![]() ![]() A system using submarine power cables may be less costly overall if using high-voltage direct current transmission, especially on a long link where the capacitance of the cable would require too much additional charging current. High-voltage direct current transmission requires a converter at each end of a direct current line to interface to an alternating current grid. Most electrical power transmission systems use alternating current (AC), because transformers can easily change voltages as needed. Since the alternating magnetic field in AC cables causes losses in the armoring those cables are sometimes equipped with non-magnetic metallic materials (stainless steel, copper, brass). The armoring consists most often of steel wires, soaked in bitumen for corrosion protection. In three-core cables, three cable cores are laid-up in a spiral configuration before the armoring is applied. In single-core cables the core is surrounded by concentric armoring. In this stage the product is called cable core. The lead alloy is extruded onto the insulation in long lengths (over 50 km is possible). No other materials have been accepted so far. Mass-impregnated insulation can be used for massive HVDC cables up to 525 kV.Ĭables ≥ 52 kV are equipped with an extruded lead sheath to prevent water intrusion. ![]() Mass-impregnated cables have also a paper-lapped insulation but the impregnation compound is highly viscous and does not exit when the cable is damaged. A central oil channel in the conductor facilitates oil flow in cables up to 525 kV for when the cable gets warm but rarely used in submarine cables due to oil pollution risk with cable damage. The entire cable core is impregnated with a low- viscosity insulation fluid ( mineral oil or synthetic). ![]() Low-pressure oil-filled cables have an insulation lapped from paper strips. Certain formulations of XLPE insulation can also be used for DC. It is produced by extrusion, with an insulation thickness of up to about 30 mm 36 kV class cables have only 5.5 – 8 mm insulation thickness. Three different types of electric insulation around the conductor are mainly used today.Ĭross-linked polyethylene (XLPE) is used up to 420 kV system voltage. In some designs, profiled wires (keystone wires) are laid up to form a round conductor with very small interstices between the wires. The conductor can be stranded from individual round wires or can be a single solid wire. ![]() For voltages ≥ 12 kV the conductors are round so that the insulation is exposed to a uniform electric field gradient. Conductor sizes ≤ 1200 mm 2 are most common, but sizes ≥ 2400 mm 2 have been made occasionally. The conductor is made from copper or aluminum wires, the latter material having a small but increasing market share. for the connection of offshore wind turbines) often carry optical fibers for data transmission or temperature measurement, in addition to the electrical conductors. The electric core is a concentric assembly of inner conductor, electric insulation, and protective layers (resembling the design of a coaxial cable). The purpose of submarine power cables is the transport of electric current at high voltage. ( May 2022) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources in this section. This section needs additional citations for verification. ![]()
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