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Modified Sine Wave Inverters - What is the down side?

Discussion in 'Photovoltaics' started by Anti-Spam, Mar 28, 2007.

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  1. Anti-Spam

    Anti-Spam Guest

    Cant seem to find a FAQ for this group, so am posting this question.
    What is the down side to "Modified Sine Wave" inverters?

    I assume modified sine wave = square wave after being passed through
    an inductive circuit.
  2. Guest

    The first wise remark would probably be that there is no need to modify a
    sine wave, you should refer to modified square wave.
    I don't subscribe to that. I prefer to accept industry buzzwords.
    I think the method of making an acceptable pseudo sine wave varies by
    manufacturer. I think my Fronius produces a 400Hz stepped pattern modeled
    to follow the incoming AC sine wave.
  3. Steve Spence

    Steve Spence Guest

    1. Switching power supplies are pretty much immune to msw waveforms. Most
    small computer ups's are msw, and most computer equipment doesn't care.
    laser printer are an exception.

    2. I have not seen this behavior either. MSW are typically a few points more
    efficient than a sw unit. The battery doesn't care.

    3. usually correct.
  4. Ken Finney

    Ken Finney Guest

    "Modified Sine Wave" isn't a "rounded" square wave like an inductive circuit
    would provide, it is more like this (hope the ASCII art comes through):
    __| |__
    | |
    ----| | |--------
    | |
    |__ __|

    The energy under the curve approximates the area under the curve of an
    equivalent sine wave.
  5. This typical approximation (5?) is expensive to implement. The 3 voltage
    -140,0,+140 is more common.

  6. George Ghio

    George Ghio Guest

    MSW = Modified Square Wave

    Because it is a square wave. Why would you modify a sine wave?

    Any other definition is sales hype to confuse newbys into thinking they
    are buying a better machine than they really are.
  7. George Ghio

    George Ghio Guest

    Anyone who spruks MSW as being "Modified Sine Wave" is either lying or

    The first inverters were simple square wave. The next generation were
    modified to approximate a sine wave, hence "Modified Square Wave" (MSW)

    No body has, to my knowledge, ever modified a sine wave to approximate a
    square wave in a home power inverter. This is probably because sine wave
    is the ideal.

    It would seem that I can read. A Modified Square Wave may well look more
    like a sine wave on a scope, but it was never Modified from a Sine Wave.
    It's origin was a Square Wave that was Modified. Therefore it has been,
    is now, and will always be, a "Modified Square Wave".

  8. George Ghio

    George Ghio Guest

    As I said, Anyone who spruks MSW as being "Modified Sine Wave"...

    If you modify a "Square Wave" you get a "Modified Square Wave".

    If you modify a "Sine Wave" you get a "Modified Sine Wave".

    Ya all have a nice day now.

  9. m II

    m II Guest


    As much as you try to educate George you will reap more of the
    same from that klutz.
    What is amusing to see is George and the Trannie, Gymmy Bob
    aka SolarFart aka Janet aka Janice aka Mabs aka Pizza Girl, get
    juxtaposed on terminology - a poignant example of the Blind leading
    the Blind, or Dum and Dummer going at it to impress, themselves!

    None of which of course helps anyone. That goal they also share.

  10. George Ghio

    George Ghio Guest

    And you want to go on record that this is how an inverter works?
  11. George Ghio

    George Ghio Guest

    While I was willing to let it lie, it seems you want to continue the

    You accuse me of playing with "Semantics". Of course I'm playing with
    semantics. After all we are discussing the meaning of words. It begs the
    question of whether you know the meaning of the word "Semantics". So to
    set the rules, as it were...


    noun: The study of language meaning

    adj: Of or relating to the study of meaning and changes of meaning;
    "semantic analysis"

    Please note the adjective.

    MSW in the context of inverters and home power systems means "Modified
    Square Wave".

    You are incorrect to bring your linguistic baggage from a different
    industry. It may well be that the definition you are so fond of is
    correct in electronics, but the context is inverters.

