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LED breakthroughs - Page 2

post #31 of 51

 Ah that makes sense now.  For a moment was like that's one big LED.  :)  I'm in Newcastle!  :)  Lakeside neighbors.  ;)  Wonder if there is a Seattle-Eastside Eco Meetup?  :D

post #32 of 51
Thread Starter 

We have this thread about some new bulbs from a manufacturer in China called Brilliance LED which is producing a bulb called EcoDim.  I don't think it's available through retail stores, but the cost does appear to be pretty low.

 

Bobkart, do you know where the Geobulbs are being manufactured?

post #33 of 51
Quote:
Originally Posted by stins:

We have this thread about some new bulbs from a manufacturer in China called Brilliance LED which is producing a bulb called EcoDim.  I don't think it's available through retail stores, but the cost does appear to be pretty low.

 

Bobkart, do you know where the Geobulbs are being manufactured?

 

I'll check that thread out soon . . . my impression is that the GeoBulb is *not* being manufactured in China, based on email exchanges with their Customer Support Representatives combined with all the talk about FCC and UL approvals as well as the testing at Luminaire Testing Labs in Allentown, PA.  No doubt this is a big part of the reason for the lengthy process of bringing this LED lamp to market and the high price.  I would have to guess that there are far fewer hoops to jump through in China, and that is probably also why the majority of those LED lamps are only available online, because to be able to sell them in stores, similar FCC & UL approvals must be obtained, with the obvious additional time and money that requires.

 

This might be a good time to caution people about installing products in their home that do not have UL approval.  UL and similar entities are there to help make sure products such as light bulbs are "safe" i.e. they won't electrocute you or burn down your house.  I have heard (remotely) of problems with insurance claims when the cause of a fire (for example) is traced to something that was not UL listed.  I can't really say for sure that this is a real problem or that someone only thought that was the case and passed it on as fact.  And I'm not keen on calling my insurance company and asking about it since there is the possibility of them being forwarned that I might be using "unsafe" products in my home.  My impression is that there is little danger of an LED lamp causing a fire, but there are different designs out there and some could have more risk than others.  I just don't leave any indoor lights on when nobody is home (or only very rarely).

 

 


Edited by bobkart - Thu, 15 Jan 2009 20:24:06 GMT
post #34 of 51
Quote:
Originally Posted by BioGreen:

LEDs are the most efficient when your power source is DC, ie. a battery, like on a car, truck, boat, or flashlight, but they are not competitive for efficiency when your power source is AC.   With an AC power source, fluorescents or CFLs are still more efficient.  It will take some major breakthroughs to change this.

 

The problem with this is that most people assume that it doesn't matter if your power source is DC or AC.  LEDs run on DC,  and the reason fluorescents are more efficient than LEDs for an AC power source is that they don't require power losses caused by converting AC to DC.  LEDs in the home for home lighting are a scam, unless you are using a battery sourced application, such as an emergency flashlight, or unless you are off the grid using wind / solar power to charge a big battery bank instead of using AC bought from the utility company / coop.

 

This is why LEDs aren't commonly found in homes, but fluorescents are, and why we see LEDs increasingly in use in boats, cars, and trucks.

 

post #35 of 51
Quote:
Originally Posted by BioGreen:

LEDs in the home for home lighting are a scam, ...

 

 

You are certainly welcome to your opinion.  I disagree.  Converting AC to DC is not that big of a deal.  I've seen efficiencies as high as 90%.  So what would be a 9-watt DC LED lamp becomes a 10-watt AC LED lamp, with the same light output.  Most every electronic appliance has this same conversion happening, including computers.  Of course it would be that 10-20% more efficient to have DC power running through your house, and some people have gone that extra step.  It's not that changing your light bulbs to AC LED lamps *won't* save energy, it's just that wiring your house with DC and changing your light bulbs to DC LED lamps will save even more energy (10-20%).  But wiring your house with DC is not an option for everyone (certainly not an inexpensive one), changing a light bulb is much more likely to be.  The cost/benefit equation matters to most people, if you are trying to save energy "at any cost" then wiring your house for DC and switching all your light bulbs to DC LED lamps is one good way.  Others will consider the rewiring cost too high and settle for saving most of the energy that you would save that way by just switching to AC LED lamps.  I've seen as much as 50% energy savings by switching from a 10-watt CFL to a 5-watt LED lamp.  It's a little less light but it's more directed, so depending on the application you can actually end up with more light where you need it.


