Xantrex 458 Freedom "filtered" modified sine???

[jtad]

I have a Xantrex 458 freedom. Their website says it is a "filtered" modified sine. What is filtered, does it smooth it out to make it operate closer to a pure sine? Their website says it is ok for use with most all appliances, we are thinking about changing over to a res fridge. Is it ok for this?

[Bill_Satellite]

Not when the question is "Will your fridge work with a MSW inverter?"

[msturtz]

Bill.Satellite wrote:
My GE fridge has worked on a 458 MSW for the last 19 years. I don't know if you have a picked a fridge yet but the Samsung units are reported to run well on the MSW unit as well. There are things that won't well but you can always run your genny if necessary. Your fridge should work just fine. Check with the manufacturer to see if their unit will run on a MSW. Just tell them you plan to use it in a solar powered home to avoid the RV confusion.

Solar home systems generally use pure sine inverters. The reason for this is how most of them work. Many MSW inverters create the “negative” 120 v by inserting 120 V positive on the neutral line. This is much easier to do than generating the true negative voltage on the hot line. The problem with this is the required NG (neutral-ground) bond in NEC. A panel NG bond would immediately fry a MSW inverter. So in short telling the appliance manufacturer you have a solar house would communicate that you have a pure sine inverter. That is if they even understand the question.

[jtad]

Thanks for all the info, answered all the questions I had.. We pretty well never boondock.. Mainly just getting from campground to campground we would be on inverter. So we will investigate what is avail for "solar" houses.. Thanks again for all the great info.

[Bill_Satellite]

My GE fridge has worked on a 458 MSW for the last 19 years. I don't know if you have a picked a fridge yet but the Samsung units are reported to run well on the MSW unit as well. There are things that won't well but you can always run your genny if necessary. Your fridge should work just fine. Check with the manufacturer to see if their unit will run on a MSW. Just tell them you plan to use it in a solar powered home to avoid the RV confusion.

[msturtz]

accsys wrote:
We burned up three "smart" toaster ovens before finally switching our Xantrex 458 MSW for a Magnum 2012 PSW - just sayin'. :B

A “smart “ toaster is a great example of what won’t work on a MSW inverter. The reason is simple, it is a high current device so no DC rectifier or switching power supply, it has a line linked zero crossing timer, and sensors, and finally it likely has a poorly filtered simple unregulated power supply for the ASIC circuit board. All this adds up to a short life on MSW power. I would hazard a guess that the tiny capacitors on the board failed cooking the circuit board.

[accsys]

We burned up three "smart" toaster ovens before finally switching our Xantrex 458 MSW for a Magnum 2012 PSW - just sayin'. :B

[msturtz]

To directly answer your question is that any refrigerator that has a single speed AC motor not routed through an inverter will not run well. The reason for this is related to how AC brushless motors work. The AC power interacts with the windings and magnets to turn the motor at a specific RPM. With square wave, including modified sine wave inverters the distorted wave form tries to stop or reverse the motor in mid cycle. This produces heat vibration and unnatural torque forces. All of these are hard on the motor and reduce its efficiency. All filters do is add capacitance to the circuit and potentially shunt wildly out of frequency harmonics. This is effective at reducing the noise in lower quality radio equipment. It won’t help a refrigerator. You can get refrigerators that are certified for MSW (square wave) inverters. Typically they have DC rectifiers and a downstream inverter for precise motor control. Again the speed is dependent on the frequency of the AC power (load dependent). Samsung is a common make that does this.

[JR45]

If you have room for the RF18 Samsung it will run just fine on MSW. I changed out my Xantrex 458 freedom going on 5 years ago with the Magnum 2812 when I installed my Samsung 197. The only reason, I got a good deal on line works great.
My daughter has a 2005 36' Monaco and they installed the Fisher Paykel, more $$$$ but it fit just fine and they have the Xantrex 458 Freedom.
https://www.goedekers.com/Fisher-Paykel-RF170ADX4.html
JR45

[garry1p]

I suspect the "filtered" refers to reducing RF interference that would show up as noise in TV's, DVR, ect. these filters are made up of small capacitors and inductors.

There are some things you can due to round off the output for example filters made from much larger capacitors and inductors but the higher the current output the higher the cost, higher internal heat and a bulkier unit and you still have a MSW just "slightly" cleaner.

You should be able to use a MSW inverter with most refrigerators but not all depends on the manufacture.

[jtad]

I don't know anyone with an oscilloscope.. And buying another inverter is not in the cards the one I mentioned above is whats in the coach and dont want to buy another. Just wondering if it was ok to run a residential fridge with the "filtered" modified wave inverter.

[time2roll]

Get sine wave for a few $$ more and have no worries.

[KD4UPL]

A modified sine wave inverter in the old days was basically a square wave. There could be any manner of filtering done to the wave to make it "closer" to a pure sine wave. Also, there may be any number of "steps" involved in the waveform. The more steps the closer it will resemble and actual sine wave. The less steps the more it will resemble a square wave.
Do you know anyone with an oscilloscope? They could show you a picture of your wave form output.

[Ski_Pro_3]

Filtered most likely refers to the removal of certain harmonics that constitute a square wave. By filtering low order harmonics will round off the corners of a square wave.

Here is a diagram/graph of what is essentially a sine wave, referred to as the fundamental, with the 3rd, 5th, and 7th harmonics added, turning it into a square wave. By removing the harmonics from a square wave, it leaves behind the fundamental frequency that we know as a sine wave.



BTW, most electronics don't mind a modified sine wave. Reason is; the first thing the voltage hits is.... a power supply! Turning the AC into DC voltages. Mostly it's motors that run on AC. Very little electronics run on AC. Look for yourself; see what the firs thing is that the AC goes into. Usually a transformer and a DC power supply or several for that matter as most electronics utilize more than just one voltage. Just like your cell phone. The power supply changes the 120volt AC into 5 volt DC.

[Lwiddis]

“we are thinking about changing over to a res fridge”

And give up dry camping/boondocking without a bunch of batteries and solar or heavy generator use?