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#1 GGOSS

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Posted 18 July 2002 - 04:34 AM

Although I know a little about Power Factor Correction (PFC), I can harldy refer to myself as being an expert in this field.

I think for many forum members and for that matter forum visitors, an explanation of PFC terminology could form the basis for further learning of this interesting subject.

Therefore by way of this post, I would like to invite people more knowledgable about PFC than I to respond by posting information that will assist myself and others to become more familiar with PFC technology.

Suggested topics:

1. Glossary of PFC terminology.
2. Reason for installing PFC equipment.
3. The benefits of installing PCF equipment.
4. How to determine PFC requirements.
5. PFC installation precautions.
6. Traps for young players.

Do we have any volunteers willing to contribute?

Regards,
GGOSS

#2 marke

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Posted 18 July 2002 - 05:23 AM

Hello GGOSS

What a good idea. There are many misconceptions on this topic, what it means, what can and can't be saved. A number of Get Rich Quick schemes guaranteeing that the KWHr meter will spin slower etc.

Perhaps as a starting point, I can refer you to a paper on PFC and we can build on that.
Have a look at : Power Factor Correction

Regards,

#3 kim

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Posted 10 October 2002 - 04:32 PM

Hai GGoSS,

Forget about power factor, if you want to know better, log on to www.savawatt.com.
You need to prove energy saving on site, you cannot read reports or theories, they normally has no real value. Ask the investment return and warranty.

#4 marke

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Posted 12 October 2002 - 04:52 AM

Hello Kim

The technology you are refering to is that of an energy saver as opposed to power factor correction. The energy saver is covered in a different part of this forum, but was originally developed by Frank Nola at NASA and operates by reducing the voltage applied to the motor when operating inefficiently. Power factor correction does not reduce the energy used by the motor, but does reduce the energy wasted in the supply and is achieved by adding parrallel capacitors to neutralise the inductive current.
Have a look at http://www.lmphotonics.com/pwrfact.htm and http://www.lmphotonics.com/energy.htm
Best regards,

#5 grobert

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Posted 24 October 2003 - 03:29 AM

Here are the basics:
KW (kilo watt)= true power
KVA (kilo volt amp)= apparent power
PF (power factor ) = , your systems ineffieciency
KVAR (kilo volt amps reactive)
UNITY PF= kw same value as KVA
PF= KW/KVA
KW= KVA x PF
KVA = KW/PF

Use pathagarum therum to figure existing KVAR and needed KVAR to achieve desired PF.

KVAR = sq.rt of KVA (SQ) - KW (SQ)
KW = sq.rt of KVA (SQ) - KVAR (SQ)
KVA= sq.rt of KVAR (SQ) + KW (SQ)

These are the basic of PF corrections. You can have a leading (capacitive) or lagging (inductive) power factor. Remember that existing capacitor KVAR are entered as negative KVAR.

Your system only used KW but you paid for KVA. Capacitors will help to lower the KVA and your bill. PF is a by-product of inductive loads (motors, HID lights , non-linear loads). Homes consist of primarily resistive loads. It is not likely that you could save much with PFC.

Power company Meters measure watts not amps but watts are equal to I (sq) X R. If you can lower I (amps) or R (resistance) you will lower watts.

Inductive motors ( the primary target of PFC ) are a set HP and watt. You will not change that. As stated above you will pay for watts and there are 746 watts in 1 horsepower. You will save by lowering what your system uses above that actual required KW of the load

I am sure others will add to this. Hope it helps.

#6 Guest__*

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Posted 23 December 2004 - 04:08 AM

"It is not likely that you could save much with PFC."

I couldn't disagree more. Unfortunately, PFC is largely overlooked in residential applications, ... but not for reasons such as you mention.

From a marketing perspective, it's a weak sell in comparison to marketing to the poor folks that pay a PF penalty through their utlity rate structure (and there are many throughout the U.S.).
The benefits to these folks overshadow that which would be gained for the average homeowner.