Edited by bobkart - Sun, 18 Jan 2009 00:09:11 GMT
post #36 of 51

To add to your comments, Bobkart, if someone were to do such a conversion of their home (assuming it's not new construction), the retrofit of the wireing, construction costs and material (ie: wall repair), and additional materials like DC outlets and appliances - is very non-green as it would be an incredible amount of "consumption" when compared to simply changing out appropriate bulbs.  All of these items have an energy footprint incurred during manufacturing that would likely never be made up by such a conversion in a reasonable length of time...

post #37 of 51

Here's another breakthrough... a new technology to produce cheaper LED lights! They've found a way to grow gallium nitride (the stuff that produces the light) on silicon at room temperature. That means cheaper gallium nitride, which means cheaper LEDs.

 

Commercial production is still five years away, though.


Edited by dordal - Thu, 29 Jan 2009 17:09:34 GMT
post #38 of 51

I finally got ahold of one of those GeoBulbs from C Crane (about a month ago).  I recently put it in my home-made integrating sphere and got results placing it right around the same overall light output as a 40-watt incandescent light bulb (by comparing readings between the new bulb and a range of 40-watt bulbs).  That checks with their specifications of 446 lumens (that's the Cool White version) and a typical 40-watt bulb output in the range of the low 400's.  Unfortunately they are still claiming "60-watt equivalent" which is simply not the case.  The one thing it has going for it is a relatively diffuse and omnidirectional output compared to most LED lamps.  At 446 lumens and 7.5 watts (this my wattmeter was able to confirm), it's just average in luminous efficacy at just under 60 lumens per watt.  There is a slight humming sound coming from it when on, that can be heard from as much a 6-10 feet away, depending on how much other ambient sound is in the room with it.  The combination of high initial cost and somewhat-shorter-than-most lifetime (30,000 hours versus 50,000 hours) makes it not fare well in a cost-per-megalumen-hour calculation:

 

initial-dollars: 120
watts-consumed: 7.5
dollars-per-kwh: .1
thousand-hours: 30
average-lumens: 379.1
dollars-per-mlh = 12.5297

initial-dollars: 1
watts-consumed: 40
dollars-per-kwh: .1
thousand-hours: 1
average-lumens: 400
dollars-per-mlh = 12.5

 

Note that it just matches the 40-watt incandescent.  To be competitive with a similar output CFL (say a 9-watt model), the price would have to drop to just $14:

 

initial-dollars: 14
watts-consumed: 7.5
dollars-per-kwh: .1
thousand-hours: 30
average-lumens: 379.1
dollars-per-mlh = 3.20936

 

initial-dollars: 3
watts-consumed: 9
dollars-per-kwh: .1
thousand-hours: 10
average-lumens: 374
dollars-per-mlh = 3.20856

 

Of course such a comparison ignores less tangible differences between incandescent/CFL/LED lighting.  Still, there are far more cost-effective alternatives to the GeoBulb that are also LEDs, such as this one I also recently acquired, from eBay:

 

6-watt, 500-lumen A19-style LED Lamp from LEDBulb.Bizz on eBay

 

(although I did find the wattage to be closer to 7 watts than 6 watts).


Edited by bobkart - 5/18/2009 at 07:40 am GMT
post #39 of 51

Cool... I expect that things will change dramatically in the next 2-3 years. 

 

It's only been a short time since white LEDs were even possible.  I can remember when blue LEDs came out and were like $20 each.

