermal cables can be overlapped without any risk of overheating. Their intersection with each other does not cause any harm. This is of no small importance for control-closing mechanisms, for example, when you need to wrap a valve on a pipe. It also happens that the heating cable in anti-icing systems becomes covered with dirt, leaves and other debris. In this case, an ordinary resistor will burn out while the samregs will work reliably;
• Convenient cutting. Such cables can be cut from a common coil to the required length immediately on site “in the field”. This provides additional flexibility when plans do not match the “real life” situation on site. Such connections can be divided into pieces of the required length with a maximum length of up to 0.7 - 0.15 km (depending on the type of samreg). In contrast, resistive cables have a clearly defined length;

• Self-regulation. During operation, there is no need to install complex multi-channel thermostats, because the cable sharply reduces power after reaching a certain threshold temperature. This mode is ideal for anti-icing systems, where it is often very difficult to maintain the desired temperature along the entire length of the section. Samreg itself finds the appropriate temperature for each zone;

• Saving electricity. Due to the point release of heat where it is required and minimal heat release in places that do not require heating, a self-regulating cable is much more economical than a resistive cable. In anti-icing systems, a resistive cable is usually connected to one temperature sensor and generates heat where the sensor is located and heating is required, and in places where it is not needed.

Flaws:

• Starting power. When installing, it must be borne in mind that the initial voltage can be maximum twice the operating rated voltage, and the supply network must cope with this. A similar situation arises with the selection of control equipment of suitable power;

• Limited heat dissipation. It is impossible to increase the temperature in the room using this connection in a short time. When the room heats up, the power of the cable drops, and it stops heating the surrounding room just as intensely;
• Relatively high cost. The price per 1 linear meter of self-regulating cable is 2-3 times higher than that of a constant power cable. This can immediately scare off a consumer who does not understand the issue. If you count the energy savings and other advantages, then such an increase in price is quite justified;
• Relatively short length of one section. Depending on the type of cable, the maximum length of a self-regulating cable cannot exceed 65-120 meters. Resistives have many times longer lengths. This imposes the task of installing additional power points;
• Limited service life. On average, such a cable lasts about 10-15 years. Next, its matrix begins to degrade and significantly reduce power down to 0.

Reliability of heating cables

Basically, when asked about reliability, sellers and manufacturers state the following:

• Our products are manufactured using the most modern equipment, under strict quality control.
• Some of our cables have been used without any problems for decades at certain facilities.

Is this information sufficient for the consumer?

Let us consider in more detail the issues of ensuring the reliability of cable heating elements. The reliability of cables is determined by their ability to perform their functions under given conditions for a given time. The main task of a particular cable product is determined by its purpose and design. Heating cables are designed to release a heat flux of a given specific power. Loss of performance of the tapes occurs when there are any failures. Typical types of failures of heating cables are: breakage of conductive elements, violation of the integrity of insulation and protective covers, an increase in conductor resistance above the maximum permissible standards, degradation of the heating semiconducting matrix and a corresponding decrease in heat-generating capacity.

Taking into account that a decrease in heat-generating capacity is a fundamental defect of a heating cable that affects the operation of an electric heating system, let us consider the following indicator of the reliability of heating tapes - the minimum operating time.

Minimum operating time

When applied to cables, this concept implies a period of time during which there should be no failures in the cable product. At the same time, the probability of random failures is extremely low and they are caused by design and technological flaws or violations of operating conditions. It is recommended to set the minimum operating time in the form of one of the values ​​of the standardized series: a minimum of 500 hours and a maximum of more than 150,000 hours. It is possible to set the operating time in the form of a number of cycles - for example, on-off cycles.

For a self-regulating cable, the number of on-off cycles is a very important factor that determines the aging of the semiconducting heating matrix.

