# Modified Sine Wave Inverters - What is the down side?

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

1. ### Anti-SpamGuest

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 SpenceGuest

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 FinneyGuest

"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. ### Martin RiddleGuest

This typical approximation (5?) is expensive to implement. The 3 voltage
-140,0,+140 is more common.

Cheers

6. ### George GhioGuest

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 GhioGuest

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

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 GhioGuest

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 IIGuest

/delurk

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.

/lurk

10. ### George GhioGuest

And you want to go on record that this is how an inverter works?

11. ### George GhioGuest

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

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...

Semantics;

noun: The study of language meaning

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

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.

Why?

So they can pretend that they bought the more technologically advanced
product.

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.

END.

12. ### George GhioGuest

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

13. ### George GhioGuest

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 GhioGuest

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

15. ### George GhioGuest

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.

- AND IN THE CONTEXT OF INVERTERS "MSW" = "MODIFIED SQUARE WAVE"

16. ### m IIGuest

/delurk

Message-ID: <>
X-Complaints-To:

-----------------------
Here ya go

**** off moron.
----------------------

Message-ID: <>
X-Complaints-To:

----------------------
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!

"name switching"

/lurk

17. ### Steve SpenceGuest

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
http://www.green-trust.org

18. ### philoGuest

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.

http://www.novaelectric.com/inverters_faq.php

19. ### Steve SpenceGuest

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 SpenceGuest

I have no idea how that mistake could ever happen, Tony. You are one of the