 

I am one of those weirdos whose got a big bank of solar batteries in the living room and have wired up a couple of 12V LED lights in series to replace my AC light - albeit just in the room with the battery.  They are very dim (maybe only equivalent to a 5W incandescent each) but that's ideal for my movie theatre where I just wanted some ambient light.  Saved using the 3x 40W incandescent spots on the ceiling with a dimmer.

 

The rest of the house runs on CFLs that are powered through the existing wiring by an inverter.  It's way too much hassle to re-wire a house for DC and at 24V you'd need much bigger wiring than at 240V. 

 

AC is much easier and safer to switch at high power as DC is prone to arcing across the contacts.  AC is easier to switch because 100 or 120 times a second the current stops so any arc is short lived and extinguished automatically at the zero current cross-over points.  With high power DC, it just keeps burning until the contacts burn out or the house burns down!

post #40 of 51

If it is LED or flourescent I will not use them and I will advice others to not use them,; don't you have any consideration for people with vision problems and light sensitivity?

 

LED and flourescent is painful to the eyes of most people and the high pitch buzz of LED and flourescents is so annoying.

 

I hope the new ESL lights are not painful.

post #41 of 51

Most people do not find fluorescent light "painful".  Fluorescent lights have been in service in work places for decades.  Most people haven't seen a LED light used in any work place or at home yet as they are just being introduced now. So it is unlikely that most people would have even seen one let alone been "pained" by it.

 

Modern good quality CFLs do not make a "high pitch buzz" although they do hum a bit at 100 or 120Hz (the first audible harmonic of the 50 or 60Hz mains fundamental frequency which usually nobody hears).  Avoid the unbranded cheap far eastern CFLs as those have caused me trouble (not least they tend to have a shorter life).  I use mostly Phillips ones.

 

LEDs only flicker if they are driven badly with unregulated and unsmoothed DC current from AC.  As they cannot operate on AC directly they should use electronics to convert that AC 120/240V to 1.2V DC (or some multiple if the LEDs are strung in series inside the "bulb").  Operated from properly smoothed DC they will not flicker at all. 

 

I have seen bad LED design examples but only on cars where they used early LED tail lights that were dimmed by pulsing the DC to give a running light perceived brightness equivalent to 5W tungsten and then run at 100% duty cycle to give an equivalent 21W tungsten light for brake lights.  When pulsed at a low rate (maybe below 100Hz) they were very disturbing as when you moved your eyes while following such a car you could see the stroboscopic effect as moving red dots.  Later LED car lights strobe at a much higher frequency (>1kHz) that isn't visible.

 

Some people are sensitive to the narrow colour spectrum of old CFLs and early LEDs that only use two narrow wavelength phosphors to create the "sickly" blueish light.  Newer LEDs and fluorescents use broader spectrum tri-colour phosphors that much better approximate white light.  You can even buy "daylight simulation" fluorescents that can replace the old blue "daylight simulation" tungsten bulbs for art work where colour rendition is important.

 

The technology has been rapidly improving over the last 5 years and in the majority of cases it is a suitable replacement for tungsten lighting.  The one area where there is still some debate is in the difference of so called area lights versus point source lights that some people claim makes reading difficult under CFL (or any area light source).

 

Even in these cases the argument only stands up if the user had such a problem that they have to use un-frosted tungsten bulbs in direct light fittings (i.e. without diffusers or reflectors) to achieve something like a "point source" light with hard shadows.  Normal reading lights (anglepoise, etc.) usually have reflectors or diffusers or use frosted bulbs (even standard R40 reflector bulbs have frosted reflectors and / or front face glass) so there aren't many situations even with traditional lights where you would get a point source light effect.

 

Having said all that, I still use a halogen reading lamp for checking my colour prints as I don't have "daylight simulation" CFLs in my computer room.

post #42 of 51

Sharp is entering the LED market techon at http://techon.nikkeibp.co.jp/english/NEWS_EN/20090612/171652/

 

reports their offerings and approximate prices.

