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Constant Voltage Transformer Question

Discussion in 'Electronic Design' started by Jim Thompson, Dec 31, 2004.

  1. Jim Thompson

    Jim Thompson Guest

    A major pain-in-the-ass in Arizona is lightbulb lifetime, particularly
    this time of year, where one day will require heat and the next not.

    So the AC voltage regulation sucks... often popping up to 130VRMS.

    I was wondering how Constant Voltage Transformers would perform with
    lamp loads.

    I'm thinking of room-by-room regulation for ceiling fixtures... since,
    15' up, it's tricky with a lamp changer pole :-(

    I have easy attic access, pull-down-stair ladders, and the attic is
    tall enough that I can stand upright to work in most locations.

    ...Jim Thompson
     
  2. John Stewart

    John Stewart Guest

    The Solas used to make lots of odd order harmonics.
    But incandescent bulbs don't care.
    Induction motors don't like that at all.

    Cheers, John Stewart
     
  3. Why don't you get away from incandescents and go with CFLs? After I
    posted that thread "CFLs for a buck seventy-nine", Home Depot had a six
    pack of corkscrew CFLs for even less than that. At those prices, if
    they last twice as long as incandescents, they'll more than pay for
    themselves in electricity savings. Amd you only have to change them
    half as often, if that much.

    I'm sure you'll get other expert opinions, especially from Don K. I've
    been happy with the cheap CFLs I've been using, So..

    Or you can probably pick up a Triplett or whatever ferroresonant
    transformer in a box for cheap, and if you can stand the buzzing, it
    should help.
     
  4. I read in sci.electronics.design that Jim Thompson
    4ax.com>) about 'Constant Voltage Transformer Question', on Fri, 31 Dec
    2004:
    There might be 'start-up' issues, if you have a fitting with a lot of
    lamps in it, due to inrush current, but AFAIK CVTs work very well with
    resistive loads.
    Why not regulate all the lighting circuits with one CVT?

    You do know that they are liable to hum, don't you? And, no, they can't
    learn the words.
     
  5. Voltage stabilizers are pretty common in third-world countries. I
    can't remember where I've seen them for sale though. They look like
    the usual metal box with a transformer in it (like 120/240
    autotransformers). Not very expensive (China/India etc.). Mohammed has
    one here, but he's got little feedback and the item location seems a
    bit odd (is it NYC or is it Houston, "Taxes"?).

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4660&item=3862579284


    Best regards,
    Spehro Pefhany
     
  6. Jim Thompson wrote...
    Why not change to electronic mini-fluorescent lamps? I'd imagine
    they aren't very voltage sensitive and now they're available with
    decent color-temperature phosphors, and some can work with dimmers.
    Save on electricity, cooling energy, and manpower.
     
  7. Jim Thompson

    Jim Thompson Guest

    Probably too much for one transformer... I have 500W just in the
    kitchen; but I'm open to suggestions... all the ceiling lighting is
    off of a single sub-panel.
    Sno-o-o-o-o-rt ;-)

    ...Jim Thompson
     
  8. Jim Thompson

    Jim Thompson Guest

    Do they make those with floodlight shaping?

    I haven't been impressed with the light output of the CFLs I've seen.

    I have 5x 75W halogen floods just over the cooking area... 15' up,
    that's barely adequate.

    ...Jim Thompson
     
  9. I read in sci.electronics.design that Winfield Hill <[email protected]_rowland-
    I didn't recommend them for that specific reason. The problem is the
    rectifier filter cap. It is quite heavily stressed with voltage and
    temperature when the lamp is running at its rated voltage, and I didn't
    like to guess the life at 130 V input.
     
  10. Yes, but the ones we've tried have woefully inadequate light output. I
    use the 85W incandescents in some places, because the 65W ones are too
    dim for my eyes. The floods and the small base ones (candelabra based
    etc.) are two weak spots right now. The regular replacement bulbs are
    pretty good and we've got them in most places that used to have
    indandescents. I'm going to try conformally coating one and put it in
    the MB shower fixture unless Home Despot carries small outdoor types.

    Best regards,
    Spehro Pefhany
     
  11. I read in sci.electronics.design that Jim Thompson
    4ax.com>) about 'Constant Voltage Transformer Question', on Fri, 31 Dec
    2004:
    You won't get a household-type CFL with as much light output as a 75 W
    halogen. Do the luminaires have to be 15 feet up? Three 35 W (or so; I
    don't know what ratings are available for 120 V) linear fluorescent
    tubes would give you more light, but you would need to arrange a
    suitable luminaire.
     
  12. Jim Thompson

    Jim Thompson Guest

    That's where the ceiling is ;-) (They're recessed PAR3 floods.)

    ...Jim Thompson
     
  13. Dan Mills

    Dan Mills Guest

    Silly thought, but if the load is just incandecents, why not just use a big
    thyristor dimmer to (possibly automatically) trim the RMS value to whatever
    you happen to like?

    seems like it would be smaller and lighter then a CVT and would probably hum
    less.

    Regards, Dan.
     
  14. artie

    artie Guest

    Been a while since I dealt with these beasties, and I'm operating under
    the influence of OTC cold medication, but I seem to remember the
    constant-voltage devices were saturated-core, and ran hot and noisy.
    Had a 6800 development system (Jupiter II, all wire-wrapped) which used
    a ferroresonant transformer. Hot and noisy! And if I leaned back in
    my chair while using the phone, the headset got close to the thing,
    inducing all sorts of fun into the conversation!
     
  15. Jim,

    Why not look into Buck and Boost setups. Sounds like 500W's is doable with a small buck transformer in series during the peak.
    Usually its employed for Brownouts in the boost configuration. A relay and some hysterisis switching will keep the bulbs in a happy
    range of voltages.

    Happy New Year!
     
  16. JeffM

    JeffM Guest

  17. James Meyer

    James Meyer Guest

    Ferroresonant transformers have terrible efficiencies. If you want to
    double your power usage, they're great! Although Jim T's description of his
    house seems to indicate that power usage is the least of his worries. :cool:

    Jim
     
  18. Jim Thompson

    Jim Thompson Guest

  19. I've seen big variacs with servo-controlled motors that keep
    the line voltage constant.
     
  20. The Phantom

    The Phantom Guest

    Here in the Pacific Northwest, high line voltage is the norm (130V is quite common).
    Home Depot and others sell incandescents rated at 130V. Since the life of incandescents
    varies as the inverse of the 12th power of the applied voltage, switching from 120V bulbs
    to 130V bulbs makes quite a difference.
     
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