How to determine whether to use 6 / 10 or 8.7/10 for cable selection

When selecting cables, the power cable line design, installation and operation departments shall consider four factors, such as cable service conditions, insulation level, AAAC Cable type and conductor section, which are divided as follows.
1. Cable service conditions
(1) cable rated voltage / u () shall meet the following requirements:
1) the voltage shall meet the requirements of neutral grounding mode of power system, that is, in the neutral ungrounded power system, the voltage of non fault phase increases by times in case of single-phase grounding fault, which is related to the troubleshooting time of system grounding fault.


In IEC standard, power system is divided into three categories. Class a means that any phase conductor of the system is grounded and can be separated from the system within lmin; Class B refers to the grounding of single-phase conductor in the system, the allowable grounding fault time shall not exceed 8h, and the annual cumulative time shall not exceed 125h; Class C is a system that does not belong to classes a and B.
when the cable is used in the neutral effective grounding system, u takes the phase voltage value of the system. For example, 6 / 10kV cable is selected for 10kV system and 21 / 35kV Cable is selected for 35kV system.
When the cable is used for neutral non effective grounding system, the cable with one level higher than the system phase voltage shall be selected. For example, 8.7/10kv cable shall be selected for 10kV system and 26 / 35kV Cable shall be selected for 35kV system.
When the cable is used in class C system and single-phase grounding is allowed for long-term operation, u shall select the line voltage of the system, such as 6 / 6kV cable in 6kV system.
2) the voltage U and shall be equal to or greater than the rated voltage and maximum working voltage of the system where the ACSR Cable is located.
(2) cable transmission capacity. The cable line must meet the transmission capacity of the power system, that is, the selected cable shall have long-term allowable current carrying capacity to meet the system requirements.
For longer cable lines, the line voltage drop of the cable shall also be considered.
(3) cable laying conditions. Cables shall adapt to different laying methods, arrangement methods, metal sheath grounding methods and surrounding medium temperature, etc. The conductor of XLPE cable used for underwater laying shall have longitudinal water resistance. In order to meet the requirements of various laying environments, such as tension, compression, fire prevention, termite prevention and rodent prevention, the armor layer and outer sheath of the cable shall be made of corresponding structural materials.


2. Basic insulation level of cable
the peak value of lightning impulse withstand voltage between each conductor of the cable and the shield or metal sheath, i.e. the basic insulation level bil, shall comply with the provisions in table 1-13.
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in table 1-13, the lightning impulse withstand voltage of 220kV and above cable lines has two values, which can be selected according to the protection characteristics of arrester, the characteristic length of impulse wave of cable line and the lightning impulse insulation level of connected equipment.
3. Cable type
(1) comparison of insulation properties between XLPE and oil paper cables. XLPE insulated cable has the advantages of simple production process, short manufacturing cycle, easy installation and maintenance, excellent electrical performance and large transmission capacity. In recent 30 years, the technology of XLPE insulated cable has developed very fast and has been widely used. In terms of insulation performance, compared with oil paper insulation, cross-linked polyethylene insulation has some different characteristics, which are listed in table 1-14.
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Note: “air raid” should be “gap”
Oil paper insulated cable has the advantages of excellent electrical performance and long service life. It can be used in general occasions. However, compared with XLPE cable, the manufacturing and installation process of oil paper ABC Cable is more complex and the cost is higher.
oil filled cable with paper plastic composite insulation with low dielectric loss and alkylbenzene synthetic oil with good aging resistance as insulation structure, suitable for voltage levels of 220kV and above. In addition, oil paper insulated cables are also suitable for HVDC transmission lines.
(2) for cable lines of 110kV and below, XLPE insulated cable is generally the preferred variety. For distribution cables of 1kV and below, in addition to polyvinyl chloride (PVC) insulated cables for lines with light load, cross-linked polyethylene insulated cables shall also be selected.
Note: at present, 1-500 cables are mainly XLPE cables, and only some stocks of oil paper insulated cables and oil filled cables are left.


(3) ethylene propylene rubber (EPR) insulated cable is suitable for 35kV and below lines. This kind of cable is suitable for underwater laying because of its good moisture resistance, but its price is expensive.
4. Conductor section
copper conductors are generally used for power cables. The selection of conductor section shall meet the requirements of cable line transmission capacity and maximum short-circuit thermal stability of the system at the same time. And comply with “economic optimization of cable conductor size”.
in urban low-voltage power grid, four core cable is generally used, that is, in addition to three-phase conductor, there is a neutral line passing through three-phase unbalanced current and having protective grounding effect. The section of neutral wire shall generally be 30% ~ 60% of the conductor section of each phase. In the low-voltage power grid with large three-phase unbalanced current, four core low-voltage cables with equal cross-section shall be selected. The three core cable plus another insulated conductor cannot be used as the neutral wire to connect to the three-phase four wire low-voltage power grid, because in this way, there will be unbalanced current passing through the metal sheath and armor layer of the three core cable to heat it, thus affecting the transmission capacity of the cable.