They say they are offering color adjustable models and models useable with a dimmer.

 

40W equivalent versions are stated to be 40 USD while 60W equivalent would be about 50 USD.

 

The quality should be there with Sharp and it is an indication of more competetion on the way! 

 

post #43 of 51

A better link for the Sharp LEDs follows:

http://www.sharp-world.com/corporate/news/090611_2.html 

post #44 of 51
Quote:

BioGreen said: "LEDs in the home for home lighting are a scam, ..."

 

bobkart said: "You are certainly welcome to your opinion.  I disagree.  Converting AC to DC is not that big of a deal..."

 

I can see both sides of this discussion. While it is true that there are a few LED bulb manufacturers that diligently make sure their AC-to-DC power conversion is efficient (on the order of 90% efficient, i.e. with "power factors" greater than 0.90), there are far more that DO NOT use efficient power-conversion circuitry (I have seen cheap LED bulbs with power factors as low as 0.30). In a nutshell, with regard to the products availaable today, you get what you pay for.

 

I totally disagree with BioGreen's statement that CFLs are completely efficient. CFLs are a definite improvement over incandescent bulbs for many general lighting situations, but they have their own dirty little secret that so far very few consumers know about. I personally have instrumented a number of CFL bulbs and found that the majority of them have power factors down in the 0.50-0.60 range, which means that if it is labeled as consuming 23 watts in your home and it has a power factor of only 0.50, it is actually consuming at least 46 watts of energy back at the power plant (ignoring line losses, which only make the picture worse). You don't even have to instrument a CFL bulb to figure this out, if the manufacturer has labeled the base of the bulb with both watts and amps. Just multiply the amps (typically around 0.250 A) by 120 VAC, and you'll know roughly how many watts your "efficient" (ha!) CFL actually burns back at the power plant.

 

I have found that most of the cheap LED bulbs have power factors as low as 0.30, whereas the high-end manufacturers (Cree, Progress Lighting, others) have power factors of 0.90 or better for their "LED light engines", and a few screw-base bulb manufacturers have power factors in the 0.80-0.90 range, but it is definitely not the majority of producers, so one has to watch out. Unfortunately, the only way I was able to determine this was to build my own "test stand" so that I can measure the actual volts and milliamps using a true-RMS meter for measuring electrical current, do the math myself, and compare those real-world measurements to the manufacturer's specifications. I also use the Kill-A-Watt® P4400 power meter, which is fairly accurate for watts, but so far has been highly inaccurate for amps and power factor (at least my individual Kill-A-Watt meter is innacurate for measuring the true RMS current of low-power LED bulbs and CFLs, and anything with a capacitive type of power conversion circuitry).

 

The consumer agencies (for example the California Energy Comission) are not looking out for us here, they are still allowing manufacturers to sell these poorly-designed CFLs and LEDs with lousy efficiencies. It is definitely a case of "let the buyer beware", and unfortunately with most LED bulb manufacturers, the consumer has to be sophisticated enough to get the info for themselves. I have heard (anecdotal, not verified fact) that the electric utilities in the state pushed for minimum power factors in all bulbs sold in CA, but the manufacturers pushed back so hard the energy commmission caved in on that one.

 

I personally will absolutely not buy any of the low-efficiency, cheap LED bulbs, and I will support only the responsible manufacturers that produce bulbs with clean, efficient AC-to-DC power conversion circuitry. It is NOT just "lumens per watt" we all need to consider when we talk about LED and CFL efficiency, its must include the total power consumed back at the power plant that should be part of the product-choosing process for all consumers.

 

At any rate, high-quality LED lighting is already competitive with CFLs in terms of fucntional desireability for home lighting, although the up-front cost for LED lighting is not yet competitive in most residential settings. But then, CFLs have had a couple of decades to mature and refine themselves and bring down cost (recall that in the 1980's a 20-watt CFL cost $20), and LEDs are currently in their infancy in terms of home lighting.

