Power Factor Correction

[PAToyota]

Ok, I understand the basics of power factor correction - used on single-phase, constant current power sources, to reduce the amount of primary amperage demanded from the power company while welding.

For my Syncrowave 250DX it will cost about $350 to $400 for the package and reduce the required breaker size from 125amp to 80amp. I can accommodate it either way, but have not really been able to receive a clear answer either way on whether it is worth doing.

Any thoughts?

[smithboy]

Isnt the reason they have this option simply to reduce the breaker size required and to lower the power demand? I wouldn't think it's worth it if you already have the breaker capacity, unless other tools may push you over the total amps for the service panel. I dont think the reduction in power demand will not pay off in lower power bills either, unless you run the holy heck out of it for a long time. There are some electricians here...maybe they will chime in on this...

[PAToyota]

That is basically my question. If they are telling me changing from a 100watt (.83amp) bulb to a 60watt (.5amp) bulb in my light fixtures is going to save $$ over the course of a year it would seem that drawing 80amp instead of 125amp is going to save significantly more... (and I fully realize that I'm very, very rarely getting anywhere close to maximum on this machine).

But for the most part I keep getting people telling me that I'm not going to save any electricity...

[smithboy]

There was a discussion about how much a mig machine used, cause someone had a dispute about a power bill. Most everyone concluded that unless you are doing a bunch of continuous welds, welders tend not to cost very much to run at all. I, for instance, had a few days during the summer (july to be exact) where I was welding as continuous as a stick welder would allow for many hours a day. I never got above the minimum charge on my electric bill for that month. I have only once exceded the min. and that was when I had a fridge go bad and start running the compressor night and day. Sandy, I think, was the one that did the computation for the cost of running a welder. You might want to send him a personal message, just to get the low down. BTW, he tends to answer the electrical questions, so he might get here and post before you send the message.

http://www.weldingweb.com/showthread.php?t=3456

here is the thread I was talking about.

[PAToyota]

Thanks for the link. Sandy's calculations over there pretty much throw the cost savings of the power factor correction out the window.

I'm thinking that there is a reason that you never tend to run across a machine WITH power factor correction in it... :)

[falconblack]

I think it is worth getting and you will save.If you use the basic consumption formula you will see the difference.It is as follows:Take your voltage times it by your amperage and that will equal wattage used.Divide by 1000 and that is Kilowatts used.Kilowatts are what the power company charges you on;ie .05 per kilowatt used.So if you take 240 volt X 125 amps=30000 /1000 =30Kilowatts x .05 per kilowatt=$1.50 if you do the same for 80 amps it is 240x80=19200 /1000=19.2 x .05=0.96 a difference of .54 cents which does not take long to add up if you are doing a fair bit of welding.

[Sandy]

So if you take 240 volt X 125 amps=30000 /1000 =30Kilowatts x .05 per kilowatt=$1.50 if you do the same for 80 amps it is 240x80=19200 /1000=19.2 x .05=0.96 a difference of .54 cents which does not take long to add up if you are doing a fair bit of welding.

Are you working with input amps of 125 ? That's a heafty input demand for the class of welders most of us lil guys are used to. TIGs maybe get closer to that than the average small shop stick or mig. And then how much actual arc time you going to have at 125 amps input?

And for fun let's say you were using the 240 volt input at 80 amps input for the total of 19.2 Kwatts hours per hour of trigger time, with PFC you would only realize maybe (wild guess) 2 cents per Kilowatt hr savings. That would be around 38 cents saving for every solid hour of 80 amp input running.

The reason I say 2 cents per KWhr savings is because us lucky folks in kalifornia where they deregged the power are now payiong about 11 cents per now. PFC only saves you the difference between an estimated Pf of maybe .85 and an ideal 1.0.

Another real question someone could answer here is what is the average power factor for lets just say a plain DC 225 amp stick welder. Then you would have some more valid numbers to work with. My numbers here are just guestimates for discussion purposes. I don't care to put a lot into it because PFC is right up there with running with your tail gate down as far as I'm concerned. There are, tho, other real valid reasons for PFC which have more to do with current on demand than savings.

But I do agree, savings is savings. So if you had a full time shop and ran several hours (arc time) a day six days a week there just might be something there to look at.

[PAToyota]

I agree with Sandy. I'm probably using the TIG a couple weekends a month, so it just doesn't add up to that much even if I'm out there all day for those two or three days a month. I'll spend more money on the couple beers I have after that long day... :)

[TxRedneck]

Ok, so can anyone answer me this one...If I lets say want to run a machine off my bobus its a 10KW generator. Lets say its a sync 200 tig welder. Would I be better off with the power correction or not? Ive heard some say yes and some say no and no real diffenitive explanation though to back either. I am to understand on shop wiring the PFC might be beneficial...but what about my bobus?

