Convert ATX PSU to run on 192V DC rail

Discussion in 'Computer Information' started by WiseIndian, Jun 10, 2004.

  1. WiseIndian

    VWWall Guest

    This, obviously, should say: Your *192 V DC* is far too low. Put
    another way, 192 V DC at the input to the switching circuits would
    correspond to an input of 72/136 V AC, below the low limit design of
    90/180 V AC. The PSU would not even attempt to start at this level.

    Virg Wall
    VWWall, Jun 11, 2004
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  2. WiseIndian

    kony Guest

    IIRC, most if not all of the Active PFC units don't have a voltage
    doubler, if we can take it for grated that having only one HV cap on the
    HV side is evidence of a non-doubled design.

    However, I"m not so sure of the viability of setting up this multi-dozen
    system arcade as OP wants... It would require replacing all the power
    supplies with, at a minimum, signficantly higher than average priced
    units, then a customized power grid to deliver the 192V DC... it is not
    going to meet code to use the existing AC wiring and outlets to deliver
    192V DC, so less common, more expensive couplers will be needed at
    multiple points.

    Once one starts adding up the costs then the difference in energy
    consumption, energy cost, may not be recouped within projected lifespan of
    these gaming systems. If power generation is the issue then perhaps a
    different UPS, modification to existing UPS, or alternate energy source
    would be beneficial.
    kony, Jun 11, 2004
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  3. WiseIndian

    VWWall Guest

    This, of course should read: "Is it then applied to an invertor and..."
    Typo: (240 x 1.414 = ~340 V DC)
    Webster's Dictionary: rectify 1) To make or set right ;-)
    4) To make an alternating current unidirectional.

    Sorry, it was getting late! :-(

    Virg Wall
    VWWall, Jun 11, 2004
  4. WiseIndian

    VWWall Guest

    I'm curious. I always thought they used something like "steering"
    diodes to select the voltage range. I can't imagine a switching circuit
    that would work over a range of 127-340 V DC (90-240 V AC input). That
    would imply a current range of 2.67/1! What is the voltage at the HV
    side? And how does it get there? Anybody know?

    Schematics for any ATX supplies are scarce. Anybody have any sources?

    Virg Wall, K6EVE
    VWWall, Jun 11, 2004
  5. WiseIndian

    kony Guest

    I have one, around here "somewhere", LOL...
    Have been pretty busy these days but if I get a chance and can find it,
    I'll take a look at it. Well, I can "look" at it now since I have a
    picture handy but that's not quite enough.
    kony, Jun 11, 2004
  6. WiseIndian

    Ryan Guest

    What you want is a "full input range" ATX supply. Do not get an
    "auto-switch" supply as these have voltage doublers that won't work
    with DC.

    I am willing to bet a full input range supply will work just fine on
    DC without modification, and most spec 90-264 VAC which is 127-373
    VDC; indeed within your 192 VDC rail.

    Ryan, Jun 11, 2004
  7. WiseIndian

    N. Thornton Guest

    You still dont seem to addressing the simple question of whether a PC
    PSU is likely to work on 192dc. Thats the q here, marketing has
    nothing to do with that. Design optimisation is not marketing.

    Regards, NT
    N. Thornton, Jun 11, 2004
  8. WiseIndian

    Tam/WB2TT Guest

    Well, if you have a supply built for 95 -135 VAC operation that does not
    use a voltage doubler it should work. 135 x SQRT(2) =190, close enough. Now
    the question is does the supply need AC for other reasons. When the PC goes
    into standby the fan stops; I don't know for a fact, but suspect the main
    supply also might shut down. Where does the keep alive voltage come from?

    Tam/WB2TT, Jun 12, 2004
  9. WiseIndian

    ric Guest

    Depends on the supply design. Some use a small bias transformer off of
    the AC input, and some use a switching design off of the 300v buss.
    Whether his 192VDC would support the latter is a good question. If his
    supply used the former, he'd be SOL.