 

Each technology (incandescents, arc-lamps, tube fluorescents, CFLs, LEDs) has its place, and none of them are a panacea. There is nothing to gain for anyone in "choosing sides" and being dogmatic about any given technology. The smart person looks at each technology based on its own merits and applies whichever technology appropriate in a given situation.

post #45 of 51

Power Factor is not the same thing as efficiency.  If the VA ("apparent power") of a load is 120 VA, and the Power Factor is 0.5, 60 watts ("real power") are consumed by the load, 60 watts are measured by the power meter for billing purposes, and 60 watts are generated by the power plant (not counting line, transformer, etc. losses).  A load with a low Power Factor (say 0.1) is in no way somehow consuming more watts (10x in the case of a 0.1 PF) somewhere upstream of the load.  Power Factor is simply an indication of how much of the measured current is being drawn upon as the AC voltage varies through one cycle.  A simple-to-understand example would be a half-wave rectifier, which would only draw current on (say) the positive half of the AC cycle.  While it might draw 1 Amp during that half of the AC cycle, leading to a VA of 120VA (for 120V AC), the fact that it is only drawing current for 50% of the AC cycle yields a Power Factor of 0.5, and watts consumed of 60 watts (Watts = VA * PF).  Follow the wires back from that load to where the power is being generated and if you set aside line losses it will be the same 60 watts the whole way.  There is no sudden change to 120 watts anywhere.

 

en.wikipedia.org/wiki/Power_factor

 

The claim that better Power Factors imply less power consumed for the same "output" (in the case of this discussion the output is light) is one used by companies marketing Power Factor Correction devices (typically a bank of capacitors).  They claim that you can save money on your power bill by improving the overall Power Factor of your house (considered as one big load).  Typical inductive loads (electric motors) have less than unity Power Factors because they are drawing current "out of phase" with the peak voltage in the AC cycle.  Capacitors, by storing energy for a short period of time, can mitigate this "out of phase" situation by filling up during the peak voltage of the AC cycle then supplying that excess to the electric motor when the power line voltage has gone down but the electric motor is still trying to draw current (this is the out of phase problem typical of inductive loads such as electric motors).  The improvement in Power Factor achieved by such devices is real, and I understand it may even have benefits applying to the longevity of the electric motors involved (not sure about that one), but such Power Factor corrections simply cause less VA (apparent power) to need to be delivered for the same amount of real power (watts).  Unless your power company charges you for VA instead of watts there will be no difference in your bill (although it may be a tiny bit more due to losses associated with the capacitors themselves).  The vast majority of households in this country are charged for watts, not VA.  When you get to industrial power consumers, power companies may sometimes charge for VA, or at least add a penalty for low Power Factor energy use, in which case there can be an economic payoff for applying Power Factor Correction, but it still does not reduce real power (watts), only apparent power (VA).  It is desirable for the power company to have smaller VA values since the rating of the wiring and transformers used to deliver the power must correspond to VA values for those wires and transformers rather than watts.  In the half-wave rectifier example, the wires (etc.) must still be rated to carry the 120VA involved despite only 60 watts actually being transmitted, because 120 watts are only being transmitted 50% of the time, the other 50% of the time (per 60th of a second for 60Hz AC power), 0 watts are being transmitted.

 

Bottom line, how fast your power meter spins (and thus mow much energy you are using and how much your electric bill will be and how much energy is being generated and delivered to you from the power company) corresponds to watts, not VA.  Lower Power Factor numbers simply reduce the VA involved for the same number of watts.  Other than needing to have somewhat larger wires and transformers when the VA involved in a load is considerably higher than the watts, there's no downside to low Power Factor loads, certainly not of the magnitude suggested in the previous post.


Edited by bobkart - 6/17/2009 at 10:35 pm GMT
post #46 of 51

Thanks bobkart! This is going to be a good discussion...

