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CFLs and Power Factor - do you pay for it?

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  • CFLs and Power Factor - do you pay for it?

    I have a love/hate relationship with CFL bulbs. While they do save energy, the spectrum of many of them suck. The prices are way too high for a cheap import, almost $4 for soft white and almost $5 for daylight, in 2 packs (100W). Then there's the slow (unbearable in cold climates) turn-on times.

    Top that off with a very high failure rate for every bulb I've bought in the last 2 years (100% failure rate for several Sylvania 3 packs) and the fact that incandescents will be illegal some time after 2012 ... now in the UK and good ole California. JTiers posted some lovely photos a while back of burned out bases and there are other stories of tubes that have blown out, etc. spewing their mercury mist across your living or work space

    My curiosity got the best of me regarding their actual consumed wattage so I tested several. Voltage delivered to the bulb was 118v rms, current and watts as shown. Both are the Home Depot n'vision brand.

    60 Watt bulb - labeled 13W, measured 0.195 amps (rms), wattage = 23W

    100 Watt bulb - labeled 24W, measured 0.389 amps, wattage = 46W !!

    WTF? Wondering about power factor in these but never having read up on it, I did so and found that it is around 0.55, pretty close to the measurements.

    So, my question is, does your utility charge you for the power factor via the newer meters that can track actual power?

    Den

  • #2
    If they aren't already doing it they will soon. It's in the plan. If you don't see an adjustment for power factor it's unlikely that they are charging it. I'm pretty sure they will have to break it out like the natural gas energy factor.
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    • #3
      They will absolutely have to break it out, because it will be different for everyone..... they will not be able to apply a generalized adder to everyone (at least not without PSC approval).

      But first they have to get it onto the "tariffs", the Public Service Commission has to approve it, and set a rate for it, and all sorts of gobbledegook. Naturally they will need meters that read it, instead of being set to ignore it.

      They can NOT just add it on at will, because the rates are set and subject to approval by the PSC. That is true of most any "regulated monopoly" such as the power company, although some types contract with municipalities, such as cablc companies, etc, and have rates set that way, or may have rates unregulated within a certain range, etc.

      BTW, your "power" readings should be characterized as "apparent power" or "VA" (volt-amperes). Only the actual wattage readings are "power".

      It would cost a little extra to make the bulbs actually "look like" a resistor, with a high PF, but it is perfectly "possible" to do that*. However, you might note that even per your figures, the VA reading gives a substantial reduction vs the incandescent light. The VA is about half the resistive draw of the incandescent, and the actual power is 25% or so.

      *At my prior employer, I designed a power supply for a 2500 watt audio amplifier which measured out at a power factor of 0.999. That is only milliamps of harmonic current in many amps of draw. It obviously can be done for CF bulbs, but may not be practical as long as the manufacturers and buyers are willing to practically commit murder for a half-cent price reduction.
      Last edited by J Tiers; 01-16-2009, 11:24 PM.
      1601

      Keep eye on ball.
      Hashim Khan

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      • #4
        Nheng,
        That is an interesting set of figures. A .55 power factor is nuts. I will have to make some measurements on this. I have a very good power factor meter, the only problem is that the current transformer is to large for the small current of a single cf bulb, I will have to get a low current ct for my meter or do it with a scope and a shunt.

        J
        Around here the local power companies charge industrial 3 phase customers for power factor already, single phase industrial and residential customers are not currently metered for power factor but all it would take is a meter change. Our power companies (public utility districts actually) don't add the power factor surcharge until the power factor drops below .95 for one county and .90 for the other. If the power factor drops below the threshold then the multiplier kicks in for the whole power factor and the total usage of the billing period. I have seen the power factor charge for a medium sized facility in excess of 30% of the bill. It is really frightening when I can sell a $100,000.00 automatic correction bank and have it pay for itself in less than 1 year . I hope that you are right about the tariff issue and that if the power factor issue with CF lighting is true that everyone takes a step back and re-evaluates the benefit of these lamps.

        Robin
        Robin

        Happily working on my second million Gave up on the first

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        • #5
          The PF at 0.55 seems low, but a lightly loaded rectifier/capacitor filter system DOES typically have a low PF.

          Anything that makes current draw look "not-like-a-sine-wave" is just as bad as a phase-shifted sine wave current draw, which is the classic definition of bad power factor.

          The effect of such a rectifier system is to delay current draw until the peak of the sine wave, at which point a substantial current pulse occurs.

          With a larger capacitor, the current pulse is quite large, and lasts only a short time. That will have a rotten power factor.

          With a smaller capacitor, it starts earlier, and lasts longer, improving the power factor. A heavy load has the same effect of PF improvement, as does an input inductor, found on many large VFDs (50Hp and above).