When developing new cable products, to assess their reliability, it is customary to conduct direct reliability tests to confirm a minimum operating time of 1000 hours. Specimens selected for testing are subjected to repeated test cycles. The sequence of actions in each test cycle and the number of cycles must be determined in the test program. The number of tested samples required to confirm the probability of failure-free operation of the product at the level of 0.9 with a reliability of 0.9 is 22 samples. With such a test setup, the expected number of failures (the so-called acceptance number) should be equal to zero. If one failure is allowed, the sample needs to be increased to 37 samples. Testing to obtain a greater probability of failure-free operation requires a significant increase in the number of samples, and therefore greater costs. Confirmation of operating time greater than 1000 hours significantly increases the complexity of testing.

To confirm the operating time of 1000 hours, it is recommended to request test results from the heating cable manufacturer to confirm the above reliability indicator.

The deceptive illusion of absolute reliability of cable products reduces consumer attention to such issues as facilitating operating conditions and constant monitoring of key parameters during the technological process. The main share of failures of cable products occurs when the products are operated in unacceptable modes, due to unacceptable influences that occurred during installation, or in the presence of manufacturing defects. Technological reliability, determined by the uniformity of product characteristics and the stability of technological processes, does not take into account the dynamics of changes in the characteristics of heating elements and other components of heating systems over time. With sufficiently intense heating of the tapes and simultaneous exposure to the external environment (temperature, moisture, vibrations and shocks, etc.), the polymer coatings age and the conductors oxidize. Periodically, subsequent heating and cooling cycles during operation can cause unwanted mechanical stress and degradation of the heating matrix.

Types and types of “samregs”

In household electric heating systems, a low-temperature self-regulating cable is mainly used, which can withstand heating up to 85 C. Medium-temperature and high-temperature cables have significantly greater heat resistance and are usually used in the mining and manufacturing industries.

Self-regulating cables and tapes are classified according to their purpose:

• For heating household pipes;
• For anti-icing systems (heating of roofs, gutters, paths, platforms);
• For industrial heating (heating of oil and gas pipelines, industrial tanks).

Based on the presence of braided shielding, cables are divided into:

• Shielded – with a protective grounding shield;
• Unshielded - without protective braiding and grounding.

Due to the presence of a screen, the price of the cable increases by 2 times, therefore, in ordinary domestic heating areas that are not subject to mechanical stress and have little contact with humans, it is rational to purchase an unscreened version.

According to linear power (power per 1 linear meter), there are the following main types:

• 10 W/m. – for heating inside pipes;
• 15 W/m. – for heating inside and outside pipes;
• 24 W/m. – heating of roofs, paths, outside pipes;
• 30 W/m. – heating of roofs, pipes and anti-icing systems;
• 40 W/m. – heating of roofs, gutters, valleys, anti-icing systems.

There is also a classification according to the type of outer shell:

• With food casing - for heating inside water pipes and sewers;
• With UV protection – for placement on roofs and places where there is a lot of ultraviolet radiation emitted by the sun.

In addition to the above, there are highly specialized cables for industrial heating, a description of which can be found in the corresponding section of our website.

Reliable and environmentally friendly insulation

Insulation based on a high-molecular polymer compound (polyolefin) reliably protects the heating part of Heatus kits for outdoor installation ARDpipe from a variety of mechanical influences: from impacts, repeated kinks, and so on. Thanks to this quality, the ARDpipe cable is a simple tool for solving complex problems: it can protect against freezing and extend the life of engineering systems laid in complex and problematic soils. Heatus outdoor cable is designed for heating utility lines made of various materials. The maximum diameter of the serviced pipeline is 200 mm.

The self-regulating cable, which is included in the PerfectJet work kits, was specially designed for internal installation (for installation inside utility lines). These products are additionally coated with a protective food coating, which is impossible not to note when considering the distinctive characteristics of PerfectJet kits. Very often, such a conductor is used to heat water mains, and the presence of a food casing in this case is a logical requirement of sanitary and environmental standards. The food casing from Heatus reliably covers the markings applied to the cable, which distinguishes the products of this brand from analogue products in which the markings are applied on top of the food casing.

