Submarine Power Cables: Design, Installation, Repair, Environmental Aspects (Power Systems)

The British government had obvious uses for the cables in maintaining administrative communications with governors throughout its empire, as well as in engaging other nations diplomatically and communicating with its military units in wartime. The geographic location of British territory was also an advantage as it included both Ireland on the east side of the Atlantic Ocean and Newfoundland in North America on the west side, making for the shortest route across the ocean, which reduced costs significantly.

A few facts put this dominance of the industry in perspective. In , there were thirty cable laying ships in the world and twenty-four of them were owned by British companies. In , British companies owned and operated two-thirds of the world's cables and by , their share was still Throughout the s and s, British cable expanded eastward, into the Mediterranean Sea and the Indian Ocean.

In , these four companies were combined to form the mammoth globe-spanning Eastern Telegraph Company , owned by John Pender. The first trans-pacific cables providing telegraph service were completed in —03, linking the US mainland to Hawaii in and Guam to the Philippines in Japan was connected into the system in The first trans-pacific telephone cable was laid from Hawaii to Japan in , with an extension from Guam to The Philippines. In , the North Pacific Cable system was the first regenerative repeatered system to completely cross the Pacific from the US mainland to Japan.

Transatlantic cables of the 19th century consisted of an outer layer of iron and later steel wire, wrapping India rubber, wrapping gutta-percha , which surrounded a multi-stranded copper wire at the core. The portions closest to each shore landing had additional protective armor wires. Gutta-percha, a natural polymer similar to rubber, had nearly ideal properties for insulating submarine cables, with the exception of a rather high dielectric constant which made cable capacitance high.

Gutta-percha was not replaced as a cable insulation until polyethylene was introduced in the s. In the s, the American military experimented with rubber-insulated cables as an alternative to gutta-percha, since American interests controlled significant supplies of rubber but did not have easy access to gutta-percha manufacturers.

The development by John T. Blake of deproteinized rubber improved the impermeability of cables to water. Early long-distance submarine telegraph cables exhibited formidable electrical problems. Unlike modern cables, the technology of the 19th century did not allow for in-line repeater amplifiers in the cable. Large voltages were used to attempt to overcome the electrical resistance of their tremendous length but the cables' distributed capacitance and inductance combined to distort the telegraph pulses in the line, reducing the cable's bandwidth , severely limiting the data rate for telegraph operation to 10—12 words per minute.

As early as , Francis Ronalds had observed that electric signals were retarded in passing through an insulated wire or core laid underground, and outlined the cause to be induction, using the analogy of a long Leyden jar. Michael Faraday showed that the effect was caused by capacitance between the wire and the earth or water surrounding it. Faraday had noticed that when a wire is charged from a battery for example when pressing a telegraph key , the electric charge in the wire induces an opposite charge in the water as it travels along.

In , Faraday described this effect in what is now referred to as Faraday's law of induction.

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As the two charges attract each other, the exciting charge is retarded. The core acts as a capacitor distributed along the length of the cable which, coupled with the resistance and inductance of the cable, limits the speed at which a signal travels through the conductor of the cable. Early cable designs failed to analyze these effects correctly. Whitehouse had dismissed the problems and insisted that a transatlantic cable was feasible.

Submarine communications cable

When he subsequently became electrician of the Atlantic Telegraph Company , he became involved in a public dispute with William Thomson. Whitehouse believed that, with enough voltage, any cable could be driven. Because of the excessive voltages recommended by Whitehouse, Cyrus West Field's first transatlantic cable never worked reliably, and eventually short circuited to the ocean when Whitehouse increased the voltage beyond the cable design limit.

Thomson designed a complex electric-field generator that minimized current by resonating the cable, and a sensitive light-beam mirror galvanometer for detecting the faint telegraph signals. Thomson became wealthy on the royalties of these, and several related inventions. Thomson was elevated to Lord Kelvin for his contributions in this area, chiefly an accurate mathematical model of the cable, which permitted design of the equipment for accurate telegraphy.

The effects of atmospheric electricity and the geomagnetic field on submarine cables also motivated many of the early polar expeditions.

Submarine communications cable - Wikipedia

Thomson had produced a mathematical analysis of propagation of electrical signals into telegraph cables based on their capacitance and resistance, but since long submarine cables operated at slow rates, he did not include the effects of inductance. By the s, Oliver Heaviside had produced the modern general form of the telegrapher's equations , which included the effects of inductance and which were essential to extending the theory of transmission lines to higher frequencies required for high-speed data and voice.