Factors Affecting Cable Performance and Placement in Wiring

Factors affecting Aerial Bundled Cable (ABC) SANS 1418 Standard and placement in the wiring six factors affecting cable performance:

  • Ultraviolet (UV)– Do not use cables without UV protection in direct sunlight.
  • Heat — The temperature of the cable in the metal tube or groove is very high, and many polymeric materials will degrade their service life at this temperature.
  • Water — moisture in a twisted-pair cable on a LAN can increase the capacitance of the cable, thereby reducing the impedance and causing near-end crosstalk problems.
  • Mechanical damage (repair cost)– Cable repair is very expensive and requires at least two terminations at each break point.
  • Grounding — If the shielding of the cable needs to be grounded, the appropriate standards must be complied with.
  • Total length of routing (not just between buildings)– Outdoor LAN twisted pair cables are used between buildings and the total length is limited to 90 meters. For 100Mbps or 1000Mbps networks, the paved distance cannot exceed this limit. If the laying distance is between 100 meters and 300 meters, optical cable should be chosen.

Is the cable placed in:

1.Under the eaves. 4/0 Aluminum Cable can only be used when they are not directly exposed to sunlight or ultra-high temperatures. Standard LAN cables are recommended.

  1. Exterior wall. Avoid direct sunlight exposure to the wall and man-made damage.
  2. In pipes (plastic or metal).If in pipes, pay attention to the damage of plastic pipes and the heat conduction of metal pipes.
  3. Hanging applications/overhead cables. Consider cable sag and pressure. What kind of binding do you plan to use? Whether the cable is exposed to direct sunlight.

  1. It is directly laid in the underground cable trench, which is the least controlled environment. The installation of cable trench should be checked regularly for dryness or humidity.
  2. Underground pipes. In order to facilitate future upgrades, cable replacement and isolation from surface pressure and surrounding environment, auxiliary pipe isolation, auxiliary pipe is a better method. But don’t expect the pipes to stay dry forever, which will affect the type of cable you choose.

International Advanced Level of Environmental Protection Wire and Cable Indicators

Environmental protection wire refers to the material is environmental protection wire.

The material includes insulating material, conductor material and shielding material. Insulation such as PVC, irradiated cross-linked PVC (XL-PVC), irradiated cross-linked polyethylene (XL-PE), low smoke free (Halogen-free), silicone rubber, Teflon Telflon and so on. The environmental protection of insulation materials is mainly the EU’s RoHS environmental protection directive and the EU’s environmental regulations on children’s toys do not contain 6P (Non-6P), that is, does not contain phthalates. Now the most environmentally friendly is low smoke halogen-free, does not contain halogen elements.

The most common conductor material is copper. Copper has bare copper (brass, red copper), tinned copper, silver-plated copper wire, etc., which are essentially copper, but the surface is plated with other substances. Now there are copper – coated aluminum and copper – coated steel conductors on the market. If the electrical performance requirements are high, copper is the best. The environmental protection of conductors is mainly required to be free of heavy metals (RoHS).

Environmental protection cable means that it does not contain lead, cadmium, hexavalent chromium, mercury and other heavy metals, and does not contain brominated flame retardants. The environmental protection performance of the cable is tested by SGS recognized testing institutions, and it is in line with the European Union Environmental Protection Directive (ROSH) and higher than its index requirements. No harmful halogen gas, no corrosive gas, less fever when burning, no pollution of soil wires and cables.

Main technical indicators:

  1. Rated voltage: 450/750V and below
  2. The maximum permissible operating temperature of the conductor shall not exceed 70 ℃, 90 ℃ and 125℃ respectively.
  3. Cable combustion smoke density in line with GB/T 17651-1998 (equivalent to IEC1043) standard requirements, light transmittance ≥60%.
  4. Cable halogen acid content test conforms to GB/T 17650-1998 (equivalent to IEC 754-2) standard requirements.

(1) PH ≥4.3

(2) Conductivity ≤10μs/mm

  1. The flame retardant performance of the cable conforms to the requirements of GB/T 12666-1990.

6.Toxicity index of cable ≤3.