Application in the national economy

• In construction work, self-regulating cables are used to protect communication systems from icing. In this case, the electrical connection can be located in the inside of the pipeline and on the outside. This circumstance is important when the pipeline from a well or sewage disposal system is laid on the soil surface, and it needs to be protected from icing in the cold season. The situation is similar with foundations located at shallow depths. In this case, the pipeline running from the pumping station to the comb, where the control units are located, also requires additional protection from the cold. Here you should take into account the possibility of cutting off part of the connection of the required length, which will greatly help optimize the electricity consumption required for this system.

To increase the temperature in the internal part of the fresh drinking water supply, compounds are used, the hygienic safety of which is confirmed by a special document. Such cables are installed using special glands and interact with drinking liquid. These are profile connections approved by environmental control organizations;

• To protect against the formation of ice on stairwells, landings, parking lots, and devices for lifting wheelchairs in order to prevent people from receiving various injuries, appropriate temperature increasing systems are also used;

• To protect the roof and its elements from cold , to prevent icing of water removal systems from the roof. Installing a cable can prevent the formation of ice crusts and icicles. If these steps are not taken, damage may occur to the roof, water removal pipes, and cable networks. Falling ice formations from the roof can cause damage to both property and the life or health of people;

• In the gas, chemical and oil industries to increase the temperature inside pipes in a cold atmosphere (in order to prevent them from icing); to increase the temperature of pipes to increase the permeability of substances flowing through them (in order to prevent the appearance of very dense formations and narrowings that interfere with permeability);

• To regulate the temperature of tanks with oil industry products (oil, bitumen, tar, etc.). The same is true for chemically active solutions, substances, etc. Security measures make it possible to prevent property damage;

• In the food industry , they increase the temperature of the drainage pipes of refrigeration units, generate evaporation in refrigeration units, warm drainage trays from the compartments of refrigeration units, and increase the temperature of the crankcases of piston types of pumps before activating them in cold conditions. In addition, self-regulating cables increase the temperature of individual food, fresh water and fire-fighting tanks;
• To increase the temperature of the earth's surface in various agricultural buildings, including greenhouses and premises for keeping livestock. Due to systems based on electrical connections capable of automatic regulation, it becomes possible, at low cost, to create comfortable conditions in such buildings throughout all seasons of the calendar year, which has a good impact on the agricultural industry as a whole.

Additional benefits

To purchase a truly high-quality and certified product, a buyer living somewhere in the periphery is usually forced to travel many kilometers. The issue of purchasing a Heatus heating cable is solved much easier: the supplier’s developed dealer network has a wide coverage. At the same time, the manufacturer is open to cooperation with new business partners, offering them favorable and attractive conditions.

Also, every retail customer can purchase Heatus products through the online store - this is the optimal solution for those who are far from the company’s official representatives. Buying online, delivery by popular transport companies and the ability to purchase a heating cable of suitable length and power are advantages that are difficult to overestimate.

Tips for choosing

When choosing a self-regulating cable, you don’t always need to focus on price. You need to consider what you will use it for and under what conditions it will be used. Here are some points you need to know before purchasing:

• Cable power. To heat pipes from the outside, cables of 16-30 W/m are usually used; if the cable heats the pipe from the inside, then 10-15 W of linear power is quite enough. For roofs and gutters, samregs with a power of 30-40 W/linear m are usually used;
• UV protective shell. If the cable will lie in the open sun and will be exposed to UV radiation, then you need to buy a cable with UV protection;
• Grounding braid. Self-regulating cables are sold both with and without a grounding braid (screen). The price of a cable without ground is about 1.5-2 times cheaper. It is advisable to use it for heating pipes going into the ground, wells, and on roofs. The most important thing is to seal this cable with a reliable adhesive seal to ensure protection against water penetration. A cable with a screen is safer, however, but much more expensive, which is not always justified, especially since they have the same self-regulating heating matrix. It determines the durability of the cable and in this regard, a cable with the same service life will significantly differ in price;