While laying a transatlantic telephone cable was seriously considered from the s, the technology required for economically feasible telecommunications was not developed until the s. A first attempt to lay a pupinized telephone cable failed in the early s due to the Great Depression. It was inaugurated on September 25, , initially carrying 36 telephone channels.

In the s, transoceanic cables were coaxial cables that transmitted frequency-multiplexed voiceband signals. A high voltage direct current on the inner conductor powered repeaters two-way amplifiers placed at intervals along the cable. The first-generation repeaters remain among the most reliable vacuum tube amplifiers ever designed. Many of these cables are still usable, but have been abandoned because their capacity is too small to be commercially viable.

Some have been used as scientific instruments to measure earthquake waves and other geomagnetic events. In the s, fiber optic cables were developed. The first transatlantic telephone cable to use optical fiber was TAT-8 , which went into operation in A fiber-optic cable comprises multiple pairs of fibers. Each pair has one fiber in each direction. TAT-8 had two operational pairs and one backup pair. Modern optical fiber repeaters use a solid-state optical amplifier , usually an Erbium-doped fiber amplifier. Each repeater contains separate equipment for each fiber.

These comprise signal reforming, error measurement and controls. A solid-state laser dispatches the signal into the next length of fiber. The solid-state laser excites a short length of doped fiber that itself acts as a laser amplifier.

As the light passes through the fiber, it is amplified. This system also permits wavelength-division multiplexing , which dramatically increases the capacity of the fiber. Repeaters are powered by a constant direct current passed down the conductor near the center of the cable, so all repeaters in a cable are in series.

Power feed equipment is installed at the terminal stations. Typically both ends share the current generation with one end providing a positive voltage and the other a negative voltage. A virtual earth point exists roughly halfway along the cable under normal operation. The amplifiers or repeaters derive their power from the potential difference across them. These included laboratories in the ships for splicing cable and testing its electrical properties.

Such field monitoring is important because the glass of fiber-optic cable is less malleable than the copper cable that had been formerly used. The ships are equipped with thrusters that increase maneuverability. This capability is important because fiber-optic cable must be laid straight from the stern another factor copper cable laying ships did not have to contend with.

Originally, submarine cables were simple point-to-point connections.

Submarine power cables : design, installation, repair, environmental aspects

With the development of submarine branching units SBUs , more than one destination could be served by a single cable system. Modern cable systems now usually have their fibers arranged in a self-healing ring to increase their redundancy, with the submarine sections following different paths on the ocean floor. One reason for this development was that the capacity of cable systems had become so large that it was not possible to completely backup a cable system with satellite capacity, so it became necessary to provide sufficient terrestrial back-up capability.

Not all telecommunications organizations wish to take advantage of this capability, so modern cable systems may have dual landing points in some countries where back-up capability is required and only single landing points in other countries where back-up capability is either not required, the capacity to the country is small enough to be backed up by other means, or having back-up is regarded as too expensive.

You already recently rated this item. Your rating has been recorded. Write a review Rate this item: Preview this item Preview this item. English View all editions and formats Summary: The demand for high-performance submarine power cables is increasing as more and more offshore wind parks are installed, and the national electric grids are interconnected. Submarine power cables are installed for the highest voltages and power to transport electric energy under the sea between islands, countries and even continents.

The installation and operation of submarine power cables is much different from land cables. Still, in most textbooks on electrical power systems, information on submarine cables is scarse.

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This book is closing the gap. Different species of submarine power cables and their application are explained. Students and electric engineers learn on the electric and mechanic properties of submarine cables. Project developers and utility managers will gain useful information on the necessary marine activities such as pre-laying survey, cable lay vessels, guard boats etc, for the submarine cable installation and repair.

Investors and decision makers will find an overview on environmental aspects of submarine power cables. A comprehensive reference list is given for those who want further reading. Allow this favorite library to be seen by others Keep this favorite library private. Find a copy in the library Finding libraries that hold this item Electronic books Additional Physical Format: Document, Internet resource Document Type: Thomas Worzyk Find more information about: Demand for high-performance submarine power cables is increasing, but information on them is scarce.

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