Submarine Power Cables
Submarine cables are wires wrapped with insulating and waterproof materials and laid underwater on the seabed and rivers for power or communication transmission. The role of submarine cables is to provide communication and power transmission for offshore wind power, offshore drilling platforms, island grid interconnection, land island interconnection, and other offshore projects.
ZMS submarine power cable company has studied the production of submarine cables for many years. Whether from submarine environment exploration, marine physical investigation, and the world’s large projects’ case study. We also apply sophisticated cable design, manufacturing, and installation methods. The excellent performance and service life of our submarine cables are guaranteed.
More Submarine Power Cable Products
Underwater submarine cables can be divided into submarine communication cables and submarine power cables according to their uses. Submarine power cable is mainly used for underwater transmission of high-power electricity. It is equivalent to the role of underground power cables, but the difference is the application of the occasion and the way of laying.
HVAC (High Voltage Alternative Current) Submarine Cable
HVDC (High Voltage Direct Current) Submarine Cable
The basic structure of submarine cable is conductor, insulation, metal shield, metal layer and sheath, filling, armored, composite fiber, auxiliary materials, etc.
— Conductor: for carrying current, usually composed of copper or aluminum.
— Insulation: provides an effective barrier to the extremely high potential difference between the inner and outer potential surfaces, and the commonly used material is now cross-linked polyethylene (XLPE).
— Water barrier sheath: protects the insulation from damage caused by moisture intrusion and maintains the strength of the insulation.
— Armor: Provides mechanical protection and tension stability, and is an important structural element.
— The outer cloak: is used to protect the submarine cable armor during transportation and deep burial installation, usually polypropylene rope (PP rope).
Submarine cable is mainly used underwater, in addition to the need to meet the basic electrical properties, water resistance, mechanical properties also have higher requirements.
Types of Submarine Power Cables
The types of submarine cables can be divided into three-core submarine cables and single-core submarine cables by structure. Most of the low- and medium-voltage lines use three-core submarine cables, and most of the high-voltage lines use single-core submarine cables.
The load type is divided into HVDC submarine cable and HVAC submarine cable.
HVAC submarine cable is characterized by large losses, but the operation and maintenance technology is mature, supporting small construction costs.
HVDC submarine cable is characterized by small losses, and easy to achieve long-distance transmission of electricity. DC cable in the transmission capacity, loss, length, and stability performance is better than the AC cable. But the DC cable supporting the construction costs are high.
Therefore, designers of submarine cable lines usually have to make technical and economic trade-offs to choose the right type of cable. To achieve maximum benefits.
Submarine Cable Structure Types
Submarine cable development so far, the structure design to make a variety of exploration and experimentation, the main structure includes the following types:
- 1. Impregnated paper-covered submarine cable. Suitable for not more than 45kV AC and not more than 400kV DC lines. At present, it is only installed in a water depth of 500m or less.
- 2. Oil-filled submarine cable. Use the method of supplemental impregnant to eliminate the air gap in the cable. When the cable temperature rises, the impregnant expands, the pressure inside the cable increases, and the impregnant flows into the oil supply tank. When the cable cools, the impregnant shrinks, the pressure inside the cable decreases, and the impregnant in the oil supply tank flow into the cable again, preventing the generation of air gaps. So it can be used for 110 kV and above lines. Laying in water depth up to 500m.
- 3. Inflatable (pressure-assisted) submarine cable. The use of impregnated paper bags of inflatable cable than oil-filled cable is more suitable for the longer submarine cable network. But because of the need to operate under deep water using high air pressure, thus increasing the difficulty of designing the cable and its accessories, generally limited to a water depth of 300m.
- 4. "Oil pressure" tube submarine cable. Only suitable for several kilometers of the cable system, because the very long cable to pull into the pipe, is subject to great mechanical constraints.
- 5. Extruded insulation (cross-linked polyethylene insulation, ethylene-propylene rubber insulation) cables. Suitable for up to 200kV AC voltage. Ethylene propylene rubber is more resistant to dendritic phenomena and local leakage than polyethylene, making submarine cables function more effectively.
Brief Description Of The Manufacturing Process Of Submarine Power Cables
The entire manufacturing process of the submarine power cable is basically the same as the general power cable.
But there are special requirements for the mechanical strength and corrosion resistance of the sea cable. And the length of the undersea cable is required to be extended as much as possible.
The following is a brief description of the manufacturing process of impregnated paper cables and extruded insulated submarine cables.
Impregnated paper cable is first wrapped with insulating paper core, followed by vacuum drying, oil dipping, after completing the conductor core, and then wrapped with lead sheath, which is subject to the process of continuous extrusion.
Extrusion of extremely long cable cores is an extremely important step and must be carried out night and day. The conductor core of the oil-filled cable passes through a siphon transport tube from the storage cylinder to the lead press. And the tube is filled with degassing oil, which flows in the opposite direction to the conductor core in order to isolate the contact between the core and the air.
After the core is covered with lead, it is coiled on a rotating platform (if the cable is oil-filled or inflatable, the appropriate amount of metal reinforcement can be added). Then the underwater cable is covered with a polyethylene sheath (extruded polyethylene sheath is also a continuous operation). And then wrapped with two layers of galvanized steel wire armor, covered with oiled hemp impregnation.
In the subsequent production process, the lead sheath and metal strip must be grounded through the polyethylene sheath at the appropriate stage.
Most of the production processes for cross-linked polyethylene cables and ethylene-propylene rubber insulated submarine cables are similar to those for paper-insulated lead-sheathed cables, except for the extrusion and vulcanization of the synthetic rubber insulation. But without the use of a lead sheath.
Compared With Underground Cables, Submarine Cables Have Many Advantages
First, laying does not need to dig a trench or support with brackets, thus less investment, and faster construction.
Second, in addition to the landing lot, the deepest submarine wire cable is mostly in a certain test of the seabed, not subject to the destruction of the natural environment such as wind and waves and interference from human production activities.
Therefore, the submarine line is safe and stable, with strong anti-interference ability and good confidentiality performance.
Prospects Of ZMS Submarine Cables
The complexity of the marine environment of the submarine cable project put forward high requirements, underwater cable engineering is a recognized problem in the world, construction difficulties, high maintenance costs. And it was only a few companies in the world have the ability to lay and commission submarine high-voltage cable. The development of the submarine cable market has been greatly restricted. More issues, but more solutions to the problem. In the future, the application space of submarine cable will be broader, it is important infrastructure equipment, and is an important technical support for human beings to achieve the effective expansion of their own activity area. It transports clean ocean energy to the mainland, relieving the tension of mainland resources, and also transports mainland energy to the ocean, contributing to the development of the ocean economy.
ZMS Submarine Cable company firmly believes in this. Therefore, we strictly require ourselves. Managed with high-quality products and after-sales service, ZMS cable has a strong technical force, exquisite technology, advanced production equipment, complete testing means, and advanced enterprise management.
The submarine cable products produced by ZMS cable factory include submarine power cables, submarine communication cables, submarine fiber optic cables, underwater cables, Internet cables in the ocean, and other products. A variety of new products have been researched and independently judged, taking into account the comprehensive factors of equipment, materials, yield, conversion efficiency, quality and cost, and the need to master the right timing for production. For the mainstream technology direction, the company has reserved for mass production and will launch differentiated products according to the characteristics of different markets.
In recent years, through independent research and development, the company has been breaking through the length and voltage level of underwater cable production and taking the lead in the development of dynamic submarine cable, towing cable, and other special submarine cables. The production of submarine cable-related products are widely used in marine scientific research and resource development and other fields, to provide assistance to the construction of China’s “Ocean Power” strategy.
