Question:
> After this experience, I will *never* plug anything in to an > inverter that do not give a pure sine wave! No modifications!
Understandable. The question then becomes, how do you define a "pure sine wave?" The common standard is by the percentage of Total Harmonic Distortion (%THD). But it seems to me that some distortion could easily be worse than other… Most sine wave inverters today, generate a sine wave via a multi-step approximation. Trace SW inverters with up to 50-some steps claim THD under 5%, yet are very jagged compared to others which use 400-some steps. The fewer steps the lower the frequency of noise created and the more steps the higher the frequency. Some noise filters may filter the frequency produced by the Trace, and others may not. If you have a noise filter in the power supply of some equipment, and that filter happens to filter out the noise frequency of your inverter, then the quantity of noise becomes important. Too much noise, *POOF* goes the filter. But the same amount of noise at a different frequency might be fine. No way to know… I bought a Trace SW. So far nothing has complained. sdb — More guns means less crime. ISBN:0-226-49363-6 *** IWant: Song of the South video — any digital format *** Watch out for munged e-mail address. User should be sdbUse1 and host is at bigfoot.com Do NOT send me unsolicited commercial e-mail (UCE)!
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Hi I’m off-grid in the UK with 24v and a Trace 1524 24v modified sine wave. All the items you list work fine with it (I use them all) but it has proved: – sensitive to nearby lightning strikes (so invest in good grounding if you get much lightning) – difficult to repair (after lightning) – the answer is always to replace a module which tend to cost half of what the inverter cost – noisy – I put it inside the house as they advised to treat it it like a hi-fi – mistake -buzzes like hell – there’s some buzzing at 50hz from compact flourescent lights – perhaps motors start a little slower If I were starting out again (or richer) I’d go for a sine wave inverter there’s a Swiss company call Studer seem to make interestingly cheap inverters with guaranteed silent operation. It’s perverse as I’ve had 3 years successful experience but it’d be nice to be able to buy some flashy hi-fi equipment without the feeling that you MIGHT damage it with the wave form. Ta Mick Wilcox "ER to reply to my e-mail address remove (nospam)."
– Hide quoted text — Show quoted text -> Just a few quick questions… > 1. Is a modified square wave inverter the same as a modified sine wave > inverter? > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights > I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 > Hz. > Finally – I’m looking at helping some friends set up a small stand-alone > wind/solar setup. I was looking at using 48V as the primary DC voltage as we > may have to run a lot of DC wiring (48VDC will reduce resistance losses). > Now, I know that it will be harder to find 48VDC equipment (inverters and > regulators), but what are the advantages of running 48VDC compared to 24/12 > VDC, aside from the lower resistance losses? > Ta, > Ewan
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www.mgeups.com ,try this – Hide quoted text — Show quoted text – >To Screecheagle: I’m kinda new here. Any chance you have a web site >(URL) for MGE? I’ll try a search on Powermark. >Thank You, >Matt Zilmer >>Just a few quick questions… >>1. Is a modified square wave inverter the same as a modified sine wave >>inverter? >>2. What’s the limitation of using a modified square wave inverter when it >>comes to using the following appliances: >> a. personal computers >> b. televisions >> c. microwaves >> d. electric motors >> e. flourescent lights >>I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 >>Hz. >>Finally – I’m looking at helping some friends set up a small stand-alone >>wind/solar setup. I was looking at using 48V as the primary DC voltage as we >>may have to run a lot of DC wiring (48VDC will reduce resistance losses). >>Now, I know that it will be harder to find 48VDC equipment (inverters and >>regulators), but what are the advantages of running 48VDC compared to 24/12 >>VDC, aside from the lower resistance losses? >>Ta, >>Ewan >48V is a fine way to go.may i suggest a Powermark inverter,available >from MGE.they are made in the U.S.,but are selectable to >50Hz.available in 1,5,and 10KVA sizes,they are quiet(at least the >newer ones)and efficient.the output is as close to a true sine as you >will see from any inverter(<4%THD). > BTW,i don’t work for MGE,but i used to.i was a specialist in this >line,and loved working on them as there was never much to do. > hope this is of some help…….cheers
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– Hide quoted text — Show quoted text -> Just a few quick questions… > 1. Is a modified square wave inverter the same as a modified sine wave > inverter? > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights > I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 > Hz. > Finally – I’m looking at helping some friends set up a small stand-alone > wind/solar setup. I was looking at using 48V as the primary DC voltage as we > may have to run a lot of DC wiring (48VDC will reduce resistance losses). > Now, I know that it will be harder to find 48VDC equipment (inverters and > regulators), but what are the advantages of running 48VDC compared to 24/12 > VDC, aside from the lower resistance losses? > Ta, > Ewan
1. Is there a definition of these terms? I have an inverter, Genius Power G12080 that is supposed to output "modified square wave" according to the specs. On the scope I see this: +280V — +—-+ | | | | 0 V —- –+ +—+ +—+ | | | | | -280V — +—-+ A bit more detailed picture is here: http://www.geocities.com/bo_siltberg/omvandlare1.pdf 2. The above inverter loaded with a battery charger with a switchmode power supply (320W) gave current spikes like this: +30 A — | | | | | | | | | | | | | | | | -30 A — | Neither the inverter or the battery charger liked it. The charger gave a buzzing sound and the inverter shut off now and then. A hand-held drilling machine also shut off the inverter sometimes. A ground-fault circuit interrupter blew up. The situation became much better after putting a coil of 8mH and a resistor of 22 ohm in serie with the battery charger. The following picture shows the effect with only the coil in series: http://www.geocities.com/bo_siltberg/omvandlare2.pdf With both the coil and resistor, the voltage looked fine, a square wave with no ringing. Of course, the voltage dropped, but still 205V over the battery charger. The current is somewhat like a sine wave but with alot of ringing/ripple. At least, there are no spikes of 30A any longer. After this experience, I will *never* plug anything in to an inverter that do not give a pure sine wave! No modifications! I would really like to hear any comments from the manufactures of these modified-square-wave-inverters. I have not found any warnings that some equippment may blow. On the other hand, the sales litterature for sine wave inverters says that it "works much better for some types of load"… I think they could motivate the extra (alot extra) cost much better. The bottom line is, what can I feed with "modified square wave"? Is it 100% safe to test and plug in my $$$$ VCR? (no other effects than triggering some protection circuit (that is possible to reset)) Bo
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To Screecheagle: I’m kinda new here. Any chance you have a web site (URL) for MGE? I’ll try a search on Powermark. Thank You, Matt Zilmer – Hide quoted text — Show quoted text ->Just a few quick questions… >1. Is a modified square wave inverter the same as a modified sine wave >inverter? >2. What’s the limitation of using a modified square wave inverter when it >comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights >I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 >Hz. >Finally – I’m looking at helping some friends set up a small stand-alone >wind/solar setup. I was looking at using 48V as the primary DC voltage as we >may have to run a lot of DC wiring (48VDC will reduce resistance losses). >Now, I know that it will be harder to find 48VDC equipment (inverters and >regulators), but what are the advantages of running 48VDC compared to 24/12 >VDC, aside from the lower resistance losses? >Ta, >Ewan >48V is a fine way to go.may i suggest a Powermark inverter,available >from MGE.they are made in the U.S.,but are selectable to >50Hz.available in 1,5,and 10KVA sizes,they are quiet(at least the >newer ones)and efficient.the output is as close to a true sine as you >will see from any inverter(<4%THD). > BTW,i don’t work for MGE,but i used to.i was a specialist in this >line,and loved working on them as there was never much to do. > hope this is of some help…….cheers
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– Hide quoted text — Show quoted text – >Just a few quick questions… >1. Is a modified square wave inverter the same as a modified sine wave >inverter? >2. What’s the limitation of using a modified square wave inverter when it >comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights >I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 >Hz. >Finally – I’m looking at helping some friends set up a small stand-alone >wind/solar setup. I was looking at using 48V as the primary DC voltage as we >may have to run a lot of DC wiring (48VDC will reduce resistance losses). >Now, I know that it will be harder to find 48VDC equipment (inverters and >regulators), but what are the advantages of running 48VDC compared to 24/12 >VDC, aside from the lower resistance losses? >Ta, >Ewan
48V is a fine way to go.may i suggest a Powermark inverter,available from MGE.they are made in the U.S.,but are selectable to 50Hz.available in 1,5,and 10KVA sizes,they are quiet(at least the newer ones)and efficient.the output is as close to a true sine as you will see from any inverter(<4%THD). BTW,i don’t work for MGE,but i used to.i was a specialist in this line,and loved working on them as there was never much to do. hope this is of some help…….cheers
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I’m in an outer eastern suburb of Perth, Where in Ozzieland are you? That we may discuss these matters in the correct context. – Hide quoted text — Show quoted text – >Just a few quick questions… >1. Is a modified square wave inverter the same as a modified sine wave >inverter? >2. What’s the limitation of using a modified square wave inverter when it >comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights >I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 >Hz. >Finally – I’m looking at helping some friends set up a small stand-alone >wind/solar setup. I was looking at using 48V as the primary DC voltage as we >may have to run a lot of DC wiring (48VDC will reduce resistance losses). >Now, I know that it will be harder to find 48VDC equipment (inverters and >regulators), but what are the advantages of running 48VDC compared to 24/12 >VDC, aside from the lower resistance losses? >Ta, >Ewan
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>Just a few quick questions… >1. Is a modified square wave inverter the same as a modified sine wave >inverter?
Pretty much. The way the modified sine wave is derived is from a square wave. It comes out a dual polarity RTZ waveform. The cost of an MSW inverter is generally quite a bit lower than a true sine wave inverter. You might be able to run your home on MSW, but you will not be allowed to grid tie, at least in the US. >2. What’s the limitation of using a modified square wave inverter when it >comes to using the following appliances: > a. personal computers
No problems known since the switching supply in desktop machines pretty much takes any type of AC. The CRT might be affected a bit, though I haven’t had this problem. Since most laptops use transformer supplies, you might get a bit more heating in these. > b. televisions
Buzzing in the audio, though this is not extreme. > c. microwaves
No problems. Sometimes the clock/timer might be unhappy. > d. electric motors
Generates more heat than with pure sine because of the additional harmonics in the waveform. Also true in transformer cores. > e. flourescent lights
I’ve heard of folks having trouble getting some of them to start with MSW. Our cheap ones at home are fine. >I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 >Hz. >Finally – I’m looking at helping some friends set up a small stand-alone >wind/solar setup. I was looking at using 48V as the primary DC voltage as we >may have to run a lot of DC wiring (48VDC will reduce resistance losses). >Now, I know that it will be harder to find 48VDC equipment (inverters and >regulators), but what are the advantages of running 48VDC compared to 24/12 >VDC, aside from the lower resistance losses?
Your main advantage is the wire size. It’s also possible that you may save a couple bucks on breakers, provided current levels are low enough to make a difference on pricing. Matt Zilmer – Hide quoted text — Show quoted text ->Ta, >Ewan
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Not all pure sign wave inverters are created equal! I am running a Statpower Prosine 1800 " True Sine Wave Power Inverter" and have like problems.It runs all electronics fine, computer, entertainment system, CFs, and ham radio equipment are all ok. It will run inductive loads, but not well. My older refrigerator gets hot and shuts down, the dehumidifier runs slower. It can start the loads fine but it will not run them at normal speed. I also run a Matag Neptune washer with out problem as long as I have a light on to keep the inverter out of power save mode. For this system to pay for its self I need to run my refrigerator, any one have an "off the shelf" energy efficient unit to recommend? kwd/KE9CS http://users.wwt.net/~dicksk/ – Hide quoted text — Show quoted text -> runs fine on the modified sine wave as > long as the battery voltage is above 12.5, (I use a 12 volt system as I use > redundant 12 volt inverters). If teh voltage from the source (battery) is less > than around 12.5, say 12.4 or 12.3 then the inverter’s modified square wave is > modified further and the frezer gives up. It is not the inverter, other things run > fine at that time, it is the freezer. When I switched the freezer to a sine wave, > then that was the end of my trouble. Of course the sine wave inverter does what it > needs to do t maintain voltage, but the moral is simple, sine wave works always, > modified square wavr, most of the time.
