EAC certified low-temperature instrument cable

EAC certified low-temperature instrument cableScope of Application

Instrument control cable is a PVC insulated and PVC sheathed control cable suitable for use in industrial and mining enterprises, energy and transportation departments, and for controlling and protecting circuits with AC rated voltage below 450/750 volts.

Performance Characteristics

1. DC resistance: 20 ℃, 0.4mm copper wire, less than or equal to 148 Ω/km, 0.5mm copper wire, less than or equal to 95 Ω/km.

2. Insulation electrical strength: no breakdown between conductors at 1kV for 1 minute, and no breakdown between conductors and shields at 3kV for 1 minute

3. Insulation resistance: Each core wire is grounded with the remaining cores, and the control cable is greater than 10000M Ω· km, while the HYAT cable is greater than 3000M Ω· km.

4. Working capacitance: average value 52 ± 2nF/km

5. Remote Crosstalk Defense: At 150kHz, it refers to the average power of a certain combination being greater than 69dB/km.

Applicable environment:-60 ℃~+45 ℃ (-20 ℃ to+120 ℃ optional)

Product Certification

Implement standards IEC60227, EN50575, EN13501/6, and GB/T 9330-2008. Flame retardant cables should also comply with the technical requirements of IEC337-8 standard.

Customs code 854421100

Product Model Classification

Performance difference

Control cables have the characteristics of moisture resistance, corrosion resistance, and damage prevention, and can be laid in tunnels or cable trenches. Power cables are used in the backbone of the power system to transmit and distribute high-power electrical energy. Control cables directly transmit electrical energy from the distribution points of the power system to the power connection lines of various electrical equipment and appliances. The rated voltage of power cables is generally 0.6/1kV and above, while control cables are mainly 450/750V. When producing power cables and control cables of the same specifications, the insulation and sheath thickness of power cables is thicker than that of control cables.

（1） Control cables belong to electrical equipment cables, and power cables are two of the five major categories of cables.

（2） The standard for control cables is 9330, and the standard for power cables is GB12706.

（3） The color of the insulation core of control cables is generally black with white lettering, and low-voltage power cables are generally color coded.

（4） The cross-sectional area of control cables generally does not exceed 10 square meters, while power cables are mainly used for transmitting electricity and are generally large in cross-section.

Due to the reasons mentioned above, the specifications of power cables can generally be larger, up to 500 square meters (the range that conventional manufacturers can produce), and there are relatively few manufacturers that can produce even larger cross-sections. On the other hand, the cross-section of control cables is generally smaller, with a maximum of no more than 10 square meters.

material

The core of the control cable is copper core, with a nominal cross-sectional area of 2.5mm2 or less, and 2 to 61 cores; 4～6mm2, 2-14 cores; 10mm2, 2-10 cores. The working temperature of the control cable is divided into two levels: rubber insulation at 65 ° C and polyvinyl chloride insulation at 70 ° C and 105 ° C. The control cables used in computer systems are generally insulated with polyvinyl chloride, polyethylene, cross-linked polyethylene, and fluoroplastic. Instrument cables used in low-temperature environments in the Far East region such as Russia require special low-temperature resistant materials to be made.

Technical Specifications

Rated voltage: U0/U is 450/750V.

The long-term working temperature of the conductor core is 70 ℃ and 95 ℃, and the cable laying temperature is generally not lower than 0 ℃.

The recommended allowable bending radius for cables is as follows:

Unarmored cables should not be less than 6 times the outer diameter of the cable;

Armored or copper tape shielded cables should not be less than 12 times the outer diameter of the cable;

Shielded flexible cable, not less than 6 times the outer diameter of the cable.

Control cables generally refer to equipment instrument power supply/signal control

Representative models: KVV/KYJV/and other instrument cables, etc

Installation measures

The rated voltage of the instrument control cable should not be lower than the working voltage of the circuit, and should meet the requirements of transient and power frequency overvoltage that may be experienced. [3] To ensure that the control cable reduces the affected area in the event of insulation breakdown, mechanical damage, or fire, the national standard GB50217-91 "Code for Design of Cables in Power Engineering" stipulates that for two systems that require enhanced reliability, including dual protection current, voltage, DC power supply, and trip control circuit, independent control cables should be used.

After the instrument control cable is put into operation, there is an issue of electrical interference between different cores of the same cable and between adjacent parallel cables. The main causes of electrical interference are:

(1) Due to the electrostatic interference generated by the coupling of capacitors between cores caused by external voltage;

(2) Due to electromagnetic induction interference caused by the current passing through. Overall, when there are high voltage and high current interference sources nearby, electrical interference is more severe. Due to the smaller distance between the cores of the same cable, the degree of interference is much greater than that of adjacent cables laid in parallel. For example, in the control circuit of a phase separated operation circuit breaker in a certain ultra-high voltage substation, the three phases share one cable. Such an accident once occurred, where the pulse of the phase separated operation triggered the thyristors of other phases, resulting in three-phase linkage. Later, separate independent cables were used, and no further misoperation accidents occurred. For example, in the computer monitoring system of a certain power plant, the use of a four core cable to share the low-level analog signal line with the power line of the transmitter caused interference voltage of 70V on the signal line, which obviously affected the normal operation of the low-level signal circuit measured in millivolts.

