Single phase motor start problem

Discussion in 'General Electronics Chat' started by manmad, Aug 23, 2016.

  1. manmad

    Thread Starter New Member

    Aug 23, 2016
    2
    0
    hi members,

    i have purchased a rebar cutting machine from a china supplier and i am having lot of trouble with it.

    this is the diagram how i am connecting the machine, when i connect this way the capacitor is giving smoke
    [​IMG]


    Blue = Centrifugal switch
    Brown = main winding
    black = start winding
    red = run capacitor 40uf 450v
    Grey = start capacitor 300uf 250v
    IMAG0166.jpg

    one electric guy came to me and he told the capacitor UF is too low thats why its giving me smoke, and you have to find the right size of the capacitor, to do it use have to calculate the main winding of the motor
    image-0-02-01-02092085d8a47d3c71d64c83362d0daa6261c02397fd2200b2fa01e48fd421f6-V.jpg image-0-02-01-8c4a4fc3f0d1fcb06e82b256a14844545292a6829553705cb00aad6b40b7353a-V.jpg image-0-02-01-1add50b904abea7c697cbe9fb38dfb9ee37369cdb213cb0bdf44e4b3396f5aef-V_1.jpg image-0-02-01-1add50b904abea7c697cbe9fb38dfb9ee37369cdb213cb0bdf44e4b3396f5aef-V_1.jpg image-0-02-01-8c4a4fc3f0d1fcb06e82b256a14844545292a6829553705cb00aad6b40b7353a-V.jpg image-0-02-01-02092085d8a47d3c71d64c83362d0daa6261c02397fd2200b2fa01e48fd421f6-V.jpg
    can any one please help me how can i sole this problem?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    For one, if this was a new machine purchased from a supplier, how come you need to get involved in wiring the motor up?
    Chinese motor capacitors are notorious for very poor quality and early failure, hopefully the start cap you show is a a bi polar electrolytic and not a uni-polar?
    The start cap should be in series with the centrifugal switch.
    Max.
     
  3. manmad

    Thread Starter New Member

    Aug 23, 2016
    2
    0
    Thank you..

    This one is a newly purchased machine and in the picture is how i connected the cable.. i dont know why this happend and i am not a electrition.. the blue capacitor is giving the smoke.. can you give me a solution or you need more info
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    The 300μf cap can only be in circuit for a very brief time, a few seconds, the centrifugal switch should open the cap circuit so it is not under power for too long.
    Need more information on the motor terminal block connections and details from the supplier.
    I would have thought it would be supplied as a running M/C, why does it have to be wired?.
    This is a common problem with machines purchased without support, also the Chinese are very lax on N.A. regulations when it comes to code.
    Max.
     
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