Design and laying of submarine cable

The design of submarine optical cable: anti-corrosion, anti-seepage, but also against sharks, compared with coaxial cable, optical fiber is quite obvious advantages, but its own is quite fragile, so this protection of optical fiber submarine cable peripheral protection structure put forward higher requirements. Specifically, the design of submarine optical cable must ensure that the internal optical fiber is not affected by external forces and the environment. Its basic requirements include adaptability to submarine pressure, abrasion resistance and non-corrosion, etc. It also has to prevent hydrogen from forming inside (and therefore not using aluminum) and hydrogen from outside (preventing gas infiltration). In addition, it must be properly armored to protect it from trawlers, anchors and sharks. When the cable is broken, but also as much as possible to reduce the length of seawater into the cable; At the same time, it can withstand the tension during laying and recovery; Last but not least, the service life of submarine cables is generally required to be over 25 years.

Based on the above requirements, the current design structure of submarine cables usually consists of one or two coating treatments of the fiber in a spiral wrapping around the center, and then reinforcing members (made of steel wire) wrapped around (usually 69 mm in diameter). Specifically, it includes: polyethylene layer, polyester resin or asphalt layer, steel strand layer, aluminum waterproof layer, polycarbonate layer, copper or aluminum tube, paraffin layer, alkane layer, fiber bundle, etc.

Laying process: from relying on the tide to relying on robots

The laying project of submarine optical cable is recognized as one of the most complicated and difficult large-scale projects in the world, which is not difficult to understand why the service life of submarine optical cable is required to reach more than 25 years, because laying once is very troublesome! The laying process of submarine optical cable can be divided into two parts, namely, the laying of shallow sea area and the laying of deep sea area. In the deep sea area, the laying of submarine optical cable has to go through three stages, namely, exploration and cleaning, sea cable laying and burial protection. The laying of submarine cables mainly depends on the cable laying ships and underwater robots. The cable laying ships should pay special attention to the sailing speed and cable release speed, so as to control the water inlet Angle and laying tension of the cable, so as to avoid damaging the fragile optical fibers in the cable due to too small bending radius or too large tension.

As shown in the figure above, this is the laying process of an undersea optical cable. In shallow sea areas, the laying ship stays a few kilometers away from the coast, and the cable placed on the floating bag is pulled to the shore by the shore tractor. Then the floating bag is removed to make the cable sink to the sea floor. In the deep sea, the laying ship is mainly responsible for releasing optical cables, and then the underwater detector is combined with the underwater remote control vehicle for underwater monitoring and adjustment, so as to avoid uneven and rocky areas on the seabed. The robot then proceeded to a three-step operation: first, it created a trench about 2m deep in the sea floor, using high-pressure flushing; The second step is to put the cable into the trench; Third, cover it with the sand nearby.

Special to note here is that a intercontinental submarine cable is difficult to a complete laid, because at present the most advanced optical cable laying ship can only carry 2000 kilometers of fiber optic cable (and now laying rate can only reach 200 km/day), thus laid to segments, and each paragraph “cable docking”, needs to be done in laying the ship, and requires high technology.

Demand is down and the electricity market favours renewables

The COVID-19 pandemic shows the power market’s preference for renewables in the face of falling demand, and the clean energy transition is likely to accelerate, Moody’s reports.

“Coal generation has continued to decline, while renewable energy has shown greater resilience in key markets in the United States, Europe, China and India,” the report said.

As a result of the blockade, electricity demand in India has fallen by 20 per cent, which has had a significant impact on coal production.

Both business and household electricity demand are expected to be severely affected by the recession and weaker expectations for long-term growth. Conventional energy production, such as coal and oil, also declined, the agency said.

Worldwide, renewable energy accounts for most of the recent new capacity, which continues to displace coal-fired power. Moody’s said the trend was expected to continue as electricity demand fell sharply as a result of the blockade.

“Covid-19 could have a ratchet effect, limiting any rebound in coal production and accelerating declines in the US and Europe for several years,” the rating agency said.

Moody’s also predicts that increased use of biofuels, electric cars and improved engine efficiency will increase the likelihood that oil demand will flow over time. While most developed countries already have targets and incentives for rapid adoption of electric vehicles over the next decade, India has yet to enact such a policy.

Renewable energy growth hit a record high in 2019

On June 17, the 69th edition of THE BP Statistical Yearbook on World Energy was released. The Yearbook points to continued strong growth in renewable energy. Renewable energy, led by wind and solar, is growing at record levels, accounting for more than 40% of primary energy growth in 2019. Meanwhile, coal consumption has fallen for the fourth time in the past six years, and its share of the global energy mix has fallen to its lowest level in 16 years.

