I. Definition of Railway Digital Signal Cable
Digital cable refers to a kind of cable capable of transmitting digital signals with the ability of high-speed transmission and long-distance transmission, which is widely used in the fields of communication, data transmission, control system and so on. At present, the application of digital cables in the field of railroad transportation has been very extensive and has achieved remarkable results. Digital cables can improve the efficiency of railroad system operation, while playing a key role in communication transmission and signal control.
Railroad digital signal cable has the function of transmitting analog signals (1MHz), digital signals (2Mbit/s), rated voltage AC 750V or DC 1100V and the following system control information and power transmission. Apply to the railroad signal automatic blocking system, counting axis, station electric code, computer chain, microcomputer monitoring, scheduling centralized, scheduling supervision, high-power electric rutting machine and other related signal equipment and control devices between the transmission of control information, monitoring information and electrical energy.
Second, the characteristics of railroad digital signal cable
Advantages
Cable has high mechanical strength, good corrosion resistance, cold resistance, high shielding performance, can meet the electrified railroad on the strong electric field interference, humidity, cold and other environmental requirements as well as the existing signaling system of the latest system, the latest equipment supporting the requirements; at the same time, the cable is compatible with other systems of signaling system equipment. In addition, the cable can be used according to the environmental requirements, with flame retardant, termite-resistant additional features.
- Strong anti-interference: railroad digital signals in the transmission process is prone to environmental interference, railroad digital signal cable to improve the anti-interference ability between the line group, to achieve the same frequency with the cable transmission, and when the core ground fault state of shielding between the group crosstalk interference with the two signal cable cable is equivalent to sub-cable, effectively improving the safety of the system. Internal shielded railroad digital signal cable to meet the original railroad signal cable indicators on the basis of improving the overall electrical performance of the cable: AC rated voltage increased by 1.5 times, capacitance indicators reduced by 40%, insulation resistance indicators increased by 2.3 times, while improving the impedance, attenuation, crosstalk and other properties.
- High reliability: digital cable has high reliability, for the transmission of data and signals with high quality requirements can ensure the reliability of transmission and guarantee the safety of the railroad system.
- Safe and stable: railroad digital signal cable in the design and manufacturing process to consider the safety factors, can prevent fire, short circuit and other accidents. At the same time, it also has good moisture-proof performance and corrosion resistance, and can work normally in harsh environmental conditions.
- Long-distance transmission: railroad digital signal cable can support a longer transmission distance, which can meet the needs of railroad lines. At the same time, the stability and reliability of its transmission signal can also be guaranteed.
Third, the application of railroad digital signal cable
- Signal transmission: railroad signaling system control signals, fault signals, etc. need to be transmitted through the cable. Railroad digital signal cable can accurately and stably transmit these signals to ensure the normal operation and safety of the railroad.
- Data transmission: data transmission and communication are needed in railroad equipment and system, such as train position information, equipment status monitoring, etc. Railway digital signal cable can meet these requirements. Railroad digital signal cable can meet the needs of these data transmission and ensure the accuracy and real-time data.
- Monitoring system: railroad digital signal cable can also be used for railroad monitoring system, used to monitor the safety and stability of railroad lines. Through the transmission of signals, potential problems can be found and solved in a timely manner to ensure the normal and safe operation of the railroad.
Fourth, the structure of the railroad digital signal cable features
1.Insulated single-wire structure
Insulated single wire insulation layer for the skin – bubble – skin structure, a total of red, green, white, blue four color spectrum, the use of internationally advanced three-layer co-extruded tandem line manufacturing, i.e., the conductor pulling and skin – bubble – skin structure of the insulating layer of extrusion is completed at a time to achieve the product structure dimensions and performance indexes of the on-line testing and control of the precise manufacturing, the main advantages of which are:
- a. The inner skin insulation layer can be well bonded together with the conductor to ensure that the insulation layer of moisture resistance and bonding firmness; foam insulation layer for the nitrogen physical foaming, compared with the traditional chemical foaming bubble holes are small and dense and are not connected to each other, and thus has a high degree of foaming (60% or so), the insulation layer of the foam means that the four-wire group of capacitance decreased, the line transmission attenuation constant is reduced.
- b. The outer skin layer uses high-density insulating material with good abrasion resistance and mechanical strength, and the environmental aging resistance is more than 10 times that of ordinary polyethylene material, which fundamentally solves the problem of aging and cracking of the insulating layer existing in ordinary railroad signal cables.
- c. As a single line of color masterbatch exists only in the outer skin layer, insulation resistance and voltage breakdown strength significantly improved, is more than 3 times the ordinary railroad signal cable. As a result of single-wire production process to achieve the computer online testing and control, single-wire structure and size of the consistency of good, working pairs of DC resistance difference reduced by 50%.