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> The modified square wave is a stepped square wave, that is an improvement over > a non-stepped square wave in that it is less reactive with inductiveloads. It > is a compromise between a pure square wave and a sin wave. > I am running a Statpower Prosine 1800 " True Sine Wave Power Inverter" and > have like problems.It runs all electronics fine, computer, entertainment > system, > CFs, and ham radio equipment are all ok. …. any one have an "off the shelf" > energy efficient unit to recommend?
A couple of points… I was hoping that the DR1512 would use a stepped square wave. In looking at it on the scope, It has a rapid rise, then a lot of noise on the high voltage line, then a descent to repeat the process. Modified square waveshould be as the earlier comment said, and maybe it is just my DR1512 that is out of wack. On the Prosine 1800 and the fridge, I use a Prosine 1000 for the deep freeze and the Prosine 1800 for the fridge, and they work well. I am getting a Prosine 3000 to replace the Prosine 1800 which will become a backup, the reason being to add more loads from the house. The two Prosine’s I currently have seem to behave very well, I hope you will consider returning your under warranty. I HAVE HEARD that some Prosine’s have problems returning to search mode, but as of yet I have been happy with them. I also have an Exeltech XP600/12 with which I am happy. Simon WB7ULT, G3ROW
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>It will run inductive loads, but not well. My older refrigerator gets hot and shuts >down, the dehumidifier runs slower. It can start the loads fine but it will not run >them at normal speed. I also run a Matag Neptune washer with out problem as long as I >have a light on to keep the inverter out of power save mode. >For this system to pay for its self I need to run my refrigerator, any one have an >"off the shelf" energy efficient unit to recommend?
My SW5548’s in a stacked series configuration run all of my appliances without any funny sounds or detectable problems. Includes Neptune washer/dryer, refrig, dishwasher, microwave, stereo, tv, computer, satellite systems, fans, pumps, etc. I don’t use search mode, however, due to low power constant-on equipment (security system; motion sensor lights; garage door openers). Best, –ron
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– Hide quoted text — Show quoted text -> Just a few quick questions… > 1. Is a modified square wave inverter the same as a modified sine wave > inverter? > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights > I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 > Hz. > Finally – I’m looking at helping some friends set up a small stand-alone > wind/solar setup. I was looking at using 48V as the primary DC voltage as we > may have to run a lot of DC wiring (48VDC will reduce resistance losses). > Now, I know that it will be harder to find 48VDC equipment (inverters and > regulators), but what are the advantages of running 48VDC compared to 24/12 > VDC, aside from the lower resistance losses? > Ta, > Ewan
To answer your questions point by point. 1. No 2. a. I have used a personal computer on a Trace 2512 (modified square wave) without problems, but that may or may not apply to all computers. b. My television works OK but again only a sample of one. c. Microwave works OK but will be a bit slower to heat items. d. Electric motors (induction type) all seem to work OK. e. For fluorescent lamps the ballast is often noisy due to the sharp corner on the square wave. In this case the 50 vs the 60 Hz that I use may make the noise problem worse. Also the inverter itself makes some noise I am in the process of moving mine partially for that reason. These answers are based on using both Trace 1512 and 2512 over about 6 years. Jack
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2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. fluorescent lights
The modified square wave is a stepped square wave, that is an improvement over a non-stepped square wave in that it is less reactive with inductive loads. It is a compromise between a pure square wave and a sin wave. It is not predictable, the results you will get with the listed appliances, because of the variety of reactances you would encounter. I found that my 140 watt inverter would not operate one compact fluorescent but did another. Televisions that have no isolation transformer should work. Fans with induction motors can have low torque. Dave M. "ER to reply to my e-mail address remove (nospam)."