    I'd use an AT rather than a ATX supply, if possible.
    ric, Jun 12, 2004
  10. WiseIndian

    Robert Baer Guest

    Incorrect; any switcher will work from DC - by definition!
    What do you think happens to the incoming AC?
    It gets rectified, and due to a fairly large capacitor, gets turned
    Robert Baer, Jun 12, 2004
  11. WiseIndian

    Tam/WB2TT Guest

    Thanks, that's what I was guessing. More things to consider are the fact
    that the 192V would actually be about 225 the instant the charger stops, and
    around 170 when the battery is about to poop out. Also, there are two basic
    kinds of UPS. The full time runs the output off the inverter all the time,
    on the other kind the load is run off the AC line, and then switches to the
    inverter when the AC goes bad. In the second, the inverter efficiency is
    irrelevant except when running off the battery. In an elaborate system like
    this, though, it may be full time.

    There are people who run hundreds of servers in one location. It would be
    interesting to find out what they do. Surely they must have backup power.
    Common backup voltages in other applications are 48, 135, and 270V. Not sure
    they make an AT supply with the right output voltages.

    Tam/WB2TT, Jun 12, 2004
  12. WiseIndian

    Ian Stirling Guest

    I've seen some (few) that require AC to startup.
    Ian Stirling, Jun 12, 2004
  13. WiseIndian

    Nico Coesel Guest

    Why not dump the on-line UPS and buy an offline UPS? Problem solved.
    An on-line UPS is more prone to problems anyway because its inverter
    is always on.
    Nico Coesel, Jun 12, 2004
  14. WiseIndian

    WiseIndian Guest

    saving potential is huge.
    The maximum offline UPS capacity I can lay hands on is 3KVA and can
    support maximum of 6 Machines and since we use 17" CRT( LCD cannot
    refresh fast enough for gaming) the unit's we tested worked @ just 50%
    reliability during outages.

    actually i am more intrested in the loss at the online UPS end, from
    what I measured the UPS Input= [email protected] and output = [email protected]
    thats a loss of 25% our 6KVA ups is drawing like 80KWh daily.
    WiseIndian, Jun 13, 2004
  15. WiseIndian

    DevilsPGD Guest

    In message <>
    Do you need 6 machines on one UPS? In general, individual UPSes will be
    more economical until you're looking at a minimum of 20 PCs or so, only
    then is it worth investing in a commercial unit to run an entire office.

    Ballpark pricing was done about two years ago, but I doubt much has
    changed other then everything has dropped somewhat.
    DevilsPGD, Jun 13, 2004
  16. WiseIndian

    Rich Grise Guest

    Your safest bet is to take one of the existing power supplies, open
    it up, and measure the raw DC. If it's like half, or 2X, try the
    comp. PS on a different line voltage.

    It might have enough input compliance to manage 192V, but if you
    get something wacky like 250 VDC, I'd be a little iffy about connecting
    it directly. (i.e., if they somehow get 250VDC for the rectified line,
    I wouldn't put 192V into it.)

    And if it is in an iffy range, go ahead and get a proper fuse, and
    hook one up and see if it smokes!

    Have Fun!
    Rich Grise, Jun 15, 2004
  17. WiseIndian

    Rich Grise Guest

    If the 192 supply is a stack of ordinary lead-acid batteries, there
    must be 48V taps. And depending how many you need, 192V input might
    not be that much more money.

    Good Luck!
    Rich Grise, Jun 15, 2004
  18. WiseIndian

    CBFalconer Guest

    If it is lead-acid cells, a normal cell voltage is 2.2, which
    means that the 192 V nominal will probably be 211 V. I would not
    be surprised to see 224. All assuming 96 cells.
    CBFalconer, Jun 15, 2004
  19. The question is whether the OP already has a 192V DC rail that he has to
    put to use, or if its early enough in the design stage to change the
    spec to an industry standard. Telecom gear uses 48V extensively, so
    chargers, supplies and other goodies are readily available.
    Paul Hovnanian P.E., Jun 16, 2004
  20. WiseIndian

    Ken Taylor Guest

    92VDC UPS rails are indeed a standard value. There are companies which do DC
    input PC power supplies (two at hand are VOXTechnologies and BPS), they may
    be able to help with a 192VDC in supply. Alternatively, a 192V to 48V
    converter plus one of the 48VDC in supplies. best advice would be to ask the
    UPS manufacturer which of these they could provide or recommend.

    I don't want to be a PITA, but I assume that is a *big* 3-phase UPS - you DO
    realise it can kill you??

    Ken Taylor, Jun 16, 2004
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