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Three phase

I was working on a semi hermetic compressor Three phase and I noticed that each winding had two wires to it and it was connected to two different contactors why is that??
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  • Tom Blackwell_2
    Tom Blackwell_2 Member Posts: 126
    Part winding start

    The two windings are probably for part-wimding start to reduce the starting current.
  • Techman
    Techman Member Posts: 2,144
    edited March 2010
    three phase

    paul, was that each winding[3] has two wirers to it ,or,is it two set of  3 windings [3 phase] that  has three wirers  per [3] winding?If it is two seperate sets of 3phase windings then as Tom said it is a part wind start compressor. The first contactor energizes and gets the compressor moving and a timer brings the 2nd contactor on a second or two or three later bringing the comp upto full speed. It prevents a massive amperage draw by trying to start the comp with a single contactor. Heaven help you if you miswire the 2nd contactor and reverse the rotation of that set of windings.
  • HVAC_Journeyman
    HVAC_Journeyman Member Posts: 8
    Partial Winding Start

    Sounds like you were looking at a part winding start. 
  • ddlong1286@yahoo.com
    [email protected] Member Posts: 139
    What model

    What brand and model was it? Copeland electrical handbook has a good diagram for the wiring.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Tom B/ and Terry have it.

    Older Carrier and Chrysler systems also used this.  If you look at this same set up today, meaning the way it starts and runs,  Most simi's start unloaded and use either a electrical Bypass unloader, Hot gas unloader, or Suction unloader....And I'm sure the last one is incorrect since it's been a while/////////////  Techman, How the hech have you been?  Keeping busy?


    Mike T.
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