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Chaining up multiple redundant power supplies

Discussion in 'Electronic Design' started by Ed Kane, Aug 17, 2004.

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  1. Ed Kane

    Ed Kane Guest

    Are there any devices available on the market that will allow me to hook-up
    multiple redundant power supplies to provide higher wattage outputs and
    better power redundancy.



    Something like chaining up four of the following 3x225W (N+1 450W) redundant
    power supply together to provide >1800W of total power.



    http://www.rackmount.com/Rackacc/RP8450.htm



    Has anyone done this before?
     
  2. There would be nothing available "off the shelf" to adapt normal power
    supplies, as the load sharing is integral to the power supply design itself.
    Or, if it isn't already, it needs to be.
    While you might be able do that, keep in mind its true value comes from the
    redundancy. So you're limited to total shared power minus one unit. Obviously
    more beneficial with more than two units in that case.
    Further chaining existing redundant supplies might be easier, but you have to
    work out how they've done it, and adapt that. Not only that, in your above
    case, it would be better to start off with higher power units, as using
    multiple (well, more than three) power supplies over your entire load ends up
    being expensive.

    The situation gets more complicated if the power supply has post regulated
    outputs. You have to share those loads separate from each other. There is
    also the requirement of all post regulated outputs being able to be controlled
    in a similar manner, and this is not always the case depending on design.
    I've had been seriously looking at doing it "on the cheap", but once you
    factor in the extra tray connectors, time and money spent, it ends up much
    easier and cheaper to just buy it outright.

    Though, the cool frankenstein factor would be great value amongst our geek
    friends...
     
  3. The outputs can be adjusted if the power supplies have been designed
    with load sense wires. Many power supplies and power supply modules
    have this feature.

    There are lots of load share controller chips available, from ST, TI,
    Linear Tech. etc.
    These will use the power supply sense lines to adjust the output
    voltage of each supply so that the load current is shared.

    Regards,
    Allan.
     
  4. You're right. I've looked it up soon after sending that message. All you
    need is a current sense resistor on each output, a shared line, and control of
    the regulator feedback.

    Though, I don't see any DIY "neat" solutions, unless you're adapting some
    other type of cabinet or enclosure..

    I've just checked up on prices here in australia, and they don't look
    favourable. They stand at about three times the price of two "normal" power
    supplies on their own.

    Looks like I'm going to have to 'jim robinson' something up myself after all.
     
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