But the structural picture remains grim. Although coal’s share fell last year, it is still the biggest source of electricity, accounting for more than 36% of global output. Renewables, by contrast, account for only 10 per cent, and will need to grow even more strongly over the next three decades to decarbonise the sector.

More worrying is the trend in carbon emissions. Carbon emissions growth slowed to 0.5% in 2019, a lower rate that suggests some optimism. But this deceleration comes against the backdrop of a huge 2.1 per cent increase in carbon emissions in 2018. As the world emerges from the coVID-19 crisis, the energy transition will also require decisive changes towards a more sustainable path.

To achieve net zero emissions by 2050, the world would need to reduce carbon emissions by the same amount every other year for the next 25 years, or 2.6 billion tonnes, the yearbook says.

This can only be achieved through a fundamental shift in behaviour, namely through more efficient use of resources and energy, and the implementation of all the technologies that are available in zero and low carbon energy, including renewable energy, electrification, hydrogen, CCUS (carbon capture and storage), bioenergy, and more.

In terms of consumption, China has become the largest contributor to global energy consumption growth, accounting for more than three quarters of global net growth. In the net zero vision, China’s energy policy choices and paths will directly affect the future pattern of global energy consumption.

The difference between photovoltaic cable and ordinary cable

The characteristic of photovoltaic cable is determined by its special insulating material and sheath material, which is called cross-linked PE. After irradiation by the irradiation accelerator, the molecular structure of the cable material will change, thus providing its performance in all aspects.


Photovoltaic cables are often exposed to sunlight, and solar systems are often used under harsh environmental conditions, such as high temperatures and ultraviolet radiation. In Europe, sunny days will result in solar system site temperatures of up to 100°C. At present, we can use all kinds of material with PVC, rubber, TPE and cross-linked with high quality material, but unfortunately, the rated temperature of 90 ° C rubber cable, and even the temperature of 70 ° C rated PVC cable is also often used outdoors, the national golden sun project horse, there are many contractors in order to save costs, not to choose cable specially used for solar system, choosing instead to replace the ordinary PVC cable photovoltaic cable, obviously, this will greatly affect the service life of the system.
The characteristic of photovoltaic cable is determined by its special insulating material and sheath material, which is called cross-linked PE. After irradiation by the irradiation accelerator, the molecular structure of the cable material will change, thus providing its performance in all aspects.


Mechanical load resistance:
In fact, during installation and maintenance, cables may be wired along sharp edges of the roof structure and subjected to pressure, bending, tension, cross-tensile loads and strong shocks. If the cable sheath is not strong enough, the insulation layer of the cable will be seriously damaged, which will affect the service life of the whole cable, or lead to problems such as short circuit, fire and personal injury risk.

What is aluminium alloy power cable?

Aluminum alloy power cable is a new material power cable with AA8030 series aluminum alloy material as the conductor, adopting advanced technology such as special roll forming wire twisted production process and annealing treatment. Alloy power cable made up for the inadequacy of previous pure aluminium cable, although there is no improve the conductive properties of the cable, but the bending performance, creep resistance and corrosion resistance are greatly improved, to ensure that the cable for a long time to keep continuous stable performance when overload and overheat, the AA – 8030 series of aluminum alloy conductor, which can greatly improve the conductivity of the aluminum alloy cable, high temperature resistance, and solves the problem such as pure aluminium conductor, creep. The conductivity of aluminum alloy is 61.8% of that of copper IACS, the most common reference material. But at the same volume, the actual weight of an aluminum alloy is about a third that of copper. Therefore, the weight of the aluminum cable is about half that of the copper cable with the same load flow. The use of aluminum cable instead of copper cable can reduce the weight of the cable, reduce installation costs, reduce equipment and cable wear, making installation easier.
Aluminum alloy cables add copper, iron, magnesium, silicon, zinc, boron and other alloying elements into the electrical aluminum. At the same time, through process adjustment, the mechanical properties of aluminum alloy conductors are greatly improved to avoid the problems of low elongation, poor creep resistance and poor flexibility of pure aluminum conductors and increase the connection reliability of the cable system. In addition, keep the electrical properties of aluminum alloy and electrical aluminum conductor equal, at 61%IACS above.
Alloy power cable made up for the inadequacy of previous pure aluminium cable, although there is no improve the conductive properties of the cable, but the bending performance, creep resistance and corrosion resistance are greatly improved, to ensure that the cable for a long time to keep continuous stable performance when overload and overheat, the AA – 8030 series of aluminum alloy conductor, can significantly improve the conductivity of the aluminum alloy cable, high temperature resistance, at the same time solve the pure aluminium conductor electrochemical corrosion, creep, etc.
The conductivity of aluminum alloy is 61.8% of that of copper IACS, the most common reference material. But at the same volume, the actual weight of an aluminum alloy is about a third that of copper. . Therefore, the weight of the aluminum cable is about half that of the copper cable with the same load flow. The use of aluminum cable instead of copper cable can reduce the weight of the cable, reduce installation costs, reduce equipment and cable wear, making installation easier.
Aluminum alloy power cable has good mechanical properties and electric properties, it can be widely used various fields of national economy, such as common people residence, high-rise buildings, elevators, both large supermarket shopping malls, subway, airport, railway stations, hospitals, Banks, office buildings, hotels, postal telecommunications building, exhibition hall, library, museum, ancient buildings, schools, electricity, building, public places of entertainment, tunnels, underground buildings, warehouses, etc., can also be used for metallurgy, steel, coke, coal mines, power plants, power transmission and transformation station, shipbuilding, petroleum, chemical, aerospace, military, medicine, nuclear power plants, paper and other industries, And home appliances, cars, public transportation, and so on.

