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Stacking or Paralleling Inverters????

Discussion in 'Electronic Basics' started by J Poy, Jul 29, 2004.

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  1. J Poy

    J Poy Guest

    I have 2 small Xpower Plus 400W inverters (Xantrex) and I would like to
    connect them in parallel to increase the overall power output. 4+4= 800W.

    I call Xantrex the manufacturer and the customer service technical support
    said it could not be done. They refused to connect me to the engineering
    dept. when I ask for a schematic diagram.

    Has anyone been successful in stacking two of these inverters or knows where
    I can get schematic drawing.

    Things I have thought of:

    .... Output voltage must be in phase both units. How you ask by using the
    same sync pulses to drive both inverters. Next question would be is the sync
    pulse for one unit be capable of driving to inverters?

    .... Could output load balancing be problem? I am not sure?

    I am sure there could be more problems.

    Any suggestions where I can get some information on this subject? Please and
    Thank You.

    Jim
     
  2. Rich Grise

    Rich Grise Guest

    I've seen inverters in parallel, and yes, they simply used the same
    sync line. But they were designed to work that way. I'd be very careful
    if I were going to hack a couple of commercial units.

    Of course, it will void the warranty. They didn't want to talk to you
    because of the liability problems if they let you even _think_ they'd
    approve such an arrangement.

    Open the units, take a look, and if you have the electronics background
    to do it safely, then do it, otherwise, leave them intact, sell them,
    and buy a bigger unit. If they have "Warranty Void if This Sticker is
    Removed" stickers, then be aware that they're extremely difficult to
    remove without it showing.

    Good Luck!
    Rich
     
  3. repatch

    repatch Guest

    Don't even bother THINKING about doing something like this. Buy a bigger
    inverter.

    On Thu, 29 Jul
     
  4. Dan Fraser

    Dan Fraser Guest

    I agree. If you don't know why this is impractical except for a very
    experienced engineer, you can't do it. However, the services of an
    experienced engineer, like myself will cost more than a bigger inverter.
     
  5. jriegle

    jriegle Guest

    If you don't care about hosing the inverters, why not try?
    If you could tap the clock output on one, disable the clock on the other and
    bring the signal over, It could possibly work.
    As you say, phasing could be an issue. The clock signal may be high since
    many things go on inside the inverter in a nornal 60 Hz cycle. Some units
    adjust the output pulse width for regulation. getting all this in sync could
    be a problem.
    John
     
  6. Checkmate

    Checkmate Guest

    On Thu, 29 Jul 2004 14:51:49 -0400, J Poy put forth the notion that...

    The solution is simple... sell the two 400 watt units, and buy an 800
    watt unit. You're not going to be able to get two of them to stay in
    sync.
     
  7. bushbadee

    bushbadee Guest

    We did it all the time at Electro Solids corp.
    But our inverters had inputs for syncing them together.
    If you want to do that, get inverters with syncing ability.
    But unless the converters are short circuit protected with the voltage
    falling off into a short rather than just turning off do not parrelel
    converts.

    What will happen when you parrellel converters is the one with the hightest
    output voltage will carry as much of the load as it can and then go into
    overload so the voltage will fall till it matches the output voltage of the
    one in over load and then it will take up the remainder of the load.

    If the two converters are synced, it is better to put the outputs in series
    with each supplying 1/2 the load. voltage.
    You can put both in series and use a step down tranformer to accomplish the
    same thing.

    But in general, I would say, if you have to ask, you should not do it as you
    just do not understand what is involved.
     
  8. bushbadee

    bushbadee Guest

    We did it all the time at ElectoSolids Corp.
     
  9. But, as you said in your earlier post, your units were made to do that.
    This is just not a do-it-yourself, hobbyist undertaking. Without the
    proper experience (doesn't have it), full schematics (doesn't have
    them), lots of test equipment (meters, scopes, etc. - if he has all
    that, he should be able to afford an 800kva inverter, they're a lot less
    expensive than a trip to the emergency room), and more than a little
    careless disregard for safety (both his and whoever winds up using this
    contraption), this is better left alone.

    Al
     
  10. bushbadee

    bushbadee Guest

    I agree with you completely.
    And I basically so stated.
    I just told him that it could be done and that it has been done.

    But I also said and have often said this, if you have to ask how to do it,
    then you shouldn't try to do it.

    When fooling around with 400 and 800 va inverters which can give you a quick
    trip to the cemetary, that holds double true.
     
  11. Jimmie

    Jimmie Guest

    May be interesting to try. Take two inverters, I believe the ones in
    question of the self excited type where all you have is a transformer and a
    couple of transistors. Monitor them and when they get in phase through a
    switch connecting them together and see if they lock or melt down. Probably
    would be safe enough to try if they were connected together with a 2 amp
    fuse for initial test.
     
  12. oops, I meant 800va, not 800kva.

    Alan Stiver, PE wrote:
    .... he should be able to afford an 800kva inverter, they're a lot less
     
  13. J Poy

    J Poy Guest

    Hi everyone!

    Thought I'd let you know what I decided to do:

    .... Without a schematic well it's like going on a trip without a map, if you
    know what I mean. You can get there but might take you along time. I hoping
    someone might have a schematic of this inverter.
    .... Your all right with regards to the dangers of trying to actually
    parallel two of these inverters, but I really wanted to hear someone who
    might have actually done this with these particular ones.
    .... My background is in electronics, but as I see it why try to invent the
    wheel if someone has already done it. I am not working on inverters per say,
    but I do have a electronics degree and have study inverters in the past.
    .... Yes I do have all the electronic (Scope, DVM, generators etc.) equipment
    to perform the work safely to the inverters as well to me.

    In the end I have decided to hold off for now and try to more research on
    the subject.

    Thank you all for your comments!

    Jim
     
  14. bushbadee

    bushbadee Guest

    Real inverters is a very specialized subject that they do not teach in
    Colleges.
    The secrets were passed passed on to me by a German scientist.
     
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