[smithboy]

I'm with you, chris. The more I read about the feature the less I think I really understand about it. I have read from the manufacturers that PFC reduces current draw, so you can lower the breaker size and reduce energy consumption. That would seem to mean you could run a PFC welder on a generator easier than a non-pfc welder, right? I have also read that PFC causes the draw at idle to be higher than the same welder without it because of the capacitors. If that is true, your wiring would have to be sized for a higher duty cycle since the outlet will think the welder is on-duty all the time. Additionally, wouldnt that mean a higher work load for a generator for a PFC welder during periods of no welding? Maybe this is what you have seen also.

It seems like if this were a universally beneficial option for home users, it would be heavily marketed that way. However, all the stuff I see seems geared toward the industrial user...for example, you don't see PFC as an option on smaller consumer-targeted welders...only on bigger ones...often tig machines, because of thier dependence on single phase power and their use of AC welding for aluminum.

Here is my non-technical take on the info...

If you are welding at close to the welder's duty cycle, PFC can help reduce both TOTAL power consumption and necessary breaker size. But, if you have lots of idle time, you may actually increase the MARGINAL power consumption at idle, and possibly the TOTAL power consumption for a home user (if he has lots of idle time with the welder running), and force the home user to improve the wiring to the point of handling the entire duty cycle of the welder, instead of allowing him to just get by with lower rated stuff as long as he doesnt approach the duty cycle of the welder.

Someone jump in here and correct me if you see anything wrong with what I have written. I bet many folks here would appreciate some expert testimony on this subject. Right now, I am just using a bit of reasoning to get to the conclusions above...not a working knowledge of the physical/electrical processes involved.

I am often shocked by my lack of knowledge on the subject of electricity....:)

[PAToyota]

I am often shocked by my lack of knowledge on the subject of electricity....:)

Careful there! :laugh:

[Sandy]

Here is my non-technical take on the info...

If you are welding at close to the welder's duty cycle, PFC can help reduce both TOTAL power consumption and necessary breaker size. But, if you have lots of idle time, you may actually increase the MARGINAL power consumption at idle, and possibly the TOTAL power consumption for a home user (if he has lots of idle time with the welder running), and force the home user to improve the wiring to the point of handling the entire duty cycle of the welder, instead of allowing him to just get by with lower rated stuff as long as he doesnt approach the duty cycle of the welder.

Dang, sounds good to me.:) One small clarification on the home user side, and I think it's what you meant any way----------the TOTAL power consumption during the idle state is not actually consumption of the meter moving billable type but is definitely measurable current flow back and forth. That being what it is does take a circuit out of the exception category for such things as welders and puts it in the constant duty category, causing the wiring upgrades you talked of.. Right--wrong--close???

Just my take from my limited ability to decipher electric guru talk.

[falconblack]

Sandy .97-2.00 is 15 percent savings and also most people use their welder to the max alot of the time so breaker and wire size comes into play.Hence you can never have a big enough machine.....lol that is why we all upgrade to bigger never smaller.If we got extra power we will find a way to use it,right?Right or wrong that is my story and I am stayin with it.

[falconblack]

I forgot to mention the reason the real big welders don't have power factor correction is that it is only beneficial on single phase units!!It allows you to use less amperage which means less power used and less voltage drop on under sized wire and so on!!

[TxRedneck]

I agree falcon.. I went from a ac/dc tombstone to a bobus. I dont plan on upgrading..except for a sa200 or pipepro or pro 300 :D

[Sandy]

Hence you can never have a big enough machine.....lol that is why we all upgrade to bigger never smaller.

There's gotta be some cave man instinct thing going there.:) Always looking for something bigger to club so we can get a bigger club to do it with.

If we got extra power we will find a way to use it,right?Right or wrong that is my story and I am stayin with it.

Well I'm darn sure not going to let any slip through my shop without being used for something, even if I have to get a bigger machine.

[TxRedneck]

lmao you guys i swear...I will say this, I would LOVE an SA 200. But felt it was out of my price range for what it was going to do. Yes I would LOVE one..but again, the bobus catus does what I need it to do...most of the time :D Would be nice to have a pipe pro wiht that dual power mode for inplant or shop work. But Im fine for now :D

[awright]

There's a remarkably similar thread to this one going on right next door under the heading, "Lincoln TIG 355 input power question." I presume many of the participants in this thread have seen it, but I see no acknowledgement of it. So here's a clip of one of my own posts addressing the question of why install PFC.

