Power supply

Discussion in 'General Electronics Chat' started by Awesome Girl, Apr 11, 2013.

  1. Awesome Girl

    Thread Starter New Member

    Apr 11, 2013
    hi! I'm working on a project that involves different apparatus. one of which is unregulated variable voltage DC power supply.

    The instruction says:

    "A shop built dual unregulated variable voltage DC power supply.
    This supply was built from two 0 to 90 VDC power supplies that
    were designed to supply power for permanent magnet DC
    motors with a 90 volt armature circuit. This makes available a
    variable DC voltage of 0 – 90 volts at 10 amps. Power supplies
    for releasing brakes up to 90 VDC. Second supply is for lockingup the rotor for alignment checks."

    I need to build the supply but I'm still confused about how it has to be done. I was thinking of getting two 0-90V unregulated variable voltage DC power supplies and connecting them in series. This doesn't seem right to me though!

    Is there any other way that I can build this supply?

    Thank you
  2. Eric007

    Senior Member

    Aug 5, 2011
    Welcome to the forum!

    Hope you get some fun here...:)

    And gudluck with your project!
    Awesome Girl likes this.
  3. Brownout

    Well-Known Member

    Jan 10, 2012
    How much have you worked around voltage this high? I hate being the nanny goat, but this voltage can kill, and I'd be irresponsible to encourage someone do proceed if they aren't experienced in working with lethal voltages.
    Awesome Girl, absf and Metalmann like this.
  4. #12


    Nov 30, 2010
    Putting (2) 90 volt supplies in series would make 180 volts, and that is not at all what you need. That is easily enough to kill you. The fact that you asked in this way makes us worry.
  5. Mike33

    AAC Fanatic!

    Feb 4, 2005
    AWFUL lot of current going to that motor...like they said...there's definitely the potential for a bad, bad safety problem here!!!
    Awesome Girl likes this.
  6. Mitch conrad

    New Member

    Apr 10, 2013
    It sounds like you working on some industrial application, there should be a manufacturer that could supply you with the right parts if that's the case. If so it would be best to try other alternatives before trying to build a high voltage power supply.

    You could even cannibalize power supplies from equipment with similar specs if you want to go cheap.

    I don't know how experienced you are ,but if you are inexperienced with high voltages building a power supply like this could be a bad idea.
    Awesome Girl likes this.
  7. Awesome Girl

    Thread Starter New Member

    Apr 11, 2013
    Hi! thanks for your replies. I don't have experience at all. I am working on my first project in an industry and it requires equipment that we don't have. when going through the list of equipment we need I saw that instruction about the power supply.
    I thought we needed to build it but I don't wanna die now.
    I'll try to find out manufacturers who can supply it.

    Reading the instruction again makes me think that we might not even need a dual power supply. We can just have 2 supplies, 1connected to release the brake and the other connected to the rotor. Am I right?

    All I need for now is to tell my superior what we need and how we can make or get it.

    Thanks for your help
  8. BillB3857

    Senior Member

    Feb 28, 2009
    It sounds like you are trying to align Brushless DC motors to their encoders. You will need two supplies. You will need a power supply to release any brake that the motor may have. Some are 90VDC and some are 24VDC, so a variable DC supply is in order. As for supplying power to provide lockup for alignment, it really doesn't take that much DC volage to be able to lock the rotor into a position but current may be higher than you would expect. After all, the only resistance is what is in the windings. A variable voltage is appropriate since you don't want to put more power into the windings than is needed to accomplish lock-up.
    The links below will show you two examples of what should work for you.


    http://www.mpja.com/0-30V-0-3A-Variable-Benchtop-Power-Supply/productinfo/9616 PS/
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