High-voltage ac electrification at 50 or 60 Hz is much cheaper than the medium-voltage dc or low-frequency ac systems developed prior to 1950, but 20 years after 25 kV became the new standard the choice of voltage is once again a matter for debate. For a few years it looked as if 25 kV would continue as the world standard, but a challenge has come from 50 kV in the 1970s based mainly on reduced transmission line and substation costs. While offering some savings where heavy trains are run through empty country, 50 kV seems unlikely to displace 25 kV in general use because clearances must be greater and catenary design is more complex.

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  • Corporate Authors:

    IPC Transport Press, Limited

    Dorset House, Stamford Street
    London SE1 9LU,   England 
  • Authors:
    • Siemens, W H
  • Publication Date: 1978-4

Media Info

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Filing Info

  • Accession Number: 00178926
  • Record Type: Publication
  • Source Agency: British Railways
  • Files: TRIS
  • Created Date: Jul 29 1978 12:00AM