30A or five 6A dc power supplies

Discussion in 'The Projects Forum' started by fawcetteng, Jan 9, 2012.

  1. fawcetteng

    Thread Starter New Member

    Dec 11, 2010
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    0
    Would like some direction from the experts here! I'm an ME with a lot of hands on electrical work, but not a lot of electronics, so bear with me.

    my application is testing dc motors, 12v and 24v, mounted on a gearbox. I have five test stands and would like 12 and 24 v power at each. Maximum current would be 6a per station, although it never is this high.

    What would be the best (read most affordable) way to do this? Two larger 30A off-the-shelf power supplies at the end of the line, wired to each of the 5 local stations? Or individual units at each of the stations.

    I've read about dual secondary power transformers (stancor p-6379)which look like i can go from 120v down to 12 or 24 in one unit. but this would still be ac, right, and i'd need to rectify it. do i need a voltage regulator with these?

    you see how basic my knowledge is. thanks for the help.
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    945
    Regardless of the details of your project, I see one choice would disable all of your test stations should it suffer a 'fault', while the other choice would keep 4 of the 5 stations working should a unit suffer a 'fault'.

    This is usually important in a production environment.
     
  3. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    I am no expert, but I agree with Kermit2 that in a production environment, separate power supplies for each work station would be a better choice. In addition to the lesser effect of downtime on multiple stations with a PS per station, rearranging work stations in the event of "new" ideas in work flow would be easier.

    Yes, you would need rectifiers, filter capacitors, and separate 12 and 24 voltage regulators. The design of these linear power supplies is not overly complicated, but requires some experience. In addition, linear power supplies are somewhat inefficient. They waste a fair amount of power in the form of heat, which may be a problem from a "green" standpoint.

    More efficient power supplies are called Switch Mode Power Supplies (SMPS), and they are much smaller and lighter than linear supplies of similar capacity. The design of SMPS is much more complex and it's usually better to buy these off the shelf.

    If I were in your shoes, I would give some serious thought to buying rather than building power supplies for an industrial environment. You won't save much money by building, and they will be "your baby to rock" forever.
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    970
    Just buy off the shelf single (or dual if needed) output power supplies.. 1 x 12V and 1 x 24V for each station should be under $100 for both. A single test stand should ALWAYS have it's own isolated power supply you never want power supply issues/noise influencing other stands.
    Without knowing any other details, here is a simple 24V supply..They have all kinds at this site.
    http://www.mpja.com/24V-65A-150W-Power-Supply/productinfo/16032+PS/
     
  5. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi

    If you are just testing DC motors then you may not need to regulate, or even filter the DC output. You still would need to rectify the output with a 10A rated fullwave, or bridge rectifier.

    Do you need filtering or regulation?

    Regards,
    Ifixit
     
  6. fawcetteng

    Thread Starter New Member

    Dec 11, 2010
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    0
    no, dont need filtering and shouldnt need regulation as long as the voltage is close (for 12 v would be nice to be between 12 and14, for 24 between 23 and 26). does this help?
     
  7. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi

    A 150 to 200 VA transformer with a 24 volt center tapped (CT) output would be good. If you use a 10 Amp bridge rectifier across the full output then you can get either 24 VDC out, or two 12 VDC outputs (wrt CT) from the same transformer. However, only load it with one motor at a time.

    The stall current rating for the motors be tested should not exceed 6 Amps. Fuse the outputs to avoid blowing up diodes if a motor happens to be shorted inside.

    Regards,
    Ifixit
     
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