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any suggestions for a fast mains changeover system

Discussion in 'Hobby Electronics' started by [email protected], Jan 10, 2004.

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  1. Guest

    I need to make a cct to change over between 2 mains supplies (they are
    in phase). The hard part is it needs to change over within around 5 ms
    which makes changeover relay out of the question. The current switched
    will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
    relay but the nature of the lights is they will drop out for about 5
    mins with an interuption of about 15ms or greater.
     
  2. Mike Harding

    Mike Harding Guest

    Two solid state relays? These are basically opto isolated
    triacs. You'll need a detector/trigger circuit but I don't think
    it would be too involved.

    Mike Harding
     
  3. Ken Taylor

    Ken Taylor Guest

    Is this commercial or are you trying to do a home job on the cheap? There
    are commercial change-over units which will do this, but they are definately
    not cheap, and don't get in the way of the contactor when it changes -
    you'll break your arm!

    Cheers.

    Ken
     
  4. Ken Taylor

    Ken Taylor Guest

    Thought of running them off a UPS so the switch-over doesn't matter?

    Ken
     
  5. amstereo

    amstereo Guest

    If you have 2 powerpoints on different circuits and you tie them together
    nothing bad will happen. However, if Your thinking what i think your
    thinking - ie, tapping off the hotwater supply and automatically changing
    back to regular when hotwater turns off, then you need to use a DPDT
    non-latching relay, that, when it discovers load on the switched line, it
    holds on to that power source and when it goes off, the relay drops and ur
    back on regular. - your refering to MURCURY OR SODIUM LAMPS WHAT ARE YOU
    DOING GROWING WEED?
     
  6. Leon.

    Leon. Guest


    Well he said it was a problem if they drop out for 5 minutes if the change
    over is longer than 15ms.



    I guess he just wants to illuminate his tennis court on off peak power.
     
  7. Rod Speed

    Rod Speed Guest

    UNLIKELY THAT THE PLANTS WOULD
    CARE ABOUT THE SHORT LACK OF LIGHT.
     
  8. bruce varley

    bruce varley Guest

    All the UPS changeover switches I've been involved with have used SCRs, and
    they could switch so that you could scarcely see the glitch on a storage
    CRO.
     
  9. amstereo

    amstereo Guest

    what about a fat capacitor?I couldn't see why a large mains rated cap
    couldn't compensate for a minute loss of power. It'd fill in the blanks (and
    may even help with light flicker during normal operation?
     
  10. Phil Allison

    Phil Allison Guest



    ** What happens if the AC power is lost at or near a zero crossing ???



    ........... Phil
     
  11. amstereo

    amstereo Guest

    Who knows. I'd guess it'd act like caps in pc power supplies, When the power
    drops for split-seconds, most pc power supplies can keep the machine running
    for the extream short duration that they are out, so i guess, itd do the
    same thing.
     
  12. Phil Allison

    Phil Allison Guest


    ** ROTFLMAO - you sure fucking don't !!!!!



    ** What ?? - with no voltage and no stored energy ?????



    ** Still believe in Santa ??

    How about the Tooth Fairy ??



    ........... Phil
     
  13. amstereo

    amstereo Guest

    nah ran out of teeth to loose.

    ever heard of ripple filtering caps? Use a bigger one and it should keep the
    light going for the duration of relay switching.
     
  14. Phil Allison

    Phil Allison Guest



    ** What happens if the AC power is lost at or near a zero crossing ???


    Did I hear someone say deja vu ????




    ........... Phil
     
  15. amstereo

    amstereo Guest

    well What happens if the AC power is lost at or near a zero crossing ???
     
  16. Phil Allison

    Phil Allison Guest


    ** Nothing - your hypothetical cap is simply not charged.




    ........... Phil
     
  17. amstereo

    amstereo Guest

    well
     
  18. Phil Allison

    Phil Allison Guest


    ** **** off imbecile.





    .......... Phil
     
  19. Come on Phil, he is only young.

    amstereo, you cap idea my work for DC. Think about how a cap works.
     
  20. amstereo

    amstereo Guest

    :) not likely
     
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