• Starting power. When any self-regulating cable is turned on, its power consumption is higher than the rated one. With a good quality self-regulating wire, the power increases by 20-50%; with a low-quality samreg (usually made in China), the starting power can “soar” significantly. This indicates the instability of the matrix and its fragility. Also, low-grade cable requires more powerful power supply machines;

• Air cavities. When purchasing, you need to squeeze the cable with your fingers and run them along its length. A low-quality cable is not manufactured according to standards and air cavities will be felt inside it. There will be a feeling that the outer sheath is lagging behind the internal parts of the cable. And, conversely, if the production process is streamlined and the technology is followed, then the outer sheath sits tightly on the cable and forms a single whole with it;
• Thickness. Self-regulating cables usually have a width of about 1 cm and a thickness of 3-4 mm. In the markets of Minsk and in the regions, sellers, trying to attract buyers with a “red” price, slip in Chinese cable. It comes to the point that its width is a little more than 0.5 cm. With such a thickness, the area of ​​heat generated is much lower and such a samreg is much less efficient. And if a matrix, which is 2 times smaller in size, generates similar heat, then its service life is short-lived. In addition, there is a possibility that over time the supply wires may close with each other due to the fact that in some places the heating matrix melts or collapses.

Tip 5. Pay attention to installation methods

Outdoor installation

For this option, you can use any type of heating cable.

Advantages:

1. Easy to install. Work can be done alone.
2. Does not reduce the overall pipe capacity.

6 ways to lay outdoor cable

1. It is enough to tape the conductor with special tape to small cross-section pipes. Suitable for areas with mild climates.
2. Where climatic conditions are more severe, the cable is wrapped around large cross-section pipes. The lower the temperature, the denser the turns.
3. When using a resistive conductor, when completing the winding, the second end can be returned to the starting point.
4. We avoid superimposing one turn on another, that is, overlapping, since overheating is possible during operation.
5. The average step is 5 cm.
6. The material should fit snugly to the surface without sagging.

Before installation work, we prepare the outer surface of the pipe. We remove traces of corrosion and dirt from metal. The plastic one needs to be wrapped in foil.

Internal installation

Only two-core resistive heating cables are used for pipe cross-sections of 40 centimeters or more. Conductors that are inserted to a predetermined length. To use a self-regulating conductor, external protection must have a class of at least IP68.

At the point of output and connection to the network, a coupling is screwed on to seal the installation. There are restrictions: they must only be solid, without joining elements.

Tip 6. Seven basic recommendations

1. For pipelines with variable temperature conditions, only a self-regulating cable is suitable. Especially in a situation where one part of the pipeline system is located indoors, and the other is underground or in the air. Resistive cable is energy inefficient.
2. It is recommended to select the right insulating materials to make the system energy efficient.
3. When winding, you need to clarify to what extent the bending of the material is allowed. If bent, rapid failure may occur.
4. For household systems, a relay is connected to the cable to prevent current leakage.
5. For the self-regulating conductor version, the use of a temperature sensor is recommended. It is set to turn on at a temperature of +3 and turn off when it reaches +13 degrees Celsius.
6. When laid lengthwise, the length of the material is equal to the size of the pipe, with a certain margin. When winding, you need to take 1.6 - 1.7 pipe lengths.
7. The sensor is isolated from the heater surface. It is important that the connection to the pipe is as tight as possible.

Features and advantages of constant power cable products

The cables have a round cross-section. They are endowed with such positive characteristics as:

• high design flexibility, allowing bending in any direction;
• the presence of PTFE insulation, which guarantees protection of fragile elements from mechanical damage;
• high heating power;
• ability to withstand the negative effects of extreme temperatures (200-260 degrees).

