Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Three phase supply

  1. Jan 3, 2015 #1
    we talk about three phase supply .. I want to know that what actually is three phase..?? Its obvious there are three wires carrying current but what is "phase" ?
    Is there something like, transmission line is further divided into three wires ..?? Please explain..its quite basic.. and I am confused..!!
  2. jcsd
  3. Jan 3, 2015 #2


    User Avatar
    Gold Member

    You are right that it is quite basic and a simple Google search should turn up a good explanation with diagrams. Basically, it means exactly what it says ... there are three phases of voltages supplied, 120 degrees from each other.
  4. Jan 3, 2015 #3
    the article above should help.
  5. Jan 3, 2015 #4
  6. Jan 4, 2015 #5
    The phase means the angular difference between the sinusoidal voltage on one wire to another. For three phase, the angular difference would be 360/3 = 120 deg. Instead of having three independent single phase transmission system which require (phase + neutral wire for each phase) 2*3 = 6 wires, if we go for three phase system with angular displacement of 120 deg we need only (1 wire for each phase and 1 common neutral) 3+1 = 4 wires for the same power transmission.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook