UPS to clean MSW?

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Chris
Chris Solar Expert Posts: 135 ✭✭
in Off Grid Solar & Battery Systems #1
Hi guys,

An electrician friend of mine suggested using a UPS (uninterrupttable power supply) to clean power from my MSW inverter. He says they use them at the mill he works at to clean the power feeding the computers.......I haven't came across anything that my inverter wont run yet, but in the spring we plan on buying a new LED tv.......so if I needed to, would this work? if so, would it be very un-efficient?

After having a boo at the staples website looks like I could buy a 300 watter for 75 bucks.
http://www.staples.ca/en/APC-Back-UPS-ES-550VA-8-Outlet-Green-UPS/product_755516_2-CA_1_20001
Or am I just being a cheap arse and should just buy a small SW inverter? LOL
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: UPS to clean MSW?

    There are different types of UPS. Some sit there doing nothing but keeping their batteries charged until need, others "constantly convert": always changing AC IN to DC and back to AC OUT to make sure the power supplied is very clean. They don't do this without using power either.

    But if you are running computers there really is no concern; most computer power supplies will clean up whatever AC signal they receive.

    In short, if your MSW inverter is that bad that the computer is having trouble replace the inverter.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #3
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    Re: UPS to clean MSW?

    There are several ways to clean up modified square waves:

    Motor Generator set (old fashion/expensive/lossy)
    Ferroresonant Transformer (heavy/lots of copper/expensive/lossy)

    And using a continuous conversion UPS. Basically, the AC front end rectifies to DC (charging a battery bank or capacitor bank) and the Inverter back end give you the AC wave form (and you have to double check--Many computer UPS systems are actually MSW output).

    Many/most modern desktop computers work just fine with MSW wave forms (modified square wave). Smaller computers (and electronic devices) many have either transformer or electronic "front ends" that do not work well with MSW wave forms....

    So--If you get a continuous converting inverter with true/pure sine wave output (or a good quality AC to DC power supply+battery+DC to AC sine wave inverter)--you can do what you want. And you have the losses of the extra conversions (and battery losses--if used).

    Or just get a small sine wave 12 VDC input inverter and run that... MorningStar 300 watt TSW inverter is really nice, plus includes a remote on/off switch and "standby mode". Or a small Samlex TSW inverter.

    Wire up your system to run small loads and keep the 3kWatt monster for the big loads. Should be a good solution (efficient and not too costly, does not add another AC to DC to AC conversion).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bill von novak
    bill von novak Solar Expert Posts: 891 ✭✭✭✭
    #4
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    Re: UPS to clean MSW?
    Chris wrote: »
    An electrician friend of mine suggested using a UPS (uninterrupttable power supply) to clean power from my MSW inverter. He says they use them at the mill he works at to clean the power feeding the computers.......I haven't came across anything that my inverter wont run yet, but in the spring we plan on buying a new LED tv.......so if I needed to, would this work? if so, would it be very un-efficient?

    Cheap UPSes will not clean up the power. More expensive UPSes will convert AC to DC via a charger, then DC back to AC via an inverter. They are inefficient (two conversion steps) as well as expensive.

    Rather than buy a new charger, battery set and inverter it would likely make more sense to just buy the sine wave inverter.
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  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    #5
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    Re: UPS to clean MSW?

    Thanx for the reply's guys

    Like I said, I don't have anything out at the lake that my inverter won't run at the moment (runs my little LCD TV and DVD player just fine). Wile talking with my buddy I mentioned that I was thinking of picking up a small SW inverter and this came up, I had a feeling that it would be a power sucker....but had to ask as I thought maybe I stumbled on to something here LOL.

    Being winter I'm not going out to the trailer very often other then the occasional over night trip just to check on things......but I'm spending alot of time dreaming up ways to improve the system.

    Now I know this cheap Can Tire inverter isn't the greatest but it seems to work fine for me for now.....has anyone used these? are there any other draw backs to them other then being MSW? the book says it self consumes .4 of an amp is that comparable to others?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: UPS to clean MSW?

    I actually tested a whole range of Canuck Tyre's inverters a few years back. Every one of them failed to meet the power rating. But that was then and this was now: like so many other retailers the things sold under their brand are contracted out. In other words whichever company made the inverters then may not be who makes them now, and the design/specs may have changed.

    As far as self-consumption is concerned, this will vary with the size of the inverter as well as the manufacturer and model. 0.4 Amps @ 12 Volts is pretty good for standby consumption. (Pure sine inevitable consumes more power, btw.)

    If it's working for you, don't worry about it. When you add the A/V equipment they may pick up the noise of the MSW and then you'll want something 'cleaner' to power that.
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  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    #7
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    Re: UPS to clean MSW?