(Beginning of clip)"A subtext of this thread is, "what's in it for me to correct power factor on my machine?" Well, part of the answer has to do with what could be called good citizenship. (That's not meant to be snide. I can't think of a more apt term at 2 am.)

By pure coincidence, the January '06 issue of the IEEE (Institute of Electrical and Electronic Engineers) magazine, "IEEE Spectrum", that arrived yesterday contained a long article on a very expensive power factor correction device using superconducting technology and exotic control electronics that is used at the utility level. I haven't read the whole article yet, but skimming it, one paragraph caught my attention:

"Reactive power (provided by the new device - awright) is what's required to counteract lagging currents and sagging voltage (on the grid due to customer's inductive loads - awright), and if it isn't supplied quickly or efficiently enough, networks crash or equipment suffers. Indeed, reactive-power-supply problems are among the chief culprits in an overall power-anomoly and -disturbance problem that costs the United States alone between US$119 billion and $188 billion a year in lost economic activity, according to a 2001 report by the Electric Power Research Institute, in Palo Alto, Calif. Such staggering losses add up to 1.2 percent to 1.9 percent a year of the country's gross domestic product, the report noted."

You can see why the electric utilities penalize industrial customers that put large reactive loads on the grid.

So, it's kind of like voting - your individual action is small, but is an important part of the big picture. The day may come soon when the use of power factor correction is mandatory on welders, as is now the case with some consumer electronics power supplies (which are individually an infinitesimal part of the overall problem, but cumulatively are becoming a major impact on the grid).

I don't know about saving gas, but if you are using an auxiliary generator to supply your line-operated welder, power factor correction may save your generator from damage. It doesn't like reactive loads any more than the utility does."(End of clip. How do you guys highlight those quoted sections?)

If you haven't checked out the other thread yet you might find it interesting.

awright

[smithboy]

Actually, I was aware of the thread, but I had not realized it had moved its focus to PFC. Thanks for the heads-up.

[smithboy]

Awright,
I went back a read through all of the thread. I now feel like I have a better grasp as to why it is a desirable feature on a welder. I have a few questions and comments to make and I was hoping you would add your thoughts to either confirm or correct my understanding.

1) If you are a home user who is just looking at the dollars and cents of it, facing no surcharge, is there any economic benefit for you, as an individual, in adding the fairly expensive feature?

If I understand what the thread said correctly, the benefits to the home user would probably never rise to the cost of the feature or if it did, it would take a considerable amount of time...given that no punitive pricing of power came into effect for home users in the meantime. Even for the industrial user, the costs of the feature might exceed the benefits unless the power company was considering slapping you with a different rate schedule. But, that cost/benefit is not something that would have to be just taken on faith. Someone, with some reasonable guesses about electricity consumption and the particular set of circumstances could calculate the benefits with some degree of accuracy. The costs are pretty easy...$X for each of Y units with PFC installed + the forgone interest on the $$$ spent (remember, you could have put the money in an alternative investment and earned as much as you would have saved with PFC...well, maybe you could have). I agree that there may be social benefits of PFC, but those are harder to get a handle on, so I ignore them for now...but, I am not discounting them.

2) I have never seen the "option" of PFC on an inverter, but I always see newer ones with a "power factor" listed. Is this because they are, by the nature of their design (full of capacitors and junk...little technical jargon there), power factor correcting already?

I guess I am still just trying to draw an analogy from a different process that will help my understanding of this process.

3) Is power factor correction just attempt to "smooth out" electricity demand by, keeping more power available on the grid instead of tied up idly in a plant or in a machine that is idling? The analogy that comes to mind is gasoline demand. During last year, when demand spiked for gasoline, folks filled up as many "buckets" they could with gas as prices started to skyrocket. Now, what might be the equivalent of PFC on cars??? Ignoring time costs, suppose we only let drivers buy enough gas to get to the next gas station, plus a little for inefficiencies and uncertainties. If nobody cheated, more fuel would remain in the hands of gasoline suppliers or in the supply chain, and less would be idle in the tanks of cars that are not really using the gas while sitting in parking lots or even in reserve driving down the road or, worse yet, in gas cans in the garage. Instead, everyone gets enough gas to get the job done and holds none or little fuel in idle reserves (which I think may be somewhat analogous to "reactive loads"???).

