Transformer Design Help

Discussion in 'General Electronics Chat' started by willheg, Oct 6, 2008.

  1. willheg

    Thread Starter New Member

    Oct 5, 2008
    1
    0
    hello there people, sorry if this is posted in the worng place but didn't really know where to start.

    i am currently in the poscess of building a machine and require a power suppy

    i live in new zealand and the mains is 240v 50Hz

    i am looking at running 4 stepper motors at 36vdc but each one is 4.2Amps and also another motor to run at 36vdc but it's rated at 12 amps

    i've looked at trying to wind my own transformer but cannot seam to find all the information that i need like how to work out the size on the E-I iorn cores

    i brought a book the other day on how to wind your own transformers with good help in that but i'm still lost on how to work out the above information.

    if anyone could help me with sites or recommened ways to get the power i'm looking at that would be great

    one other point is that the 36vdc 12 amp motor will handel 48volts
    and the 4 steppers will handel from 18 to 60 vdc but i'm just looking to run them all at 36vdc cheers
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    willheg,

    For the amount of work that it will take to wind a transformer and the support circuitry, it is better to purchase a supply. You do not need a linearily-derived supply, a switcher will due in your application because you are driving stepper motors.

    I'm assuming you are current chopping the steppers. In that case, you should be running higher voltage. If you have higher voltage, you can build up current faster in the windings; thus, achieving better dynamic performance. If these are low-impedance designed steppers, then you don't need to worry about it that much.

    You can use two of these supplies

    http://cgi.ebay.com/400W-36V-11A-Sw...Item?_trksid=p3286.m20.l1116#ebayphotohosting

    Or, take a look around Ebay for more appropriate supplies. These would have to run independently (one per two stepper drivers), don't try to run them in parallel. In the past, I had similar requirements for a CNC machine I built. I used brushless servos instead, but I needed a 1.2KW supply at 50V. I found an Astec supply off of ebay for 95$.. If I had built it, it would have cost me 2-3 times that.

    Steve
     
  3. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Here we go, the perfect supply!

    http://cgi.ebay.com/Astec-MP1-Regul...39:1|66:2|65:12|240:1318&_trksid=p3286.c0.m14

    Astec makes good stuff. It's 38.5V @ 25A! I have two of these that have undergone signficant duty and are still running great. You can finely adjust voltage by ~5-10% from nominal. They have overload protection, fans, etc.

    And for 45$ buy it now, it's cheaper than the magnet wire you would have used to wind the transformer.

    Steve
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Shipping charges from Ohio to New Zealand might cancel any eBay savings...
     
  5. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    If you live in Australia/New Zealand, you have to pay high shipping charges. If you live in Belgium, you are blessed with fine beers and chocolates. C'est la vie!

    Steve

    P.S.- There are services for international customers where you can ship the packages to, they will handle the customs for you and ship it to you.
     
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