High temperature superconducting cable

High temperature superconducting cable is a kind of power facility that adopts unimpeded superconducting material that can transmit high current density as the conductor and can transmit large current. It has the advantages of small volume, light weight, low loss and large transmission capacity, and can realize low loss, high efficiency and large capacity transmission. HTS cables will first be used for short distance power transmission (e.g., generator to transformer, substation to substation, underground substation to urban grid port) and short distance power transmission of large current, such as electroplate plant, power plant and substation, as well as large or super-large city power transmission.

The transmission loss of HTS cables is only 0.5% of the transmission power, much lower than the 5-8% loss of conventional cables. Under the same weight and size, compared with the conventional power cable, the capacity of HTS cable can be increased by 3-5 times and the loss reduced by 60%, which can obviously save the occupied area and space and precious land resources. Retrofitting existing underground cable systems with HTS cables would not only increase transmission capacity by more than three times, but also reduce total costs by 20%. The use of HTS cable can also change the traditional transmission mode, using low voltage and high current to transmit electric energy. Therefore, HTS cable can greatly reduce the loss of power system, improve the total efficiency of power system, and have considerable economic benefits.

The global market for superconducting applications is forecast to reach $244 billion (1516.4 billion yuan) by 2020, with HTS cables accounting for about 5 percent of the total. The world’s existing underground cables with a total length of about 130,000 kilometers will probably be replaced by HTS power cables. Therefore, the market prospect of HTS cable is very broad.

Cable raw material copper, trend analysis in July

Analysis of the main products of cable raw materials (copper): According to the monitoring data of the cable network, the domestic spot copper price continued to fall sharply in July, and the overall copper price fell during the month. The average spot copper price in the beginning of the month was 42585. RMB/ton, the average spot copper price at the end of the month was 39,030 yuan/ton, and the price dropped by 3555 yuan/ton, a decrease of about 8.35%.

Macroscopically, abroad, the minutes of the Federal Reserve’s June meeting announced recently confirmed the recovery of the US economy. The Federal Reserve’s interest rate hike in September may intensify. This topic may still be the focus of the market in August. However, the US GDP in the second quarter fell short of expectations. It was not easy to realize the interest rate hike in September. What is more certain is that the strength of the US dollar will not change, which may trigger a new round of upsurge of funds leaving the commodity market, which will also put pressure on copper prices. On the domestic front, the current Chinese economy is still operating at a low level. Although the Chinese government continues to introduce loose monetary policy in the second half of the year, it has limited room for short-term boost to the real economy. Therefore, the copper market may still be under pressure in the first half of August. When the off-peak season alternates, copper prices may rebound.

Market: Since the second quarter, the downstream operating rate has gradually increased, and through the arrival of the peak season of copper pipes and other industries, the overall market turnover has improved, but year by year, this year’s peak season is not busy. Affected by the weakening of consumption in the off-season in July and the weakness of China’s economy, spot copper prices have dropped sharply, but merchants’ adjustments have remained stable and no selling has been seen. After the copper price hit a new low, suppliers are reluctant to sell. When copper supply has shrunk, consumption has shrunk, and the overall economy is severely severe, copper prices are unable to rebound, and the subsequent continued decline may break through.