In addition, residential PFC has been widely suppressed by utility companies for obvious reason that the savings on a mass scale would result in a substanial loss of revenue (I know from my own experience as an electrical engineer in a major utility company).

Residential PFC is also overlooked because of the huge skepticism amongst overnight internet "experts" who refer to the same old reasoning, namely that it can't save if your meter only reads kWh or homes are primarily resistive loads (what about the major loads!) or that they're "Get Rich Quick schemes".

I mention this because, unlike so many others who frequent these forums, I "put our money where my mouth is", along with two of my neighbors and purchased one of these residential PFC units. We've had consistent savings averaging in the upper teens (for the sake of not spamming, I won't mention the manufacturer) .

So where does the kWh savings come from? Primarily I2R losses. This raises the question, how high are I2R losses in the average home. You would think it to be relatively low. I have not found any studies estimating these losses and I would not begin to try estimating wire lengths, heat loss capacities, various fittings, couplings etc. Though individual component losses may be minute, they have to add up to something. Given all the appliances and convoluted gadgets in my home, the savings doesn't seem unreasonable.

That's my best guess. For those of you suggesting that the savings may have been due to a change of habit or whatever, that doesn't explain why all three of us averaged savings in the teens. Rather than trying to second guess my results, I suggest you get your own.

Finally, I've noticed recently that a number of these devices are showing up on the web by a variety of manufacturers. They range in price from $400 to $1,200 for whole house units (I' m familiar with the technology and $1,200 is a highly unreasonable mark-up). As I read more and more on the subject (sifting through all the internet motor "expert" hype) I realize that their popularity and success of these devices is not due to "uniformed customers and unscrupulous sellers". (In fact, I made it a point to became informed before purchasing and I imagine most purchasers have done the same.) Rather, I think their popularity is due to the rising cost of energy in the U.S. and homeowner's increasing willingness to lower their burden. I find it highly unlikely that so many maufacturers would produce this technology at great expense if they were meant to deceive. Based upon my experience, I say give them the benefit of the doubt until you can prove otherwise.

physguy3







The fact

#7 RalphChristie

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Posted 23 December 2004 - 07:41 PM

Physguy3:

Interesting comments.

I assume you are talking about a single phase supply (residential applications) Do you use PFC (capacitors) or is it a type of energy saving (reducing voltage - power factor compensation) device? I assume you are in fact talking about an energy saving device.

I know of no utility that charges a power factor penalty for residential service. I would be really very surprised if there was a metered demand component that differentiated between kW and kVA.

You are saying your savings are in the upper teens. Over what period? Can you provide the figures? I do agree you can have some savings, but what is the savings in comparison with the initial cost of the device? To quote Mark: Only energy that is being wasted, can be saved.

Just for interest sake, have a look at:
http://www.eng-tips....d.cfm?qid=86174

Regards
Ralph

#8 physguy3

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Posted 24 December 2004 - 03:38 AM

Hey Ralph,

Yes, I was talking about single phase residential applications. The device is being promoted as an energy saver. It also surge protects the entire home, which is a nice feature. It is not one of the TVSS energy savings scams however, (I checked into that before purchasing).

Two of my neighbors bought them at a home show for $550 back in March, 2004. While watching one of them install the unit, I agreed to look into buying one so that we could compare energy bills. (I found the exact same unit on the web for $400! Ha!). The savings on average were 17.2%, 13.4% and 16.52% respectively (with mine being the last) over the past 8 months. My house is 2800 sq. ft. and I was averaging $270 in energy costs. Given the price of the unit, and it's supposedly 25 year lifetime, it'll pay for itself many times over.

Regarding utilitiies that charge a power factor penalty for residential service, I remembered seeing on the web a few "power factor" rate charges for residences while reading up on the energy device I purchased. As I attempted to look back, I see now that ther were "power fuel factor" or "power cost adjustment factor" charges. Guess I was mistaken and I certainly know of no residential demand meters in use.