    Thanx Coot,

    Good to know bout the self consumption......I've always been paranoid about that.....if nothing is running it's off immediately.

    So I could comfortably leave it running wile we are at the lake?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
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    Re: UPS to clean MSW?

    So long as the inverter consumption for the time it is on is factored into the calculations for sizing the battery bank it can be left on. People often make the mistake of leaving this out, and in some cases it can be quite a hefty amount of power in a day.
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  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    #9
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    Re: UPS to clean MSW?

    Ok, so this might be a dumb question, but this .4 of an amp.....do I calc that off the 110 side or the 12? ei .4 X 110= 44 watts, or .4 X 12= 4.8 watts?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
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    Re: UPS to clean MSW?

    The inverter draws from the batteries, so it's 0.4 Amps @ 12 Volts.

    The full calculation would be:

    AC Watt hours / inverter efficiency = DC Watt hours
    Add inverter Watts * time on to get total DC Watt hours
    Divide by nominal system Voltage to get approximate Amp hours used
    This should be multiplied by 4 to get Amp hour capacity of the battery bank for 25% DOD
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #11
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    Re: UPS to clean MSW?
    Cariboocoot wrote: »
    I actually tested a whole range of Canuck Tyre's inverters a few years back. Every one of them failed to meet the power rating. But that was then and this was now: like so many other retailers the things sold under their brand are contracted out. In other words whichever company made the inverters then may not be who makes them now, and the design/specs may have changed.

    As far as self-consumption is concerned, this will vary with the size of the inverter as well as the manufacturer and model. 0.4 Amps @ 12 Volts is pretty good for standby consumption. (Pure sine inevitable consumes more power, btw.)


    I recently got a 1,500 watts PSW inverter from eBay - $156 USD, shipping included to Cambodia. I was surprised to win the auction a that rate, honestly. (It cost the shipper $30 USD, via DHL, to get it to me.) Anyway, after it arrived I tested it. 0.4 ampere draw at 12vdc, on standby.
    Paul
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #12
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    Re: UPS to clean MSW?
    ILFE wrote: »
    I recently got a 1,500 watts PSW inverter from eBay - $156 USD, shipping included to Cambodia. I was surprised to win the auction a that rate, honestly. (It cost the shipper $30 USD, via DHL, to get it to me.) Anyway, after it arrived I tested it. 0.4 ampere draw at 12vdc, on standby.

    Did you put a scope on it? Or did you just accept the seller/maker's claim that it is pure sine wave?

    Beware that equipment can be labeled "pure sine wave" (or "MPPT" on controllers) and not be so: there are an awful lot of liars out there.
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  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    #13
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    Re: UPS to clean MSW?

    Also theres some frightening excuse for electronics inside some of those cheap units. Very little in the way of circuit protection. My advice would be to always use such things under supervision. If you value your sleep/peace of mind, anyway. Unfortunately inverters are one thing that you pay for you what you get, no exceptions.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #14
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    Re: UPS to clean MSW?
    Cariboocoot wrote: »
    Did you put a scope on it? Or did you just accept the seller/maker's claim that it is pure sine wave?

    Beware that equipment can be labeled "pure sine wave" (or "MPPT" on controllers) and not be so: there are an awful lot of liars out there.

    Finding a scope here would be next to impossible. Electric motors don't "like" MSW inverters. That is the only immediate way that I could test it.
    Paul
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #15
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    Re: UPS to clean MSW?
    zoneblue wrote: »
    Also theres some frightening excuse for electronics inside some of those cheap units. Very little in the way of circuit protection. My advice would be to always use such things under supervision. If you value your sleep/peace of mind, anyway. Unfortunately inverters are one thing that you pay for you what you get, no exceptions.

    Granted, I am sure it was made in China. But, are there inverters today, that are made elsewhere, with better circuitry?
    Paul
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #16
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    Re: UPS to clean MSW?

    Even though AC induction motors don't 'like' MSW they will usually run on it.

    There are inverters made in China that aren't junk; it has more to do with the company's concern with their reputation for quality than anything else. The El Cheapo ones can go out of business, change their name, and start up again selling the same junk.

    There's more than one way to make an inverter. ;)
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #17
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    Re: UPS to clean MSW?

    Agreed. I have run electric motors off known MSW inverters here, before. They would make a horrible humming noise.

    I don't notice that same noise when I plug them into this particular inverter. They run exactly as they do when plugged into a mains power point.

    It's the best test I can put it through, considering the circumstances.
    Paul
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #18
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    Re: UPS to clean MSW?
    ILFE wrote: »
    Granted, I am sure it was made in China. But, are there inverters today, that are made elsewhere, with better circuitry?

    A lot of the "junk" chinese inverters have great circuitry... they copy (sometimes steal) it from high quality inverters. The reason they are junk is because of low quality components and assembly.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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