When making heating cables, experts use zonal parallel elements with current-carrying conductors wound around them. The gap between their contact points is decisive when measuring the heating zone. Thanks to the parallel design, the product can be cut and ringed for maximum ease of installation. On the website https://elix.ru/greyushhij-kabel/raychem/fmt-and-fht/20fmt2-ct-(1244-006058) constant power cable products can be purchased in different versions. They are distinguished by their ability to withstand steaming and the influence of temperatures reaching 260 degrees.

Why does a self-regulating conductor need a thermostat?

Despite the fact that this type of cable independently regulates the amount of thermal energy released, when passing through the zero mark, the functional features will continue to heat the surface, albeit at low power.

For controlled flow you will still need a thermostatic device , especially if you are using a conductor longer than 10m.

By connecting a thermostat , you just need to set the desired temperature level and not worry about extra costs due to climatic fluctuations in the surrounding area.

Pipe heating application

The thermostatic cable is used for heating pipes with a diameter of more than 40 mm.

Features of installing a heating system inside a pipeline

The heating cable is placed inside the pipe if external installation is not possible. It is pushed inside the pipe and connected to the electrical network using a special heat-shrinkable sleeve.

The heating cable is laid inside the pipe.
It is not allowed to pass the wire through shut-off valves and other shut-off equipment to avoid damage.
It is highly advisable that this work be carried out by a qualified electrician, since work on installing electrical equipment inside the water supply system is highly dangerous in case of installation errors.

The heating system does not require additional service or maintenance.

How to attach over a pipe?

There are two main ways to attach the cable. Parallel (linear) and circular.

With parallel (linear) installation , it is fixed on top of the pipe. The length of the cable in this case is equal to the length of the heated area.

Parallel installation of heating cable outside the pipe

The possibility of self-regulation of the cable allows the use of overlap when it is necessary to heat external locking structures. Cranes, valves, meters, inserts.

It is necessary to ensure its tight fit to the heated surface. To do this, you must clean the surface of the pipe.

With a circular fastening , the cable wraps around the pipe with a turn pitch, according to the specification.

After completing the work, you should wrap the resulting system with aluminum tape for securing and shielding. In order to reduce heat loss, it is recommended to add thermal insulation.

During installation, it is strictly forbidden to use plastic tape instead of aluminum tape.

Installation features

Cable laying should be carried out in a favorable thermal zone.

At temperatures below -5 degrees, installation is prohibited. This limitation is due to the structure of the polymer within it.

When laid in low temperatures, it may be damaged.

How to lay a wire if it has lost its flexibility at 0 degrees?

After carefully unwinding the coil, it is plugged into the network for about a minute. The cable will restore flexibility. After this, installation can be carried out.

It is highly not recommended to connect an unwound wire to the network.

Features of installation of constant power cables

The process of installing cable products intended for heating is not particularly labor intensive, but requires the use of complex monitoring and control systems. At the first stage, the cable is fixed to the surface that needs to be heated. To do this, you can use heat-resistant aluminum tape or other material that can withstand high temperatures. The next steps include removing the external silicone protection, removing the resistive film from the exposed areas, installing the electrical insulating cap, separating and insulating the contacts.

You can ensure a long service life for cable products by using high-quality products that are in perfect technical condition. Therefore, before carrying out any work, it is necessary to check each meter section, connecting it to the electrical power supply.

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Main settings

Before purchasing a product, you should consider the main parameters by which these heating cables differ:

• type: self-regulating cables or resistive;
• external insulation material;
• absence or presence of a screen (braid);
• temperature class;
• power.

Note!
You should know that there is no universal option for all occasions. Because of this, before you go to the store, you need to understand what you can expect from your heating system. What purpose will it serve?

In general, the scope of application of such elements can be divided into three main categories:

1. Use for domestic purposes. We are talking about cottages, dachas, country houses. In this case, a high power cable will not be required.
2. Communal use. This includes water supply, drain heating system, and sewerage system.
3. Use in industry. For this purpose, powerful heating systems and high temperatures are already required.

Having decided on your goal, you can study the basic parameters.