          The filter cap for a CFL is pretty small, the fried ones I have show 22uF. However, the other half of that is that the tube probably won't "fire" until it has a certain minimum voltage. The small capacitor won't "hold up" voltage very long as the sine wave is on the downslope.

          The effect of the tube is thus to delay current draw until later in the cycle, and probably cut it off at an equivalent voltage as the sine wave heads for zero. That would make it similar to a rectifier system with a large capacitor, and give a bad PF.

          A PF of 0.55 could be quite possible. The PF of a rectifier system can be lower than that, depending on values and conditions.

          I am aware that industrial customers are charged for many things that are not chargeable to the residential customer. PF, Max demand, lots of things which the dumb consumer is not charged for.

          And I was very amused to hear that the local Fox News outlet showed a guy who installs PF correction caps on houses....... report was complete with the dramatic reduction of current draw on an unloaded motor..... great demonstration..... too bad that the reality is that residential meters actually still have a correction feature to correct out the effect of power factor, and register only kilowatt hours. So people will not realize any savings from the devices.
          Last edited by J Tiers; 01-17-2009, 12:49 AM.
          1601

          Keep eye on ball.
          Hashim Khan

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          • #6
            Curious, lets try this out... I've got a consumer plug-through meter: http://www.thinkgeek.com/gadgets/travelpower/7657/

            Bulb is listed as 18 watt, 120V, 290ma, meter reads :
            120.9 V
            .33 amps
            29 watts
            44 VA
            .66 PF

            -Matt
            Last edited by Ryobiguy; 01-17-2009, 01:16 AM.

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            • #7
              Originally posted by Ryobiguy
              Curious, lets try this out... I've got a consumer plug-through meter: http://www.thinkgeek.com/gadgets/travelpower/7657/

              Bulb is listed as 18 watt, 120V, 290ma, meter reads :
              120.9 V
              .33 amps
              29 watts
              44 VA
              .66 PF

              -Matt
              Matt,

              I wouldn't put too much faith in that device. Using it's own figures:

              120.0 Volts X 0.33 Amps = 39.9 VA

              But it says 44 VA. A 10% error somewhere. Not very accurate. Cheap analog meters are rarely any worse than 5% accuracy spec. Cheap digital ones (this one is digital) are usually 1% or 2%, good ones are far better.

              But what do you expect from a place that calls itself "thinkgeek".
              Paul A.
              SE Texas

              Make it fit.
              You can't win and there IS a penalty for trying!

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              • #8
                Matt's post really tells it all... they are well aware of the power factor problem just not telling the public what it means. The ratings Matt provided say that the bulb is rated at 120 volts, .29 amps and 18 watts. Now if we do the math assuming a power factor of 1 then watts=volts X amps or 120 X .29 = 34.8 watts HMMMM not 18 watts as claimed. Now if we assume that the 18 watts claimed is real power and the 34.8 watts is the apparent power then: power factor = real / apparent or 18/34.8 = .517 and that sucks. If this is the case then you can bet that I will be hording tungsten filament incandescent bulbs and gladly paying the power bill for power that I really used

                I do see the problem for the utility companies and they will start billing as is appropriate. With a lousy power factor the metered power is not the actual power drawn from the power grid, so the billing is incorrect. Also, the utility has to build the grid to be able to supply the current needed and that cost money, with poor power factor the actual current appears to be less than it actually is and someone is going to pay for the upgrades to the grid .

                Robin

                PS: Not to gloat but the power in my county is the second cheapest in the country, I think .021/KWH so burning power is not a problem cost wise.
                Robin

                Happily working on my second million Gave up on the first

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                • #9
                  CFL bulbs are only the most visible part of the problem. The utility companies are faced with an explosion of devices that generate harmonic distortion of the sine wave because they don't come close to a power factor of 1. This does a lot more than cost them money in generating capacity. It makes it very difficult to maintain something that still looks like a sine wave. This has wide implications for the entire North American grid because of all the interconnections. You can't just switch on another part of the grid by throwing the great big knife switch or something. The systems must be synchronized very accurately at the point where the interconnect takes place.

                  Problems caused by electronic switching power supplies as loads make it far more difficult to match up various parts of the grid. It's bad enough that in order to tie large parts of the system power is converted to DC and then back to AC via very large and expensive convertors at the interties.
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                  • #10
                    Originally posted by rdfeil
                    Now if we do the math assuming a power factor of 1 then watts=volts X amps or 120 X .29 = 34.8 watts HMMMM not 18 watts as claimed. Now if we assume that the 18 watts claimed is real power and the 34.8 watts is the apparent power then: power factor = real / apparent or 18/34.8 = .517 and that sucks. If this is the case then you can bet that I will be hording tungsten filament incandescent bulbs and gladly paying the power bill for power that I really used
                    Then you LOSE, suckah.

                    If you notice, even with the poor PF, the equivalent apparent power for a 100W bulb is around twice as large as a 100W equivalent CF.