– Hide quoted text — Show quoted text -> Just a few quick questions… > 1. Is a modified square wave inverter the same as a modified sine wave > inverter? > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > c. microwaves > d. electric motors > e. flourescent lights > I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 > Hz. > Finally – I’m looking at helping some friends set up a small stand-alone > wind/solar setup. I was looking at using 48V as the primary DC voltage as we > may have to run a lot of DC wiring (48VDC will reduce resistance losses). > Now, I know that it will be harder to find 48VDC equipment (inverters and > regulators), but what are the advantages of running 48VDC compared to 24/12 > VDC, aside from the lower resistance losses? > Ta, > Ewan
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- Hide quoted text — Show quoted text -> 1. Is a modified square wave inverter the same as a modified sine wave > inverter? > yes – for your purposes > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions > "buzzing" from CRT > c. microwaves > digital clock might be inaccurate > d. electric motors > might run warmer > e. flourescent lights > not sure
I agree with the above. Additionally, the modified square wave (as that is what it is, it never ever was a sine wave that wasmodified) may interact in unpredictable ways. For example, a deep freeze I have wuns fine on the modified sine wave as long as the battery voltage is above 12.5, (I use a 12 volt system as I use redundant 12 volt inverters). If teh voltage from the source (battery) is less than around 12.5, say 12.4 or 12.3 then the inverter’s modified square wave is modified further and the frezer gives up. It is not the inverter, other things run fine at that time, it is the freezer. When I switched the freezer to a sine wave, then that was the end of my trouble. Of course the sine wave inverter does what it needs to do t maintain voltage, but the moral is simple, sine wave works always, modified square wavr, most of the time. Another problem area for modified aquare wave is the non transformer power supplied units. Such as my mtion detector lights. After a month of modified square wave, they became "shrimps on the barbie". They were fired. Now I use sine wave for everything, and reserve modified square wavr for the well pump and pressure pump and shop tools. On the issue of efficiency, a point to consider is that inverter efficiency versus the appliance and just how much of the modified square wave it can use. In other words, a highly efficient modified square wave and a slightly less efficient sine wave may in fact results in appliance usage such that the less efficient sine wave was better used than the modified square wave. For long cable runs, the higher the DC voltage the better. The suggestion to invert is a good one. I have only two DC loads, the rest are AC. Just a few points to think about. Simon
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Just a few quick questions… 1. Is a modified square wave inverter the same as a modified sine wave inverter? 2. What’s the limitation of using a modified square wave inverter when it comes to using the following appliances: a. personal computers b. televisions c. microwaves d. electric motors e. flourescent lights I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 Hz. Finally – I’m looking at helping some friends set up a small stand-alone wind/solar setup. I was looking at using 48V as the primary DC voltage as we may have to run a lot of DC wiring (48VDC will reduce resistance losses). Now, I know that it will be harder to find 48VDC equipment (inverters and regulators), but what are the advantages of running 48VDC compared to 24/12 VDC, aside from the lower resistance losses? Ta, Ewan
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> Just a few quick questions… > 1. Is a modified square wave inverter the same as a modified sine wave > inverter?
yes – for your purposes > 2. What’s the limitation of using a modified square wave inverter when it > comes to using the following appliances: > a. personal computers > b. televisions
"buzzing" from CRT > c. microwaves
digital clock might be inaccurate > d. electric motors
might run warmer – Hide quoted text — Show quoted text -> e. flourescent lights not sure > I’m in Australia so the output I’d be looking at using would be 240 VAC, 50 > Hz. > Finally – I’m looking at helping some friends set up a small stand-alone > wind/solar setup. I was looking at using 48V as the primary DC voltage as we > may have to run a lot of DC wiring (48VDC will reduce resistance losses). > Now, I know that it will be harder to find 48VDC equipment (inverters and > regulators), but what are the advantages of running 48VDC compared to 24/12 > VDC, aside from the lower resistance losses? > Ta, > Ewan
48VDC appliances are expensive, and there aren’t many suppliers. I’ve found that most suppliers of low-voltage appliances have 12 and 24 volt versions of most of their inventory, but only a few 48 volt appliances. I run 24VDC for lighting & refrigeration, with 240VAC provided by a "true" sine wave inverter, for the computer, TV & washing machine. Works for me, YMMV. If the "lot of DC wiring" means that your wind generator will be some distance from the batteries/house/appliances, then you should consider inverting the entire supply from low-voltage DC (whatever you choose that to be) to 240VAC at the source, then run everything on 240VAC. — Bernie Dwyer dump the z before replying
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