Jumping back to electricity, in the long term (or on large scale), it would seem that what PFC really affects is the necessary power generating capacity during peak loads. Smoothing out power consumption appears to be the main benefit to everybody collectively and to the power company...employing PFC would lower the overall cost of electricity by increasing the efficiency of power generation (no idle generators or generating facilities...everything running at close to capacity all the time). Just as an aside, running at capacity has its societal risks and costs also, which may need to be factored in (see gasoline shortage 2005 and rolling blackouts in CA). Excess capacity is in some situations known as insurance.

Is this sorta accurate....or am I waaaaaaay off base here and completely missing the point. Don't be shy, I can take it...By the way, I really appreciate the time and effort you have taken to explain this. I am just learning this electricity stuff even though I have welded for several years. I have to say, my interest in the subject grows with each question.

[Sandy]

Smithboy, that was a good run down on some of the more collateral issues with PFC. I liked it.

One thing you alluded to was lagging current, which is interesting. Of the several, it is definitely one reason why power factor correction might be and is needed in some special cases. Not cost. There are occassion where industrial and light commcercial or industrial and light res are blended together in an area of older and minimally sized power backbone. We could picture some large plant (sawmill??) where many times daily some HUGE something or other kicks on, draining power, tripping HVAC breakers, browning lights, bla bla bla. Maybe every morning at a certain time they turn on huge motors, at noon they shut them down at twelve, fire them up at one, stuff like that. Power factor correction is used in these cases to bring the load to the door and keep it there so there is power on demand. It helps to prevent effects on neighboring residents and small businesses.




Jumping back to electricity, in the long term (or on large scale), it would seem that what PFC really affects is the necessary power generating capacity during peak loads. Smoothing out power consumption appears to be the main benefit to everybody collectively and to the power company...employing PFC would lower the overall cost of electricity by increasing the efficiency of power generation (no idle generators or generating facilities...everything running at close to capacity all the time). Just as an aside, running at capacity has its societal risks and costs also, which may need to be factored in (see gasoline shortage 2005 and rolling blackouts in CA). Excess capacity is in some situations known as insurance.

I particular enjoy seeing you bring this to light. All tho it sounds quite polly anna and paints a pretty picture it ain't possible and ain't gonna happen and from an argumentative stand point don't make sense. I'll keep the argumentative part to a minimum :) ...

"No idle generators" means water through the penstocks (sp) 24/7 instead of peak hours, coal boilers burning 24/7, natural gas boilers burning 24/7, nuke rods cooking 24/7, on and on. Save power at the end point?? Maybe.... Conserve Water?? Conserve Fossil fuels?? Conserve precious rescources?? Nope.

Then there is the issue of Loacal Distribution's ability to deal with lines that are energized at a higher state than they already are. I could go on for an hour posting questions to be answered by those who are suggesting this "cure". Number one and as you mentioned, think eternal brown out, untill the consumer forked over enough money to upgrade an entire area wide facility.

jusss rambling.

Thanx for listening.

[smithboy]

Efficiency is a term that gets thrown around alot, but the term's meaning really differes a good bit depending on how and where it is applied. In general, it just means getting the most from what you have. In the case of power generation for public use, I really am not sure even the power providers or traders really know what it means, or, maybe I should say, there is no collective aggreement among them. Do they want max technical efficiency...economic efficiency...make the most money (that was the goal in CA) ...serve the largest market...minimize capital investment...provide the most power at the least environmental cost (not likely)...who knows?

I agree with ya, though, sandy. There are always "green" arguments that sound good, but even the best suggestions from conservationists have unforseen economic costs, but I try to give them the benefit of the doubt (I just keep John Lennon's song "imagine" in my head while I think). That is also very true for the fossil fuel lobby also, and they also get the benefit of the doubt (No song goes with this). I was really trying to avoid, in the previous post, saying that the real beneficiaries of PFC was the power company...which is probably the real answer, but honestly I'm not sure yet. However, if "right-sizing" for daily use is their goal, this means that they can squeeze down in size and make larger than normal profits by reducing the quantity supplied when demand is at its peak, and all the while blame the higher prices on supply and demand, economic forces that are "out of their control"...Hmmmm. They can also segment their market more and extract a much higher price at each level of segmentation. It's a long-term profit strategy for the entire energy industry.

In a regulated market, costs and prices often do not get mentioned in the same sentance...unless it's to argue for increased rates in front of a public service commission. In an unregulated monopoly market...most folks only talk about damand and elasticity, because as long as folks want it and you are the only supplier...consumers gotta pay. Excess capacity especially hurts unregulated power suppliers in two big ways. 1) it's money tied up in plant and equipment that could be used more effectively elsewhere (at least from their point of view), and 2) it removes the ability to constrict power supplied and increase prices. In a regulated market #2 is less important, because prices are fixed in the short run. This is the more cynical point of view, but...