                    So usually, the net current draw for a CF is STILL LOWER, despite the PF issue.


                    I do see the problem for the utility companies and they will start billing as is appropriate. With a lousy power factor the metered power is not the actual power drawn from the power grid, so the billing is incorrect. Also, the utility has to build the grid to be able to supply the current needed and that cost money, with poor power factor the actual current appears to be less than it actually is and someone is going to pay for the upgrades to the grid.
                    The grid can be cheaply "upgraded" by improving the power factor.

                    That can be relatively cheaply done by adding PF correction capacitors at strategic places. The power companies, not being complete dorks, have been well aware of this for almost 100 years now......... and do that on a regular basis.

                    The effect of poor power factor on DISTRIBUTION is therefore minimal if correction is installed.

                    The main problems are twofold......

                    1) the billing issue, loads that mess up the PF are not penalized unless they are industrial. So a ton of poor PF in houses can only be addressed in the mass, by a distribution-level corrector.

                    2) In large apartment buildings, poor power factor and harmonic generation cause the current in the neutral to go up drastically. It can be larger than the current in any one phase wire, and require an upsized neutral.

                    In europe, where the grid seems to be more fragile than in the US, its a big issue, because in typical european material-minimizing fashion, the neutral may not be sized even as large as the phase wires, because they count on balance. In the US the neutral must be equal sized.
                    1601

                    Keep eye on ball.
                    Hashim Khan

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                    • #11
                      Screw CFLs

                      If incandescent bulbs are criminalized, then maybe I'll do some experimenting with beam spread and convert my whole house to bright LED lighting. It seems that all flashlight makers are pouncing on it the past couple years. The thing I'd look forward to is not having to change bulbs for several years. Seems like the couple CFLs I've used don't last long either. I'm sure that has been engineered into them. The lack of "warm-up time" is appealing too - that's something about fluorescents that drives me insaner every time.

                      Just can't buy anything decent anymore. Capitalism is making my project list longer all the time. A log cabin in the woods is looking better every day. I think that's where my retirement vector is heading. The normal path sure doesn't look acceptable.

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                      • #12
                        I'm already using LED lighting. My work light at this work station is a 3 watt 12 volt LED that is a drop in for a 20 watt halogen track light bulb. It is about the same brightness and has a perfectly even 90 degree beam spread. I also have a couple of lower power LED bulbs in other locations as 24/7 lighting that give sufficient visibility to navigate stairs etc. As the price comes down I'll be switching gradually to LED. They now have drop in replacements for fluorescent tubes that use about 8 watts and have the same output but they are still expensive. That is changing as the are now integrating multiple emitters on a single die. LED bulbs are now available with outputs up around 1000 lumens.
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                        • #13
                          I read somewhere that despite the energy savings at the end user's location CF bulbs actually were worse for the environment overall than a regular filament bulb because the manufacturing process used far more energy, they require more materials (diodes/transformers all have to be manufactured as well) and labor and of course the mercury issue.

                          If that is in fact true why is there such a huge push for CF bulbs?

                          I can't get an honest answer from anyone other than "OMG! CF BULBS MAKE YOUR BILL LOWER."
                          This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
                          Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numb
                          Plastic Operators Dot Com

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                          • #14
                            The true cost depends on longevity, obviously.

                            The glass etc in the incandescent is not cost-free, nor environmentally benign.

                            But if the CFL lasted 8 years, and used 1/4 the amount of energy, while on for 8 hours per day.......The cost of the incandescent, energy wise as to use, would be 292000 watt hours, vs 73000 watt hours for the CFL.

                            One watt hour is 3600 joules. Therefore, the usage of the incandescent would be one billion joules. The CFL would use a bit over 250 million joules. The difference, of 750 million joules, is probably enough to manufacture the CFL, although I have not split it out.

                            not only that, but you would probably use more than one incandescent.

                            Now, with some cheap CFLs, they last 6 months, much less than a regular bulb, but obviously have a larger impact environmentally. That is a loss, certainly, as it would take 16 CFLs to go 8 years.

                            I have had old CFLs last 12 years of useful life..... the old ballast type. They most likely saved their cost, in every way.
                            Last edited by J Tiers; 01-17-2009, 01:55 PM.
                            1601

                            Keep eye on ball.
                            Hashim Khan

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                            • #15
                              The answer is simple but tied up with other issues. CF bulbs do save energy in use. That is the main thing. This means fewer power plants and less greenhouse gasses and less global warming. At least that is the stated reasons. Other reasons exist. If a product costs twice as much and lasts twice as long and has the same percentage markup the manufacturer makes twice the profit up front instead of waiting until the half price product wears out and must be replaced. In big business that is a huge reason to push a product even if it looks like a wash in the long run. It isn't a wash though since that up front income can be invested and makes money.
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