1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A switch on 3-phase

  1. Jul 3, 2008 #1

    How do you switch a 3-phase circuit on and off? Is it possible to put a relay on just one leg of the phase, or do you need to somehow switch all 3 at the same time? In industry, what do they use to switch 3-phase circuits, for instance, with a push button start/stop?

  2. jcsd
  3. Jul 3, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    You definately need to switch all three at once.
    since three phase is generally used with failry beefy supplies you tend to have a controller switching them from an electronic switch rather than a simple mechanical switch.
  4. Jul 3, 2008 #3


    User Avatar
    Science Advisor

    A 3-phase relay or contactor: http://www.allaboutcircuits.com/vol_4/chpt_5/2.html

  5. Jul 3, 2008 #4


    User Avatar

    Staff: Mentor

    You weren't very specific, triden, but there are plenty of switches out there that are simply three single pole switches mechanically linked together. Any ordinary circuit breaker can have a peg inserted between it and its neighbors to make such a switch, for example. Larger ones are specially made with 3 poles, but function the same. You can get relatively ordinary circuit breakers probably up to a few thousand amps at a few thousand volts. Grainger stocks them up to 1000A at 600V.
    Last edited: Jul 3, 2008
  6. Jul 3, 2008 #5


    User Avatar
    Science Advisor
    Gold Member

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: A switch on 3-phase
  1. 3-phase systems (Replies: 13)

  2. 3 phase motor noise (Replies: 4)