A DIY & home improvement forum. DIYbanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » DIYbanter forum » Do - it - Yourself » Home Repair
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Home Repair (alt.home.repair) For all homeowners and DIYers with many experienced tradesmen. Solve your toughest home fix-it problems.

A refrigerator on a modified sine wave inverter?



 
 
LinkBack Thread Tools Display Modes
  #1  
Old August 26th 05, 11:31 PM
Toller
external usenet poster
 
Posts: n/a
Default A refrigerator on a modified sine wave inverter?

Harbor Freight has an 800w inverter on sale for $45. It claims to have
surge capacity of 1800w.
My refrigerator draws 13 amps for a second when starting, and then less than
2 amps.
So, will the inverter be able to start my refrigerator?
Is it safe to run a refrigerator on modified sine wave? When they installed
my furnace last year they told me the msw inverters will fry the furnace,
but refrigerators seem less demanding.

I don't plan on using it, but for $45, back up to my generator would be
nice; but not if it will trash a $1,000 refrigerator.

And since I am on the subject, what would happen if I tried to start it with
inadequate current? Would it burn out, or is there a safety feature? I
tried to get an answer from the manufacturer, but they wouldn't tell me.


Ads
  #2  
Old August 27th 05, 12:49 AM
Stormin Mormon
external usenet poster
 
Posts: n/a
Default

I've got a couple inverters which do mod sine. First, a common volt meter
reads 90 volts, not 115. If your meter reads 90, it's just account of the
waveform.

The book I had with mine said that charging things like flash lights or
shavers (which don't use a transformer) will fry the charger. But, the
implication is that charge systems with a transformer are OK.

I don't know the answer about furnace boards. (I'd like to know cause I do
have a mod sine inverter, and also a furnace with a board).

Does your refrig have a circuit board, or is it all analog?

--

Christopher A. Young
Do good work.
It's longer in the short run
but shorter in the long run.
..
..


"Toller" wrote in message
...
Harbor Freight has an 800w inverter on sale for $45. It claims to have
surge capacity of 1800w.
My refrigerator draws 13 amps for a second when starting, and then less than
2 amps.
So, will the inverter be able to start my refrigerator?
Is it safe to run a refrigerator on modified sine wave? When they installed
my furnace last year they told me the msw inverters will fry the furnace,
but refrigerators seem less demanding.

I don't plan on using it, but for $45, back up to my generator would be
nice; but not if it will trash a $1,000 refrigerator.

And since I am on the subject, what would happen if I tried to start it with
inadequate current? Would it burn out, or is there a safety feature? I
tried to get an answer from the manufacturer, but they wouldn't tell me.



  #3  
Old August 27th 05, 01:32 AM
w_tom
external usenet poster
 
Posts: n/a
Default

Modified sine wave means what? Nothing useful because it is
not nor describes a number. One critical number is THD. Does
that inverter even provide a THD number?

Many computer UPSes output modified sine waves. That means
they are 'computer grade'. Another term used to confuse.
'Computer grade' may mean it is only good for computers
because inverter may damage small electric motors. Myths
forget to mention that computers can be more robust than other
appliances. A modified sine wave is not destructive to a
computer but could be destructive to something less robust
such as a furnace.

But again, what is the THD number? It's not which is more
demanding. It's about which is more robust. But then I have
told you little that is useful since I provided a subjective
word (robust) and did not provide numbers.

Toller wrote:
Harbor Freight has an 800w inverter on sale for $45. It claims to
have surge capacity of 1800w. My refrigerator draws 13 amps for a
second when starting, and then less than 2 amps. So, will the
inverter be able to start my refrigerator? Is it safe to run a
refrigerator on modified sine wave? When they installed my
furnace last year they told me the msw inverters will fry the
furnace, but refrigerators seem less demanding.

I don't plan on using it, but for $45, back up to my generator
would be nice; but not if it will trash a $1,000 refrigerator.

And since I am on the subject, what would happen if I tried to
start it with inadequate current? Would it burn out, or is there
a safety feature? I tried to get an answer from the manufacturer,
but they wouldn't tell me.

  #4  
Old August 27th 05, 02:01 AM
Matt
external usenet poster
 
Posts: n/a
Default

Pay attention to whatever Stormin Mormin says, he knows lots and lots
about tricity. Especially pacacitators and circuit breakers.

http://groups.google.com/group/alt.h...403229ce15893c

  #5  
Old August 27th 05, 05:22 AM
Gordon Reeder
external usenet poster
 
Posts: n/a
Default

It would be better to ask this on alt.energy.homepower.
I know that Trace, Xanax and Outback inverters are used
to run refrigerators. I also know that there have been
reports that MSW inverters won't start up furnace motors.

Bottom line: There is a good chance it will work. But,
get better advice on alt.energy.homepower.

"Toller" wrote in
:

Harbor Freight has an 800w inverter on sale for $45. It claims to
have surge capacity of 1800w.
My refrigerator draws 13 amps for a second when starting, and then
less than 2 amps.
So, will the inverter be able to start my refrigerator?
Is it safe to run a refrigerator on modified sine wave? When they
installed my furnace last year they told me the msw inverters will fry
the furnace, but refrigerators seem less demanding.

I don't plan on using it, but for $45, back up to my generator would
be nice; but not if it will trash a $1,000 refrigerator.

And since I am on the subject, what would happen if I tried to start
it with inadequate current? Would it burn out, or is there a safety
feature? I tried to get an answer from the manufacturer, but they
wouldn't tell me.





--
Just my $0.02 worth. Hope it helps
Gordon Reeder
greeder
at: myself.com

Hey EVERYBODY!
Unity means let's try to meet each other halfway
  #6  
Old August 27th 05, 07:32 AM
Jim Yanik
external usenet poster
 
Posts: n/a
Default

w_tom wrote in :

Modified sine wave means what?