I read the forum at the link you provided at . Again, too many overnight "experts" and no one addresses I2R losses, only motors. Also notice that no one has taken the time to purchase and investigate. I'd like to hear from some who have. (I tire of people repeating something they've read on the web elsewhere. Okay, we all know that power factor correction reduces power supplied to the motor but not the power required of the motor. This point has been beaten to death on the web. Seems like someone mentions a product and everybody jumps on the band wagon to dispute the integrity of the manufacturer, even calling them cons" without investigating. Have you noticed this also?)

Finally, ... and not to be a wise ass, but I thought I'd take a stab at Mark's quote" only energy that is being wasted, can be saved". Seems like those devices that actually shave voltage (not the one I bought) do save energy that otherwise was not being wasted. Unfortunately, they are a dertriment to the longevity of the motor. Not that it really matters, but wouldn't you agree with this reasoning?

physguy3

#9 marke

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Posted 24 December 2004 - 05:12 AM

Hello physguy3

Welcome to the forum.
I would like to know more about this device before commenting on it. Can you provide a link to information so that we can investigate, learn and comment?
There are many devices out there that get presented as the way to save energy, but most of them will only work under certain conditions, and these are not the norm.
If you can reduce I2R losses, then you will save energy. This is what power factor correction can do, but the I2R losses reduced are all upstream of the correction. If you apply power factor correction at the main switchboard, you will not mearsure any I2R loss reduction as it will all be in the supply.
Power factor correction will only work where there is considerable inductive reactive current flowing. If the load is resistive, as it is in many domestic situations, there will be no I2R reduction, infact there can be an increase in current. - The power factor correction current is capacitive and neutralises most of the inductive current in the load. If more capacitive current is connected than there is inductive current flowing, (over correction) the net current will increase.

The statement that I often make "that you can only save energy that is being wasted" is a fact of physics. You can reduce the energy consumption of a lightbulb by reducing the voltage, but you also reduce the light output. You are reducing energy that is being used, not wasted. You are not increasing the efficiency of the system, just reducing the work done. If you try to do the same with a motor, as the voltage is reduced, the current can go up depending on the load on the motor shaft.

While there are some 'overnight internet "experts"' out there, there are also some very knowledgable people on the web, including this forum. Some of the experts who comment here, are proffessionals of international repute and well worth listening to. It is very easy to discount qualified advice as garbage when you do not agree, but sometimes there is a lot of substance and experience behind the statements and comments that are disputed.

I for one, would like to see a good factual description of the operation of the device you refer to with the theory behind it's operation. Can you oblige?

Best regards,

#10 Guest__*

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Posted 01 January 2005 - 08:31 AM

I purchased a unit like the one described for ~$600.00 at a home show in Michigan last July. I swear it saved me 12% - 14%. I'm no expert on electricity, but I do know that the savings is real, not imaginary. I would not have bothered to comment in this forum except that I agree with "physguy" that out of fairness, you shouldn't criticize a product without first giving it a try. I also agree that by naming a product in a forum, you can do irreputable harm to the manufacturer because forums are often used to do just that. Finally, I agree that it's very hard to believe that so many reputable manufacturers would take the time and expense to create a product that's meant to deceive the average homeowner. It's nice to hear from someone whose willing to offer their own assessment of these devices from actual experience.

melmel

#11 marke

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Posted 01 January 2005 - 08:52 AM

Hello melmel

Thank you for your comments, however I do not believe that this product has been criticized on this forum. Perhaps I am wrong and you can show me where.
I have certainly disputed some claims made by some of the promoters of the NASA energy saving system for induction motors, but I am qualified to comment in that regard. I held one of the first patents on the three phase implementations of the technology and the claims I refer to would have the motors running at greater than 100% efficiency and that just plain isn't possible.