- d. Insulated single-wire manufacturing precision, effectively improving the product’s electrical performance indicators.
2.Four-wire group twisted structure
Four-wire group using advanced high-speed star stranding machine production, each single wire are active constant tension payoff, unique twisting pre-twisting device, the unique design of the product performance indicators such as open wire, pre-twisting device can effectively reduce the capacitive coupling coefficient due to the insulation eccentricity caused by the capacitive coupling coefficient to reach the minimum value; precise yarn tension that is to ensure the symmetrical stability of the four-wire group structure, but not to make the skin – bubble – skin structure Insulation layer deformation and damage; four-wire group stranding pitch accuracy, line sequence, outside diameter control are the key links in this process, but also affect the product performance indicators of the key factors.
3.Four-wire unit shielding structure
The four-wire group unit in the inner shielded cable is longitudinally wrapped with copper tape to realize the purpose of electromagnetic shielding, and a copper wire is added along the surface of the copper tape as a drain line to ensure that the shielding layer has stable and reliable shielding performance in the construction and long-term use of cable laying.
4.Characteristics of the cable
In order to improve the crosstalk indicators of the cable, in the cable formation process, reasonable design, matching the stranding pitch, and realize the complete de-twisting stranding, reducing the direct systematic coupling between the wires, to achieve the purpose of reducing the crosstalk.
As many as four different structures, different sizes of cable units, in the process of stranding how to ensure that the core of the rounded, stable and compact structure is the key to the process of cable formation, and must ensure that the core of the line sequence and group sequence is completely correct.
5.Cable aluminum sheath structure
Aluminum cable sheath for the use of argon arc welding technology for the longitudinal wrapping of aluminum tape to form an aluminum sheath. In order to prevent the use of aluminum sheath in the process of electrochemical reactions, the production process of aluminum sheath surface coating.
Aluminum sheath cable for the trunk line cable, the largest amount of use, so the aluminum sheath process capacity and quality is also a key link in the manufacturing process of the product. Aluminum sheathing of cables produced by TIG welding technology has stable and reliable welding quality, and can fully withstand the bending test, flaring test and air tightness test according to the relevant standards.
Fifth, why choose TST CABLES production of railroad digital signal cable?
TST CABLES railroad signal cable compared with ordinary railroad signal cable, although some of the ordinary railroad signal cable product quality has great advantages and technological breakthroughs, but according to the actual testing and field use, the product in the following performance indicators need to be further improved TST CABLES railroad digital signal cable through the structure of the design and process measures, the operating Capacitance is reduced from 50nF/km to 29nF/km, and the average value of capacitive coupling K1 is reduced from 141pF/km to 81pF/km, meanwhile, impedance, attenuation, crosstalk, and other secondary transmission performance indicators are increased. Ordinary rail transit digital signal cable products used in the process of conductor mixing line, broken line and oxidation; secondly, the insulation layer of tensile strength, elongation at break, compression resistance to improve the performance of the improvement of the improvement of the improvement of the performance of the insulation layer; lastly, the range of some of the secondary parameters in the current standard is not set up ideally, and it is difficult to match the correlation of the secondary parameters and the indicators of each frequency point to the ideal median value. In particular, the insulation strength, is the user (Ministry of Railways engineering units), product quality supervision and testing centers and manufacturers of divergent and very concerned about the issue, which is not only the cable manufacturing enterprises are facing a new technical challenge, at the same time will be due to the improvement of the insulation strength of the product structure caused by the improvement of the size of the product, the performance indicators and the current standard has a large deviation.
It is worth noting that in the Chinese railroad put into operation in the automatic blocking system, ZPW-2000A automatic blocking system is currently the main use of new railroads and electrification transformation line system. Its supporting cable for the internal shielding railroad digital signal cable (TB/T3100.5-2004), which is a high technology content, the market with the largest amount of cutting-edge products. The signal cable of other signaling system has a smaller amount and shows the trend of being gradually eliminated.
Railroad digital signal cables play a vital role in the railroad system, they not only ensure the high-speed, stable and safe transmission of signals and data, or an important guarantee for the safety and stability of the railroad system.TST CABLES, as a leader in the cable industry for 20 years, focusing on rail transportation cables for 11 years, TSTCABLES rely on a strong innovative ability and technology development level, and constantly invest in product development. TST CABLES relies on strong innovative ability and technical research and development level, continuous investment in product development and improvement, and adhere to the “zero defects, zero complaints, zero errors, zero rework” quality standards for urban rail transit provides a complete set of safe, environmentally friendly cable solutions, favored by customers, innovation and breakthroughs in the field of rail transportation cables, leading the industry development and progress.
If you have any questions or needs for high quality rail transit cables, railroad signal cables, you are welcome to contact us by email at any time.
