Poll

has a squarewave inverter damaged or shortened the life of your appliances?

No, not at all
8 (34.8%)
Yes, but not by much
4 (17.4%)
Yes, by around one third of the average life expectancy
1 (4.3%)
Yes, by half of the life expectancy
1 (4.3%)
Yes, by two thirds of the life expectancy
0 (0%)
Damn....mine caused an appliance to overheat and it burn down my house!
2 (8.7%)
I don't have an Inverter
7 (30.4%)

Total Members Voted: 21

Author Topic: has a squarewave inverter damaged or shortened the life of your appliances?  (Read 15416 times)

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admin

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(poll)
« Last Edit: February 18, 2010, 09:19:27 PM by scoop »

dbcollen

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How could you tell?

TomW

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How could you tell?

Darned good question.

I have worked with appliances and electronics for decades and pinpointing the failure root cause is non trivial even for a pro.  Oh sure, you can say "R5 failed". Why is a bit tougher.

Should be a question like "do you think / believe ..."

Tom

bob g

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fwiw, and ymmv, and all that said first

most all motors, and things that use transformers and relay coils like pure sine wave,
if you power them with modified sine, they will run hotter than they would otherwise on pure sine
and if you feed them with square wave, they will run much hotter

having said that, most appliances seem to tolerate the added heat from what i can tell, but
i would expect any appliance that is marginally engineered to suffer some longevity if not provided with pure sine wave power.

having read on here and various other forums relating to offgrid life, folks get very anal about a few milliamps here and there
but pay no mind to the inverter that they use, mainly because the advertised efficiency of a modified sine/square wave inverter
is usually quite high and in some cases equal too or surpassing the pure sine wave inverter, but

folks don't consider what the added heat represents in the motor or transformer loads, that heat relates to added losses
it takes power to make heat.

the thing is, a pure sine wave inverter is likely more efficient overall powering a specific motor load even if it is listed at 90% vs
a modified sine wave that might be listed at 92-93%, the added efficiency is eaten up as heating in the motor load, leaving the overall
efficiency likely much lower than the pure sine inverter listed efficiency.

to me the better discussion might include an analysis of this phenomenon, where folks get all knotted up chasing down a few tenths of an amp
and then burn several extra amps making heat with a modified sine inverter driving a motor load like a refrigerator?

i suspect that there is much more to be said for buying the pure sine wave if possible to start with, the appliances "might" last longer, and the system overall efficiency will likely be higher as well.

over time, maybe not a very long time either, the added cost might quickly pay off?

btw, the only things i have heard of damaged by modified sine and especially square wave inverters are smart chargers for portable tools and
some cellphone chargers. i have seen a few of each burnt up using modified sine inverters.

bob g
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large frame automotive alternators for high output/high efficiency project X alternator for 24, 48 and higher voltages, and related cogen components.
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jacobs

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I had a square wave inverter burned out by an appliance. In the last 31 years I've had 4 different high quality modified sine wave inverters and haven't had any problems with any appliances. For me, pure sine wave is not needed nor wanted.

WindriderNM

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #5 on: September 26, 2010, 06:38:06 PM »
I wasn't able to place my vote.
I have lost 2 small apartment sized refrigerators and a microwave after only a few min. on MSW.
I am wondering what would if i connected a capacitor to it.
When i get a chance I will hook up the o-scope and see what happens.
~~~WindriderNM (Electron Recycler)~~~   
~~~Keep Those Electrons Flowing~~~

SparWeb

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #6 on: September 28, 2010, 10:08:58 PM »
fwiw, and ymmv, and all that said first

most all motors, and things that use transformers and relay coils like pure sine wave,
if you power them with modified sine, they will run hotter than they would otherwise on pure sine
and if you feed them with square wave, they will run much hotter

{...}

 folks get all knotted up chasing down a few tenths of an amp
and then burn several extra amps making heat with a modified sine inverter driving a motor load like a refrigerator?

{...}

bob g

Thank you for this explanation, Bob.  That's a great way to put things in perspective.
Successful off-gridders learn to see the system as a whole, not just a piece at a time.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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TomW

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #7 on: September 29, 2010, 05:21:49 PM »
What bob g and sparweb sed...

All the way.

Tom

frackers

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #8 on: September 29, 2010, 05:58:36 PM »
Looks like there is still a bug in the poll part of the board seeing as it has only collected 1 vote in total so far and like others I don't get a set of ticky boxes
Robin Down Under (Or Are You Up Over)

wooferhound

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #9 on: September 29, 2010, 06:41:00 PM »
Well this poll is Locked since it was originated on the old board, should I start a new poll ?
This one has a few missing options I think . . .

