line voltage

Discussion in 'General Electronics Chat' started by matt11111, Jun 17, 2009.

  1. matt11111

    Thread Starter Member

    May 12, 2009
    11
    0
    I have done measurments on some three phase machines. I have measured the line to ground voltage while monitoring the line to ground current to determine things such as PF and starting current.

    Would I be right to assume that if I wanted the line to line voltage all I would do is multiply the line to ground voltage for a single phase by 2?

    Also, my panel says it is a 600v supply but when I measure from line to ground it gives a value of 350 v RMS. Multiplying by 2 to get the line to line voltage gives 700 v. Most of the machines are rated for 575v or 550v.
    Am I taking the measurement wrong? How can a panel rated for 600v handle 700v, and how can a machine that is rated for 575v (on the nameplate) be running on the higher 700v supply?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    This is not true.

    The line-line voltage is the line-ground voltage multiplied by the sqrt(3).
     
  3. alim

    Senior Member

    Dec 27, 2005
    113
    1
    Hi the line to line voltage called the line voltage is 1.732 times the phase voltage , conversely the phase voltage is 0.577 times the line voltage thus 600* 0.577equals 346.2 approx. 350v.
     
    fraz.kharal likes this.
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