The measures to prevent or mitigate electrical interference mainly include the following three aspects.

1. One spare core of the control cable is grounded

Practice has shown that when a spare core is grounded in a control cable, the amplitude of the interference voltage can be reduced to 25% to 50%, and the implementation is simple, with little increase in cable cost.

2. Do not use a single control cable for circuits that can cause serious consequences when subjected to electrical interference

This includes: (1) weak current signal control circuit and strong current signal control circuit; (2) The circuit of low-level signal and high-level signal; (3) The weak current control circuits for each phase of the AC circuit breaker phase separation operation should not use the same control cable. However, if each pair of round-trip wires in the weak current circuit belongs to a control cable that is not the same, it may form a circular arrangement during installation, and an electric potential may be induced under the electromagnetic wire interconnection of similar power sources. Its value may have a significant impact on the low-level parameter interference of the weak current circuit. Therefore, it is still advisable to use one control cable for the round-trip wires.

3. Metal shielding and shielding layer grounding

Metal shielding is an important measure to reduce and prevent electrical interference, including total shielding, sub shielding, and double-layer total shielding of wire cores. The selection of metal shielding types for control cables should be based on the strength of possible electrical interference effects, taking into account comprehensive measures to suppress interference, in order to meet the requirements of reducing interference and overvoltage. The higher the requirement for anti-interference effect, the greater the corresponding investment. When using steel tape armor and steel wire braided total shielding, the price of the cable increases by about 10% to 20%.

Control interference in high-voltage circuits, due to their strong signals, can be controlled by cables without metal shielding, except for those located in ultra-high voltage distribution equipment or parallel to high-voltage cables for a long time. When the control cable used in the weak current signal control circuit is located in an environment with interference effects and does not have effective anti-interference measures, it is advisable to choose a control cable with metal shielding to prevent electrical interference from causing misoperation or insulation breakdown of the low-level signal circuit. If the control cable of the weak current circuit can be sufficiently separated from the power cable or laid in steel pipes, it may reduce external electrical interference to the allowable limit.

The principle for selecting the shielding type of the control cable for the signal circuit of the computer monitoring system is:

(1) Switching signal, can be shielded with a total shield;

(2) For high-level analog signals, it is advisable to use overall shielding of the wire core, and if necessary, partial shielding of the wire core can also be used;

(3) Low level analog signals or pulse signals should be shielded separately from the wire core, and if necessary, composite total shielding containing separate shielding from the wire core can also be used.

Regarding the grounding method of the shielding layer, the following points should be noted:

(1) The shielding layer of the control cable for the analog signal circuit of the computer control system should be grounded at a centralized point. The reason is based on the requirement of ensuring the normal operation of the computer monitoring system, because even a disturbance voltage of only about 1V may cause logical judgment errors. Concentrating a grounding point can avoid the occurrence of grounding circulation;

(2) Except for the case where the control cable shielding layer of the computer monitoring system only allows centralized grounding at one point, for other control cable shielding layers, two-point grounding should be used when electromagnetic induction interference is significant, and one point grounding should be used when electrostatic induction interference is significant;

(3) The inner shielding layer of dual shielding or composite total shielding should be grounded at one point, while the outer shielding layer can be grounded at two points;

(4) When selecting two-point grounding, it should also be considered that the shielding layer will not be burned out under the action of transient current.

EAC certified low-temperature instrument cable Precautions

Precautions for installation and wiring of control cables:

1. Under the eaves. Standard LAN cables can only be used when not directly exposed to sunlight or ultra-high temperatures, and it is recommended to use pipelines. Ultraviolet (UV) - Do not use cables without UV protection in direct sunlight environments.

On the exterior wall. Avoid direct sunlight on the wall and human damage. Heat - The temperature of cables in metal pipes or cable trays is very high, and many polymer materials will reduce their service life at this temperature.

3. Inside the pipeline (made of plastic or metal). If in a pipeline, pay attention to the damage of plastic pipes and the thermal conductivity of metal pipes. Mechanical damage (repair cost) - Fiber optic cable repair is very expensive, requiring at least two terminations at each breakpoint.

4. Suspended applications/overhead cables. Consider cable sag and pressure. Is the cable directly exposed to sunlight.

5. Directly laying in underground cable trenches is the environment with the smallest control range. The installation of cable trenches should be checked regularly for dryness or moisture levels. Grounding - If the shielding layer of the control cable needs to be grounded, the corresponding standards must be followed.

6. Underground pipelines. For future upgrades, cable replacement, and isolation from surface pressure and surrounding environment, installing auxiliary pipelines for isolation is a better method. But don't expect the pipeline to remain dry forever, as this will affect the choice of cable type. Water - Moisture in twisted pair cables in a local area network can increase the cable's capacitance, thereby reducing impedance and causing near end crosstalk issues.

Model Product Name Main Scope of Application

High temperature resistant control cable (KFF cable) is suitable for signal detection in high temperature environments with AC rated voltage of 300/500 and below. Especially suitable for the control of fire and security system protection circuits and power transmission lines.

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