It means they use a stepped waveform to simulate a sine wave(instead of a
pure square wave),so it's still full of harmonics,but at lower amplitudes.
So there is less energy at the higher freqs to be dissipated as heat.
But still more than a pure sine wave.

Nothing useful because it is
not nor describes a number. One critical number is THD. Does
that inverter even provide a THD number?


Doubtful.


Many computer UPSes output modified sine waves. That means
they are 'computer grade'. Another term used to confuse.
'Computer grade' may mean it is only good for computers
because inverter may damage small electric motors. Myths
forget to mention that computers can be more robust than other
appliances. A modified sine wave is not destructive to a
computer but could be destructive to something less robust
such as a furnace.


Computer power supplies these days are all switchers,so the input AC is
immeidately rectified and filtered to DC,so the harmonics would not bother
them.They have EMI filters on the inputs anyways,to keep internally
generated harmonics and noise from going out the input lines!

It seems that furnace controls operate on 24VAC from a 60Hz transformer and
the motor runs on 220VAC/60Hz.(I believe).Thats a lot of current for an
inverter to supply,though.


But again, what is the THD number? It's not which is more
demanding. It's about which is more robust. But then I have
told you little that is useful since I provided a subjective
word (robust) and did not provide numbers.

Toller wrote:
Harbor Freight has an 800w inverter on sale for $45. It claims to
have surge capacity of 1800w. My refrigerator draws 13 amps for a
second when starting, and then less than 2 amps. So, will the
inverter be able to start my refrigerator?


No. Don't count on any "surge capacity".

Is it safe to run a
refrigerator on modified sine wave? When they installed my
furnace last year they told me the msw inverters will fry the
furnace, but refrigerators seem less demanding.


Some modern fridges have electronic controls.MSW inverter might harm those.


I don't plan on using it, but for $45, back up to my generator
would be nice; but not if it will trash a $1,000 refrigerator.

And since I am on the subject, what would happen if I tried to
start it with inadequate current? Would it burn out, or is there
a safety feature? I tried to get an answer from the manufacturer,
but they wouldn't tell me.



electric motors do not like undervoltage for any long time period.
"brownouts" burn out motors.
Your inverter output V would drop then either recover,or decide it can't
maintain and shut down all the way.Depends on how sophisticated the
circuitry is;for a inexpensive one,it probably will not have the better
circuitry.

--
Jim Yanik
jyanik
at
kua.net
  #7  
Old August 27th 05, 03:45 PM
Toller
external usenet poster
 
Posts: n/a
Default


"Gordon Reeder" wrote in message
. 3.44...
It would be better to ask this on alt.energy.homepower.
I know that Trace, Xanax and Outback inverters are used
to run refrigerators. I also know that there have been
reports that MSW inverters won't start up furnace motors.

Bottom line: There is a good chance it will work. But,
get better advice on alt.energy.homepower.

Thank you; I will try there.
I presume it is like everything else at HF; cheap as possible, but just
barely doing the job.


  #8  
Old August 27th 05, 05:28 PM
w_tom
external usenet poster
 
Posts: n/a
Default

Without that THD number, then no one can responsibly answer
your question here or there.

Toller wrote:
Thank you; I will try there.
I presume it is like everything else at HF; cheap as possible, but
just barely doing the job.

  #9  
Old August 27th 05, 06:48 PM
Toller
external usenet poster
 
Posts: n/a
Default

I am guessing that THD means total harmonic distortion, so something like
that, and also that HF doesn't provide it.

But, in case they do, what sort of THD would I be looking for?

"w_tom" wrote in message
...
Without that THD number, then no one can responsibly answer
your question here or there.

Toller wrote:
Thank you; I will try there.
I presume it is like everything else at HF; cheap as possible, but
just barely doing the job.



  #10  
Old August 27th 05, 07:02 PM
w_tom
external usenet poster
 
Posts: n/a
Default

2% THD would be sufficient for anything. A higher number on
the inverter should be less than what specs permit for that
appliance (ie furnace). 20% THD is probably what that
inverter is outputting meaning that it causes stress to
refrigerator and furnace - but is more than sufficient for
electronics.

Notice a shortage of numbers. This because too many just
somehow know and don't need the numbers. Well, to answer your
question, numbers are required. There is no way to answer
your question without those numbers. Less than 1% of us
understand those numbers ... which is why the other 99% should
be demanding numbers. So that the 1% cannot blow the whistle,
many manufacturers intentionally don't provide numbers. Then
people in your position only get answers from those who don't
really know such as, "I did it and it did not explode.
Therefore you can also so it."

Toller wrote:
I am guessing that THD means total harmonic distortion, so
something like that, and also that HF doesn't provide it.

But, in case they do, what sort of THD would I be looking for?

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
LCD monitor's Inverter bad ? Rajiv Mehra Electronics Repair 14 January 14th 07 06:30 AM
Inverter shutdown occurs on Dicon/Nextview 17" LCD monitor from 455MHz rf signal. Design flaw? Jay Walling Electronics Repair 4 November 1st 06 12:25 PM
Pioneer Projection TV - Sine wave red convergence line. [email protected] Electronics Repair 0 June 16th 05 01:07 AM
Inverter power needed for Laptop (charger) in car news.rcn.com Electronics Repair 12 June 3rd 05 08:28 PM
Inverter glitch question Nick Hull Electronics Repair 12 October 30th 04 06:52 PM


All times are GMT +1. The time now is 04:38 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.SEO by vBSEO ©2010, Crawlability, Inc.
Copyright 2004-2014 DIYbanter.
The comments are property of their posters.