Cable selection method of generic cabling system

Generic cabling is one of the key links of information network system. In order to ensure the high-speed and stable operation of information network system, it is particularly important to select high-quality and high-performance cables.

The cable selection should be based on the system requirements, technical performance, investment estimates and other factors, but in the wiring system, it should first determine the type of cable used and the structure of wiring (unshielded cable, shielded cable, optical cable or mixed use). Cables usually use Aluminum conductors with insulation and one or more layers of plastic sheath. The cable usually consists of 2 to 3600 pairs. Large logarithmic cables are usually used in backbone cabling systems and are suitable for voice and low rate data transmission. The maximum lengths of these cables for trunk and horizontal (hub to desktop) cabling systems are specified in the latest GB 50311-2007. It should be noted that these maximum length limits apply to all media. They do not consider the impact of performance differences due to different cable types and protocol types used in the network. In fact, the maximum cable length will depend on the application of the system, the type of network and the quality of the cable.

Method of cable selection in generic cabling system

Since it is a building, it will definitely use a lot of communication cables. As the nervous system of intelligent building, generic cabling system is the key part and infrastructure of intelligent building. It has a very close relationship with the planning and design, construction, installation and maintenance of construction engineering. It is like an information superhighway in the building. People can communicate and communicate conveniently, quickly and effectively. It can be said that the generic cabling system connects the communication, computer and various facilities and equipment in the intelligent building to form a complete set of whole, so as to meet the requirements of highly intelligent.

But then we have to consider a problem: fire prevention. Once a fire breaks out in the building, the heat and gas released by these cables will become a major safety hazard. Looking at several large-scale fire accidents in China in recent years, many of them are due to the fact that the victims can’t escape. The burning of cables emits poisonous acid gas. In addition, a lot of heat and smoke are released from the combustion, which makes it difficult for the victims to breathe and lead to tragedies. Therefore, in addition to considering the performance, fire protection and environmental protection are also very important reference factors when we select cables for generic cabling system.

The global subsea power cable market will grow at a compound annual rate of over 4% from 2020 to 2024

The market for subsea power cables is expected to grow at a compound annual rate of more than 4 percent from 2020-2024, driven largely by surging demand for electricity, according to Technavio.

According to the report, 47 percent of the market growth in the forecast period will come from Europe, with Italy, Denmark and Finland being important markets for European subsea power cables.

Europe is the largest subsea power cable market in 2019, and government support and growing concern about wind power will significantly drive growth in the subsea power cable market in the region during the forecast period.

Offshore wind turbines can produce more energy using fewer turbines than conventional ones. As a result, the Asia-Pacific region will enjoy rapid growth during the forecast period. Thanks to heavy investment in offshore wind projects over the past few years, China and India will account for most of the region’s share of the forecast period.

According to the IEA, demand for electricity will rise by 40 per cent by 2024. Similarly, growing environmental concerns will force economies to use renewable energy to generate electricity. As a result, the number of renewable projects such as wind and tidal power projects is increasing in most countries, which in turn will increase the demand for undersea power cables or submarine cables. The growing demand for intercountry and island connections will be one of the main drivers of market growth. Subsea power grid interconnection projects in France – UK, Belgium – UK and Ireland – UK are under construction.

On the other hand, the growing demand for high-voltage direct current (HVDC) power cables will also drive the market growth. These HVDC cables are more and more popular compared with traditional cables because they are safe and reliable and can transmit power over long distances. These factors will drive the global subsea power cable market to grow at a compound annual rate of over 4% over the forecast period.

From the manufacturers’ point of view, Prysman, Nexans, Sumitomo Electric, Lenny Cable, Ankart Cable, Tengura Cable, Guhe Electrician, LS cable will continue to dominate the global subsea power cable market in the forecast period.

What is AAC cable ?

AAC cable products have been in the western market for many years, largely because the company needs cheap cables in order to save money. Because aluminum costs less than copper, AAC cables are ge detecty cheaper than all copper products. As a result, many buyers with tight budgets will look for cheaper and more cost-effective cable products. They may not realize that what they are receiving is substandard solid copper cables

It’s not hard for communication wholesalers and distributors to find these products on the Internet. Frank peri, executive director of AAAC, said the organization provides best practices and important information related to high-quality communication cables, connection equipment and related products. Suppliers provide non-standard cable products at a significantly lower price than standard products. Some suppliers sell both standard and non-standard cables. Pei pointed out that some industries and applications approve and are suitable for using AAC, but what we need to solve is the situation that is not suitable for using AAC cable.