Inventory: LME and Shanghai copper inventories continued to show a slight growth trend this month. The latest statistical data shows that LME copper stocks reported 345,475 tons, which is a bit higher than before; while in the past week, Shanghai copper stocks on the Shanghai Futures Exchange increased slightly to 103,117 tons. Inventory has been in a downward channel for several months, but it increased slightly in July. The growth in July may be related to the recent cross-market arbitrage. Due to the continued profitability of imports, the positive arbitrage of buying LME copper and selling Shanghai copper has the opportunity. This may attract some traders to ship the goods to the warehouse, but the overall amount of change is not large. . At present, the overall supply pressure of copper is not great, and the difficulty of copper price upwards still comes from the shrinkage of the demand side.cable cu

Outlook forecast: July economic indicators have been significantly eased compared to the previous month, but the market focus has remained on the economic side. The recent US data has been weak and unfavorable, but the dollar is still strong, putting pressure on basic metals such as copper, plus China Copper consumption has always been in a weak position, which has greatly reduced global copper consumption. Therefore, copper prices have been unable to rebound and have fallen frequently. In the short term, there is still room for rebound in copper prices, but in the long run, US interest rate hikes have reached the long-term strength of the US dollar index, coupled with the copper market demand has not yet recovered significantly, copper prices will weaken again later.

What is the basic structure of the cable?

One is the conductor structure.The conductor of cable is usually made of high purity copper or aluminum of certain toughness and strength with good electrical conductivity. Conductor sections are commonly used in circles and sectors. A conductor with a smaller section (less than 16 square meters) is made of a single copper wire, while a conductor with a larger section (16 square meters or more) is made of several copper wires twisted in fractional layers. When twisted, the twisted direction of the two adjacent layers is opposite.Cable structure


The second is the insulation layer of the cable.The insulation layer of cable is used to make the multi-core conductor and conductor and sheath mutually isolated, and to ensure a certain electrical compressive strength, it should have a certain heat resistance and stable insulation quality.
The thickness of the insulating layer is related to the working voltage. Generally speaking, the higher the voltage level is, the thicker the insulation layer will be, but not in direct proportion.Cable structure


Third, cable sheath.So that the cable insulation is not damaged, and to meet the requirements of various use conditions and environment, divided into inner sheath and outer sheath.Inner sheath is a protective covering covering the cable insulation to prevent the insulation from being affected by moisture, mechanical damage, light and chemical corrosive media, etc., and can also flow through short-circuit current. Common inner protective layer has non-metallic polyethylene sheath, polyvinyl chloride sheath, metal corrugated aluminum sheath and so on.Outer sheath is the protective covering layer outside the inner sheath of the cable, which mainly plays the role of mechanical strengthening and anti-corrosion. The outer sheath is usually composed of metal tape armor or wire armor plus polyvinyl chloride or polyethylene sheath.Cable structure

If there are related problems, we can communicate with each other.

What are the advantages of environmental friendly cables?

What are the advantages of environmentally friendly cables compared to other traditional cables? Compared with ordinary cables, environmentally friendly cables have the following advantages:

The first is to have high flame retardancy. We all know that the flame retardant performance of the cable is very important. It fully ensures the safety and fire resistance of the cable. The cable is not easy to burn and catch fire, and can prevent the flame from expanding.

The second is halogen free, green insulation, special oxygen barrier material, not only has good electrical performance, mechanical properties, and to ensure that the product does not contain halogen, to prevent the formation of traditional PVC wire burning in the combustion process to produce cancer-causing dioxins British materials to prevent secondary pollution.

The third is a new environment-friendly coated wire and cable material that is free of odor and corrosive odor, does not contain hydrochloric acid and other toxic gases, and produces no pollution to the environment. It will not produce or emit very little during the use and combustion. Acidic gas, to ensure the safety of personnel and reduce environmental protection features such as equipment damage.

The fourth one is high light transmittance. The smoke produced by burning environmentally friendly cables is very thin, which is helpful for evacuation and fire fighting. The light transmittance of the product is greater than 40%, much higher than that of the traditional flame-retardant cable and the light transmittance is lower than 20% or even higher.

The last one is the environmental protection type cable waterproof and ultraviolet protection performance, environmental protection type wire and cable special molecular structure, to ensure the production of ultra-low water absorption . Special ultraviolet absorber makes the product have good anti-ultraviolet performance。

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.