This is what I was getting at in the last line of the quote in your post...idle capacity is good for the public at the times when it's needed, but it costs money to keep it and power providers have NO incentive to keep it. We kicked and screamed about too little refining capacity when gas prices spiked...CA residents were nearly bled dry during a heat wave because of faked under-capacity...we want cheap power and fuel, but we want it to be produced in as lean a manner as possible...the two arent very compatible. If we want capacity, we have to pay a higher average price for power/energy...if we want higher efficiency in the production, we have to expect occasional shortages to make us crazy. If we want conservation, we have to see higher prices.

I guess I was just taking the description of PFC in the posts (both above and in the other thread) as given, and working throught the logic, while leaving my cynical hat on the rack. It's off the rack now.:rolleyes:

[awright]

Well, I don't want to pose as a power system engineer here - lots of this stuff is a mystery to me, too. But here are my thoughts at this point.

Smithboy, I think your energy storage concepts are mixing different aspects of the PFC/energy demand issues, probably as a result of people talking about reactive power "sloshing back and forth," or being "borrowed from the grid." While those broad concepts may help grasp what is happening instantaneously on the line, it is an error to conceive of that "sloshing" as storing useful energy and then returning it to be beneficially used elsewhere. It is ALWAYS better not to borrow the energy from the grid in the form of a reactive load in the first place. The reactive current is really just creating havoc and control and stability problems on the grid and decreasing the efficiency of power transmission by (among other things I have no knowledge of) causing unnecessary (I^2)R losses, (that is, wasted heat) in the transmission equipment. While the out-of-phase component of the current drawn from the grid does no useful work, it is comprised of real electrons flowing, does cause real heating of the transmission equipment, and creates the need to oversize some of the equipment (like conductors and breakers). [(I^2)R is simply the power dissipated by current I flowing through resistance R, and R is never zero, no matter how big your conductors and connectors are.] Note that the waste caused by reactive currents affects the entire generation/transmission system, meaning that the amount of useful energy you can get out of the generators in the power plants is reduced by the demand for reactive currents on the grid.

Your interesting discussion of storage and timely use of energy is properly related to intentional energy storage facilities, not reactive currents. Intentional energy storage includes such items as battery and capacitor banks, flywheels, pumped storage (pumping water uphill at night and releasing it through turbines during the day, as in the Helms Pumped Storage facility in the Sierras of California), even hydrogen production and storage (an extremely inefficient process, unfortunately). These are the types of energy storage that your gasoline analogy would be applicable to. But note that even the best of these energy storage concepts have less than perfect efficiencies, and some of them are extremely inefficient, wasting a major portion of the stored energy as heat during the storing and retrieving processes.

There is no way of gilding the reactive load lilly. A Power Factor other than 1.0 is always undesirable. Just how undesirable and the economies of PFC is beyond my ability to analyze.

As you observe, the individual end user may never see PFC as a direct benefit he can enter into his checkbook and will, therefore, generally decline it as an option. But he (or rather, all of us) is paying for the inefficiencies caused by not having PFC in many invisible ways due to the added expense of running the grid, cleaning up the air, health costs, wars for oil, etc. etc. This is the reason that policy planners concerned with such issues will probably eventually mandate that equipment be manufactured with PFC built in, maybe even making it illegal to remove or modify it (like catalytic converters on your car). Then end users complain about "interference by do-gooders and the government increasing the cost of his equipment purchases."

Sandy says, " Save power at the end point?? Maybe.... Conserve Water?? Conserve Fossil fuels?? Conserve precious rescources?? Nope." Well, Sandy, There's no more gentle way to say it - - - you are wrong on each of those points. Energy wasted in the losses THROUGHOUT THE GRID due to reactive current flowing must be generated by flowing water, burning oil, gas, or coal, or splitting atoms. See the quote in my earlier post here from IEEE Spectrum magazine (that you can buy off the rack in a well-stocked magazine strore) about the vast magnitude of those losses nationwide and their impact on the economy. Those are real dollars, and the Electric Power Research Institute is not a head-in-the-clouds, environmental think tank. It is the major research institute of the electrical utility industry, more given to fending off environmentalists demands on the industry than aiding them.

Then Sandy said,

"Then there is the issue of Local Distribution's ability to deal with lines that are energized at a higher state than they already are. I could go on for an hour posting questions to be answered by those who are suggesting this "cure". Number one and as you mentioned, think eternal brown out, until the consumer forked over enough money to upgrade an entire area wide facility."

I don't mean to pick on Sandy, but he provides a good example of many of the arguments against "social benefit" measures such as PFC.

Sandy, consider the hundreds of millions of inductive loads on the grid in the country. Every imperfectly loaded motor or transformer on the grid adds an increment of reactive load and contributes to wasted energy throughout the grid. Sure, the utility will seek out and penalize the big industrial user with a reactive load because that gives them the biggest return. But (without benefit of knowledge), I'll bet that the cumulative reactive load of millions of individual users is much larger than the really big industrial users. (This is partially due to the economic benefit that the bean counters in industry see in PFC at their site.)

It is important to realize that utility scale power factor corrective equipment such as that described in the IEEE Spectrum article will help the utility deliver the power, protect his generators, and stabilize the grid, but THEY DO NOT AND CAN NOT DECREASE THE LOSSES DOWNSTREAM DUE TO REACTIVE LOADS! So we individual users can't (legitimately) say, "Why do I have to pay more for my equipment? Just let the utility do the correction at the plant." Ain't gonna work that way!

smithboy says, "2) I have never seen the "option" of PFC on an inverter, but I always see newer ones with a "power factor" listed. Is this because they are, by the nature of their design (full of capacitors and junk...little technical jargon there), power factor correcting already?"

Well, here again I am guessing. (Hopefully an "informed guess.") As we all know, one of the major benefits of inverter-type welders is the absence of the big, heavy, costly transformer that transforms high voltage at moderate current to low voltage at high current at the torch or stick AND isolates the electrode from the power line for safety. The inverter can do this because it rectifies the incoming, raw power and stores the energy on a capacitor bank without isolating it from the line. The inverter logic and power semiconductors take this non-line-isolated energy stored on the capacitor bank and chops it up into high frequency AC power that is applied to the primary of an "inverter transformer" that, due to the high frequency, can be much smaller and use less material than a line-frequency transformer handling the same amount of power. (Transformer size is inversely proportional to the frequency of the power they transform.) The isolation of the electrode from the line for safety occurs at this much smaller inverter transformer.

The result of all this is that there is no big hunk of iron and copper hanging on the line looking like an inductor. (There are, however, other types of problems, like drawing power only from the peaks of the power waveform during rectification instead of uniformly throughout the wave. This causes a power factor problem of a different nature than the phase shift caused by an inductive load, but it can be handled by sophisticated electronic control measures in the logic of the inverter - one reason the circuit board is as congested as it is.) The bottom line is that PFC can be and is is built in to the logic of an inverter - I don't know how.

Sorry to have used up so many bytes and put so many of you to sleep.

awright

[smithboy]

Hey...dont appologise. I got to the end and was hoping for more. Dang that limit. Again, I appreciate your info. Being wrong is something I have gotten used to. I have been working up to being right more often. I am also getting better at being "close to right."

I am an economist, so that definately slants my views on many topics (it is hard to compensate for your own prejudices). As far as conservation is concerned, I just see the incentives for individuals and for firms and shake my head. The big problem with conservation of any type is that it cost more RIGHT NOW than not conserving. Very few people really want to pay now for a benefit years down the road, sometimes even months or days down the road. Furthermore, very few folks are willing to sacrifice thier own well being for the good of society on a continual basis...there are obvious exceptions, but they are exceptions.

This is about the point where folks I know start talking about not mixing religion and business, but, generally, that's becasue there is a conflict between money and morals. How do you make people care about this stuff if it is not in their immediate interest? Well, you have to educate, advocate and participate. I think you have done all of these here. At the very least, you have convinced me to take the time to become better acquainted with the issues. I often learn the most by being totally wrong and mostly ignorant at the outset.

Now...I have more questions...of a more...well...technical and hypothetical nature.

If PFC is as important and necessary as you claim, would it be possible to have it, instead of in every appliance or welder, somewhere more centrally located, like in the breaker panel or even further up the electricity stream? Why might it have to be in every appliance separately? The reason I ask is that it would seem much cheaper and maybe easier to require a $500 box be built into a $200,000 house, than to add 5% to every appliance that we buy. Furthermore, it would take care of older non-PFC stuff that we want to keep out of land fills (another conservation issue). I guess I am thinking since this is a modular add-on in a welder...well, maybe it could be modular and potentially flexible in other ways.

If this is not feasable, what would you suggest is the best way to incorporate PFC into wider use?

Finally, are the green energy-star stickers on computer monitors and printers part what you were talking about...is this an example of PFC in use in other areas of life? Or, is this just a sticker on stuff that turns itself off when not in use?

