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Line voltages

  1. May 31, 2004 #1
    If I'm considering a 3 phase line (25kV line-to-line voltage) that comes to a point and splits into single phase lines, what is the line voltage of one of the single phase lines ?

    Does it remain 25 kV or is it 14.4 kV because you're only dealing with 1 phase and a neutral now ?

    Any explanation would be great

  2. jcsd
  3. Jun 1, 2004 #2
    Normally, they do not distribute L-N = Vl/sqrt(3)=14.4kV, only L-L =25kV. The phases can split AB, BC, CA. The single phase transformers convert 25K--> user voltage with the ground reference applied at the secondary neutral.
  4. Jun 28, 2004 #3
    A single phase line by definition is a circuit with only one phase. So you need a neutral side to create a loop. The voltage differential between the line and the neutral is, of course, +/- 14.4 kV and not 25 kV.

    If you use both line (AB, AC, or BC) ..... I don't think that a single phase line. It may be within the category of two phase line :-)

  5. Jun 28, 2004 #4
    For distribution purpose only line voltages preferred so neutral is not used. And 25KV will not be splitted into single phase directly it will be step downed and than you will get a sinle phase line. sinle phase line voltage depends on the transformer rating.
  6. Jul 4, 2004 #5
    Actually, The main method of urban and suburban over head and URD is done single phase with line-neutra *in the usa*, europe is 3-phase secondary distribution 3-phases+ 2*line voltage = 8* the secondary line distance over the US, the neutral designation is MGN, or multiple grounded neutral, It is a lower wire of the four, or sometimes used as a top wire overhead shield in lightning prone areas. the L-N is used as the final distribution to the LNL +120 N -120 final use in typical residential apps.
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