If you refer to my earlier post, I have asked for more information, not offered a critical comment.
If you are not prepared to disclose the technology, then we can not agree with you, neither can we disagree, but with no disclosure and past experience, I expect most skilled technicians/engineers would be very wary of your claims.
Disclose more information and we can have a meaningful discussion. Make irrefutably false claims and you can expect negative comments.
We have seen power factor correction promoted as a means to save energy in a domestic installation, and that is not going to happen unless there is a very long distance between the point where the meter is connected and a very inductive load, and the correction would need to be connected at the load, not the meter board. Domestic installations are generally charged on KWHrs only. I do not know of any domestic installations with a KVAR tarrif. If there was a KVAR tarrif, then power factor correction may achieve something in a very small percentage of installations.
Best regards,

#12 Guest__*

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Posted 02 January 2005 - 02:19 PM

I just wanted to comment that the product saved me money, that's all. I was responding to the other guy who commented earlier about his success. I have no reason to make "irrefutably false claims" and I'm offended by the suggestion. I'm soooo certain you must be right and all these reputable manufacturers are outright liars. Sure! Maybe I'll comment again when someone else is willing to share their stories, but I don't see that happening on this forum.

#13 RalphChristie

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Posted 02 January 2005 - 06:49 PM

Nobody (Mark included) gave any critical comments regarding the energy saving devices or offended you - but how can you expect that anyone must believe it if you can't show any facts, or disclose any technology? If the product is really that good, why are you afraid to mention the brand?

Just because there are some internet adds that say you have to send $100 to this address and you'll become a millionare before the end of the year (and Mr B from L and Mrs J from K swear it worked for them) doesn't mean you are going to become a millionare. Are you going to send the money straight away? I do not believe so.

Lastly, here are a lot of guys (and Mark is one of the best) who know what they are talking about and it is well worth to listen to their comments.

Regards

#14 Guest__*

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Posted 04 January 2005 - 12:01 PM

"If the product is really that good, why are you afraid to mention the brand?"

Are you serious? I'm not afraid to mention the brand, I just fear for the poor souls that'll be victimized by your precious "opinions", which, judging by the lackluster participation in this forum, appear to be overrated.

"Just because there are some internet adds ... ."
Now you're calling me either gullible or worse, and that is offensive.

Listen guys, I don't have the technical knowledge to argue the inner workings of these things. I purchased one, ... it works and I thought I was sharing my experience with other end users. I apologize that I was misled into thinking that's what this forum was about. This is my last post ... and you can have the last word. I don't really care.

melmel

#15 physguy3

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Posted 07 January 2005 - 04:32 AM

Wow, I didn't mean to cause such a stir!

Sorry I had not responded recently, but I wanted to wait until I heard back from the product manufacturer's customer rep. as well as the local distributor.

As you might have guessed, they both were adamant about not particpating in an open forum about their product. They said that most "experts'" assume that the technology is based upon rudimentary electronics, and since they cannot divulge proprietary information, it would be fruitless to get into an open discussion. They stated that open forum sites rank at or very near the top of search engines such as Google and Yahoo. Hence any adverse comments about a product are immediately viewable and irretrievable. They worry that forums are notorious for not given manufacturer's a fair shake (something about favoring the little guy over "big" companies).

Out of fairness, however, I will divulge the name of the product if you email me at physguy3@yahoo.com. (You might consider giving the product a try before posting your opinions, though). No need to get back to me, because I'm happy with what I have, regardless of the "inner workings".

Regarding Marke's comments "that you can only save energy that is being wasted", I agree with you conceptually, it's just the wording that 's a bit fuzzy. I don't believe there is a physics law that says this. Perhaps if you were to rephrase the statement as "you can only save energy that performs work" it would be more consistent with thermodynamic principles.

Finally, I appreciate you addressing the I2R issue for me. What you've said makes sense, though still doesn't explain why the product works rather consistently.

phys3guy

#16 jraef

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Posted 11 January 2005 - 07:21 PM

GGOSS,
I have found this website ofers a decent explanation of the issues, although not necessarilly in the format you were looking for. http://www.kvarnrg.c...ptimization.htm
Ironically, they sell a product that implies energy savings, however if you read the information they provide, it clearly states that it saves on the energy BILL, but not the kWh, which may be a true statement IF your utility has a pf charge Mine does not for instance).
"He's not dead, he's just pinin' for the fjords!"




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