    I suspect that you also suffer from the need to use a name that sounds
    more impressive. This is a common trait among tinkerers. People who do
    not have the expertise love to use jargon to appear more knowledgeable
    on a subject than they are.

    Modified Square Wave is just not as impressive as as Modified Sine Wave.

    If you were to take two identical inverters, paint one white and the
    other black, label one as a modified square wave and the other modified
    sine wave, price the modified sine wave at $10 more, posers like you
    will always buy the one labeled modified sine wave.


    So they can pretend that they bought the more technologically advanced

    When they are asked about their system they say, "Oh yes, my inverter is
    a mumble mumble sine wave inverter".

    Semantics? Hell yes.

    If the inverter you bought was a called a "Modified Sine Wave" inverter
    then the seller was lying and trying to make you believe that the
    product he was selling you was better than it really is.

    In twenty years of using, living with, designing and installing solar
    power, I have seen all the lies, half truths and cons there are.

    You can call your inverter what you want, but if it is as a MSW inverter
    you are only fooling yourself if you think it is a sine wave inverter.


  12. George Ghio

    George Ghio Guest

    See post 2/4/07 9:24 PM.

  13. George Ghio

    George Ghio Guest

    In the absence of intelligent response I will assume that you have
    accepted my position on the subject as correct and that you retreat to
    the time worn comfort of total ignorance.

    Ya all have a nice day now.

    P.S. The term was coined the day the first Modified Square Wave inverter
    was made. Given your level of childish denial, this was probably before
    you were born.

  14. George Ghio

    George Ghio Guest

    As I am sitting here looking at the time stamp on the post in question,
    I must assume that your intelligence is that as indicated when you
    answered a question with your sad tirade.
  15. George Ghio

    George Ghio Guest

    Why thank you for that insight to your mental abilities. Right up there
    with Runaway.

    TLA's are industry specific. The fact that you know one of them does not
    mean you know them all.

    If you want to answer this post try to do so with an intelligent
    response. So far you position has relied only on the "Because" argument,
    perhaps you would like to add the "Why" argument.

    "MSW" is an acronym that may stand for any of the following:

    - in academia and as a title, "Master of Social Work"

    - Mammal Species of the World, a publication of recognised mammal species.

    - "Municipal solid waste"

    - a sub-discipline of social work, ''medical social work''

    - in computing:

    - "Microsoft Windows:"M"icro "s"oft "W"indows"

    - Machine Status Word on 286 processors (on 386 processors it is simply
    the low 16-bit of CR0 for backward compatibility)

    - in particle physics, the Mikheyev-Smirnov-Wolfenstein effect

    - in recovery, "Marin Services for Women"

    - the Massawa International Airport in Massawa, Eritrea.


  16. m II

    m II Guest


    Message-ID: <>

    Here ya go

    **** off moron.

    Message-ID: <>

    George, You have been duped by the supertroll imposing as myself

    First class mule George may be but retarded he is not.
    Now you know something about NNTP try and use
    one of those "free servers" to really spin George out!

    Complaint filed with
    "name switching"

  17. Steve Spence

    Steve Spence Guest

    You left me off the list. You seem to have everyone else on there that has
    ever disagreed with you. Paranoia will destroy ya. I happen to know wmbjk,
    William P.N. Smith, and Lectron_Nuis, and they have never impersonated
    anyone ever. The others I can't speak for.

    Steve Spence
    Director, Green-Trust
  18. philo

    philo Guest

    If you take an square wave and run it through a ferroresonant transformer...
    you have an essentially perfect sine wave.

    The so-called modified sine wave inverters are basically a double-step
    square wave inverter....
    For most applications that's good enough.

    More reading here
  19. Steve Spence

    Steve Spence Guest

    Who has? I mentioned three different folks. Sorry, but I don't believe you.
    My contact info has been and is always on my website. Knock yourself out.
  20. Steve Spence

    Steve Spence Guest

    I have no idea how that mistake could ever happen, Tony. You are one of the
    clearer heads on this medium.
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