Samsung and LG refrigerators on a modifies sine wave inverter

fhillier · May 2018

My setup has a Modified sine wave inverter and can't afford to change it right now and want to add a refrigerator. The LG and Samsung have been recommended. Any comments about longevity also will I need a line conditioner because of the Modified?

jonr · May 2018

My guess is that an inverter based refrigerator is a good match for a MSW inverter, with no reduction in longevity.

mike95490 · May 2018

Line Conditioners work poorly with MSW inverters, because it's not just a little bit of cleanup that needs to be done.

MSW inverters are poorly named, they are Square wave inverters and bear little resemblance to a sine wave.

mcgivor · May 2018

Square wave is problematic with many electronic devices, switching transformers for example, due to the abrupt changes in voltage, capacitors are particularly vulnerable to the extreme rise and fall, being their responsibility of smoothing the incoming waveform. The voltage rises too quickly, then collapses before the circuitry can respond, causing the device to hunt, which in return results in stress and premature failure. This phenomenon is also problematic in induction motors, which manifests as heat buildup in the laminated cores. For these reasons my opinion/recommendation is only use modified sine wave for restive loads, even an inverter refrigerator, which needs to rectify the incoming waveform could potentially have problems, perhaps not immediately but over time, which supports @mike95490 statement regarding line conditioninors.

706jim · May 2018

I went through this process last year after buying an Insignia fridge from Best Buy. Even bought a Samlex pure sine inverter to run it only to find that I ordered the wrong voltage. So I took a chance and hooked it up to my old Trace MSW inverter. The fridge has been fine after about 3 months continuous operation despite running with a power factor of 45-60%.
Time will tell if there will be a problem with MSW power, but it has worked just fine for my TV satellite receiver induction motor powered water pump and nearly everything else. It has been mentioned here that the Trace DR inverters are a"better" version of MSW power possibly due to its transformer design.
Once again it comes down to "should I buy a $1500 inverter to save a $400 fridge"?

Estragon · May 2018

I suspect there are significant differences in MSW inverters. Some may be nearly square wave with the very sudden voltage changes @mcgivor noted above, while others change voltage in a series of steps. Although a stepped wave isn't a curve like a sine wave, it could be a reasonable approximation with enough steps.

I started out at the cabin using a cheap (1500w IIRC) MSW inverter from a hardware store. It weighed maybe a couple of pounds. The Xantrex MSW 2000w inverter on my boat isn't a whole lot smaller or lighter than my 3500w Outback PSW. The Xantrex includes charging as well as inverting, but I don't think that accounts for the extra size and weight.

mcgivor · May 2018

Yes I blanketed all modified sine wave inverters, some are better than others, some with a stepped sine wave, but then again some "pure" sine wave are not much better with high "THD" or total harmonic distortion, guess it's a point of good not cheap, cheap not good.

Samsung and LG refrigerators on a modifies sine wave inverter

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