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Wtshymanski (talk | contribs) wordy; we can take it everything about these things is "specially designed"; condense headings, not every paragraph needs a heading |
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=== Monopole ===
[[File:Hvdc monopolar schematic.svg|thumb|right| Block diagram of a monopole system with earth return]]
In a
If no metallic return conductor is installed, current flows in the
▲If no metallic conductor is installed, current flows in the [[Ground (electricity)|earth]] and/or [[sea]] between two specially designed earth electrodes. This arrangement is a type of [[single-wire earth return]] system.
The electrodes are usually located some tens of kilometres from the stations and are connected to the stations via a medium-voltage [[electrode line]]. The design of the electrodes themselves depends on whether they are located on land, on the shore or at sea. For the monopolar configuration with earth return, the earth current flow is unidirectional, which means that the design of one of the electrodes (the [[cathode]]) can be relatively simple, although the design of [[anode]] electrode is quite complex.
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* An unbalanced current path may result in a net magnetic field, which can affect magnetic [[navigation]]al [[compass]]es for ships passing over an underwater cable.
These effects can be eliminated with installation of a metallic return conductor between the two ends of the monopolar transmission line. Since one terminal of the converters is connected to earth, the return conductor need not be insulated for the full transmission voltage which makes it less costly than the high-voltage conductor. The decision of whether or not to use a metallic return conductor is based upon economic, technical and environmental factors.<ref>[http://www.rpdc.tas.gov.au/projects_state_signif/Basslink Basslink] project {{webarchive |url=https://web.archive.org/web/20030913224914/http://www.rpdc.tas.gov.au/projects_state_signif/Basslink |date=September 13, 2003 }}</ref>
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