[Sandy]

I don't mean to pick on Sandy, but he provides a good example of many of the arguments against "social benefit" measures such as PFC.

Hey, no sweat. I can handle. Doesn't bother me at all. :)








Not a lot anyway.










My mom used to pick on me when I was a kid, but I got over that. Yeh, took awhile but I did.















I thought. HMMMM, That little twitch is comeing back.










Dang, maybe if I go back to the meds....







I'm okay really. :waving:

[awright]

Hang in there, Sandy. My niece is a therapist. I can refer you to her if things get out of hand.

[awright]

Wow! An economist-welder. There's an interesting combination.

smithboy, I think things are running away from me. I am an acoustical (noise and vibration) engineer who likes to melt and cut metal and play with electrons, not a power engineer.

But, since this rolling ball is picking up momentum, I'll try to ride it.

As I said, I do not think that power factor correction equipment can negate losses downstream due to reactive loads, although it can, ideally, minimize (I^2)R losses and the stress on generating and transmission equipment UPSTREAM of the PFC equipment. This is because your welder sees VOLTAGE on the line and draws whatever current is demanded by its functioning, i.e., its reactive load and the real power it is putting into its task. PFC equipment somewhere upstream of your welder can be sure that the grid can supply the reactive current your welder may be demanding without disturbance to the grid or droop in line voltage, but it cannot modify the reactive current demanded by your downstream equipment. Thus, the PFC equipment isolates the grid from your problem, but you are still wasting energy due to the reactive current demanded by your equipment.

The problem with trying to apply PFC to the whole house instead of the specific welder or motor is that if the PFC is not "smart," that is, if it is just capacitors permanently hung across the line, it can only correct for a specific amount of inductance on the line. Switch off your welder and the capacitors are still hanging there, drawing capacitive reactive (leading)current. That may, in fact, help the overall condition on the line due to all your neighbors' motors and welders (we all have neighbors who have welders at home, right?), but you are still drawing reactive current in your house and have to oversize your breakers and wires to handle it. Only now it is capacitive reactance, rather than inductive reactance. PFC correction at the load can work better because it is "tuned" to some known, average operating condition of the equipment by the equipment designer. A "smart" PFC would instantaneously sense conditions on the line and continuously correct for them. That's what the utility-scale PFCs would do and that's why they would cost many millions of dollars.

There is also some confusion between "efficiency" and "power factor." Efficiency is defined as the percentage of the energy going into a device that comes out as useful work. Because a poor power factor causes losses, it contributes to a decrease in efficiency. However, there are other factors unrelated to power factor that cause decreases in efficiency. Resistance in the wiring causes (I^2)R losses no matter what the phase relationship of the current to the voltage is. Anything that has to use a fan to keep the equipment from overheating is throwing away waste energy that is decreasing the efficiency of the equipment. The only difference is that (I^2)R losses due to the useful component of the current flowing through the residual resistance of the circuit is generally unavoidable, whereas the (I^2)R losses due to the reactive component of the current is avoidable (by applying PFC).

smithboy also says, " If PFC is as important and necessary as you claim, ..." That makes me sound like a PFC advocate. I'm not trying to get people to apply PFC in this discussion. I'm just showing off the little bit of electrical info that I think I remember from college in 1960 and picked up reading magazines. I don't have any PFC in my WWII USAF (Army Air Corps?) surplus Harnishfager 300 amp AC stick welder, and I'm not sure that I would try to install it, even if I could figure out how to do it. But I do think we all benefit from knowing what PFC is and does and what the issues are and make our decisions on good information, rather than myth.

Well, OK. Maybe I am trying to encourage OTHER people to invest in PFC.

awright

[falconblack]

I believe if we all do our part to conserve energy we will all be better off ofr it.In my business here in Canada(HVAC)we have been selling 13 seer units as a low end unit ie:heatpumps and air conditioners.If our clients change to these units the local power company pays the cost of the unit and installation and the customer pays them back in monthly payments.The loan cost is 4.9% over ten years which is about half off the savings in power to the customer.The reason is more people can be added to the existing power grid so the utility makes more money and does not have to enlarge the grid.The customer also gets rewarded by paying less for the same comfort.

[smithboy]

awright,
I didn't mean to turn you into a school teacher...but, I am affraid I did. If all new members were forced to cough up so much info in their first few posts as you have, I bet we would have a lot fewer members. You have given me a lot of ideas here and now I will have to sift through them to figure out how to think about this PFC thing. I thought it was pretty simple, just poorly explained. Now I know, it isn't that simple and it involves many parties and the benefits of it are not directed at a single individual. Manuals are not the best place to explain something of that nature.