JW

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #10 on: September 29, 2010, 06:43:21 PM »
Quote from: frackers
Looks like there is still a bug in the poll part of the board seeing as it has only collected 1 vote in total so far and like others I don't get a set of ticky boxes

I think Wooferhound knows the most about the polls. "I don't get a set of ticky boxes" Woof, if you can determine what he's seeing, I can look into permissions, but am wondering what the difference he's talking about would mean.

On another note, I had to replace the run capacitor on my cental air compressor today for the third time this year, I had to make some modification to the condenser fan, at the second change, but this time I upped the rating from 50 MFD to 60MFD, so far so good.

JW

JW

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #11 on: September 29, 2010, 06:45:26 PM »
Woof,

 I just "unlocked" voting, check to see if that changes things.

JW

JW

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #12 on: September 29, 2010, 07:02:56 PM »
I think all the radio buttons are working now here's a veiw of what im seeing




JW

SteveCH

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #13 on: September 29, 2010, 07:18:36 PM »
Well, locked or not, I've had no trouble with our inverter. As someone said, though, how would know? In our case, we don't know whether damage has been done, but so far, in over 20 yr. of using our Trace mod. sine wave, we've had no failures of anything. Our fridge and freezer are both SunFrost and 12 v., so they don't count. We run a vacuum [Dyson], a flat-screen tv and associated DVD, etc., several Apple computers and peripherals, hand tools, Kitchen Aid and etc. So far, so good. I have been considering a pure sine wave inverter for several yr., but money issues and the continued performance of the old Trace keep me just thinking. Our next one will be pure sine wave, as they are now more commonly available and more reasonable in price than they were back in the 80s, if you could even find one.

wooferhound

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #14 on: September 29, 2010, 10:37:14 PM »
JW
Yes I have control over the locked status of polls. Apparently all the polls that were brought over from the old board were locked in the process. I have unlocked a bunch of the newer ones but I left this one alone since it does not have an option for I don't have an Inverter among others. It is a good subject for a poll though.

frackers

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Re: has a squarewave inverter damaged or shortened the life of your appliances?
« Reply #15 on: September 30, 2010, 03:16:51 AM »
Well - it didn't actually burn down the house but the magic smoke got released from my Kill-O-Watt equivalent as it uses a capacitor to get the low voltage supply for the internal electronics, and while thats fine with a sine wave, a series current limiting resistor went up in smoke when fed modified sine :( (fast edges = low impedance = high current).

Robin Down Under (Or Are You Up Over)

tanner0441

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Hi

The choke hummed and buzzed followed by the rapid failure of the tube in a 60W fluorescent fitting.  I now use a pure sinewave, and keep the 1KW modified for resistive loads only in my camper....

Brian

dnix71

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There should be a "I don't know for sure" box to tick. I didn't vote. I have a couple of mod sine inverters but don't use them. I gave one away and have one that plugs in the dash by Black and Decker. I pay extra for sine wave inverters for home use. One of the smaller mod sine inverters I used to have made a small oscillating fan hum loudly and run slow, so I quit using the inverter and got 12v dc fans instead.

I don't consider it worth the risk to use a mod sine inverter. My washing machine was bought for off-grid use in case that was needed. It has computer controls and cost $450. That's too much money to risk to save a few bucks on the inverter. The inverter that runs the washer is true sine and only cost $260.

HiddenMountain

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Well, aside from a ceiling fan humming we didn't have any trouble with our old Trace 2512 Mod Sine Inverter.

Our washing machine did seem to "fight to find the right gear" with the mod sine though. It has absolutely no problem with the pure sine now.

However, when a friend who was helping me install some roofing plugged in his rechargeable drill, it got cooked and never has worked again.  :-\

As for square wave? Never had the chance to wreck anything with it.  :D
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Madscientist267

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Realizing that I'm coming in way late on this one, I put "minimal damage";

I can second what Frackers brings to the table about capacitive reactance supplies letting the smoke out when run on MSW.

Seen it more than once, a few times actually. My rule now is that if it seems like it might not have a transformer in it (ie  non-switching), then don't use it with an MSW inverter.

Give aways include very small, 'too light', and involve a small capacity battery (internal or external). So this means things like power failure lights (that plug directly into the wall), cordless tool battery chargers, some cell phone chargers, cordless 'guy groomer' tools, cordless toothbrushes (except the inductive type), and so on.

Things that have switch mode supplies in them should be perfectly fine, and may even be slightly more efficient than if run from true sine, depending on the design. Purely resistive loads are no problem. Devices with 'universal' motors in them should not be a problem either, although the sharp edges might cause a little bit of hysteresis heating, but not enough to worry about.

Steve
The size of the project matters not.
How much magic smoke it contains does !