Furthermore, I now understand that I don't know a lot more about electricity today...but, that's ok. This is the kind of stuff I like to understand, and you have, at the very least, moved me a bit closer and increased my desire to figure it out. Now it's book-buying time.

Now, while I am preoccupied, maybe you can get some free time to browse through the website and look at welding projects, without haveing to answer some of my relentless questions.:)

Much appreciated.

[awright]

smithboy, I don't feel oppressed by the questions. I'm having fun with this thread. I just want to make it clear that I am not the authority on the topic that I pretend to be. I'm really stretching my knowledge here.

falconblack, up to this point this discussion has been focussed on PFC correction in transformer welders by addition of kits offered by the welder manufacturers - presumably capacitors. Are your "seer" units applicable to welding equipment? What are they? How much current can they handle? Can you give us a little education on what your units do to conserve energy?

I'm guessing that they are based on the technology developed by NASA(?) back a couple of decades ago and incorporated into products and into external boxes you could put between the wall plug and your appliance to decrease energy consumption of motors running at less than full load. Is that correct? I think they sensed the load on a motor (probably by sensing current demand and/or phase) and if the motor was not fully loaded, would reduce voltage to that just required to keep the motor and equipment running. Then, they would apply full voltage when the motor was loaded. Does that make any sense?

I bought one of those boxes for my refrigerator ("Green Plug" or some such name) but it failed after a few months and I never replaced it.

Can you fill us in to what your device does, what savings are realized, and a link to product data? Is the operating principle of your "seer" units applicable to transformer-type welders? Am I correct in my understanding that it is the unloaded, idling welder that is the main power factor problem, or is the "coil" in the electrode lead also a significant part of the power factor problem while the arc is running? I suppose the phase shift in arc current imposed by the coil in the electrode lead must be reflected back to the grid via the power trandformer, but is it a significant reactive load? I guess it must be, since a high current is being phase shifted to smooth the arc.

I'd guess that, since a welder is doing nothing while idle (not considering powering any control electronics and cooling fan) a good PFC measure, at least for a stick welder, would be to have a fast action solid-state switch apply power to the primary of the transformer at the instant of scratch start of the arc. In fact, isn't that what TIG welders do with the foot control? I'm not sure a electromagnetic contactor is fast enough to do that job during a scratch start without perceptable lag that would disturb the operator. Or, is that what is already done in equipment that I can't afford?

There are probably some complexities involved in getting a good start to the arc that would require that some circuits of the welder be kept alive while the main transformer was off, and that may make retrofitting by the user a little difficult. I'm thinking of the saturable reactors controlling the current in my Harnishfager. And I think that complexity, along with the cost of a high-current, solid-state, bidirectional (AC) switch, is what will keep that type of PFC out of welders if they are not mandatory.

You still ok, Sandy? Sandy?

awright

[falconblack]

My units are heatpumps and air conditioners the analogy between the 2 are anything that will lower power demand is good for all of us,not just the power companies.That is what power factor correction actually does and so do higher seer rated units in the hvac business.The next step is DC.The key is the electronic boards....hence the increased cost to the consumer.

[awright]

I'm still in the dark about what a "seer" unit is and what it's operating principle is.

[falconblack]

Seer is just short for "seasonal energy efficiency rating" the higher the seer rating the more efficient the equipment is to run.Your fridge if it is more than 6 years old will be a power hog versus the new higher seer models.Same goes for your dryer washer air conditioner etc..There are insentives here from the power companies to upgrade to more efficient appliances of all sorts.

[awright]

Ah-Hah, falconblack. Thanks for the education. Is the seer rating a Canadian thing, or is it used in the U.S., also? I guess it has been quite a while since I bought a rated appliance.

The statement you made a while back, "In my business here in Canada(HVAC)we have been selling 13 seer units as a low end unit...," is what triggered my curiosity about those seer thingys were. Now that I know that it is a rating, not a thing, what does the "13" mean? Is that a good or a bad rating? What is the range of rating one will find on the street? Is it easy for you to describe to us how the seer rating is derived?

Thanks.

awright

[falconblack]

The seer rating is also in the US and 13 seer is the lowest rating you should get the highest being 16.Seer is derived from a more energy efficient compressor and motors.The compressors are usually scroll on the better units because they are designed to use less energy to accomplish the same job.The refrigerant used is usually puron instead of R22.Puron known to most people is R134a.More and more furnaces are also coming with DC drive motors as well which increases the seer rating of the entire system.