 

It is a tricky business to measure the actual, true power consumption of reactive devices. There are "experts" who would agree with your assessment of VA versus watts and actual power produced at the plant to feed a reactive load, and there are an equal  number who would disagree with your assessment. Me? I'm not a degreed EE, but I know what I see in terms of actual electrical current being drawn, I know the actual voltage, and I'm still trying to sort out the conflicting opinions of the several "experts" I have queried (EE friends I know personally, as well as the EEs at the bulb manufacturers themselves) as to the true power consumption back at the plant.  It is obvious to me at this point that (a) it is not a simple matter to measure and calculate the true, bottom-line, net power consumption of reactive loads, in particular capacitive-type reactive loads, and (b) there are widely diverging opinions on what the true impact on the power production system is.

 

You are obviously knowedgable about things electrical. Have you ever instrumented any of these bulbs on an oscilloscope and observed the waveforms for both current and voltage going into the bulb? That might be one good way to determine the TRUE power consumed by a given bulb, regardless of anyone's general opinion of how much power is being consumed back at the plant. Of course, each bulb model from each manufacturer would have a slightly different circuit, so you'd have to instrument a number of different ones before being able to draw any reasonably accurate conclusions.

 

Similar to the old adage "a picture is worth a thousand words" the scientific/engineering corollary is "an experiment is worth a thousand opinions".

 

Also, can you explain exactly how the reactive power is "returned to the system" by these capacitive-type of power converter circuits in LED and CFL bulbs, where in the cycle the return of energy occurs, and the true amount of energy that is returned to the system? That would help a great deal in getting to the bottom of this issue, and one should then be able to calculate the TRUE efficiency.

 

One thing that everyone can agree on is that the electrical current required to feed a reactive load is greater than a simple "watts divided by voltage" calculation would indicate For incandescent bulbs, one can do that simple calculation and get pretty close to the true electrical current flowing through the wires. With reactive loads, that simple calculation doesn't work. The power company absolutely feeds more power down the lines to compensate for low-power-factor devices (i.e. reactive loads, be they inductive or capacitive), but the as-yet-unanswered question is "what is the true net amount extra they have to provide to compensate for reactive loads?". Even if they do only meter residences in watt-hours, not VA, they are having to burn some amount of additional energy back at the plant to feed the low-power-factor loads, the wires have to be larger, the line losses are greater, etc, etc, and they have to be compensated for all of those losses. So whatever they are metering you for is costing more per kWh than it would if there was always a power factor of 1.0

 

Thanks for your feedback, and I look forward to your answers to the questions above.

post #47 of 51
Sorry, I've been busy and have not had time to address your points.  But I will say now that in my opinion, the matter of low Power Factor loads is a minor one in the grand scheme of energy conservation.  Perhaps I am wrong about this, in which case I would be interested to see the evidence to the contrary.  Low Power Factor loads have been around far longer than LED lamps or even CFLs, so if it is an issue, it is not one that I would try to associate with LED lamps or CFLs, they may represent instances of the problem but they are not the problem.  The 5-10x reduction in power consumption obtainable through the use of LED lamps and CFLs vastly outweighs any marginal reduction in "power utilization efficiency" (whatever the issue might be there) that may be caused by low Power Factor loads.
post #48 of 51
Here's a link to some Q&A related to the matter of low Power Factor loads:

apps1.eere.energy.gov/industry/bestpractices/energymatters/articles.cfm/article_id=285
post #49 of 51

Thanks for the link bobkart.
 

The link addresses only inductive-type reactive loads on the grid and use of capacitors to reduce the peak currents and thus increase power factor. It actually does

work to do that with inductive-reactive loads, but whether it is economically worthwhile depends on the individual application. For some it is, for many it is not, and

unfortunately the sales types make more money if they ignore that dividing line. Hence the bad rap for capacitive power-factor-correcting devices. But technically, they do

work.

That said, the capacitive-reactive loads imposed by electronic ballasts and LED driver circuitry is different than inductive-reactive loads. I put in a call to a technical resource at Southen California Edison (SCE), our local power provider, and he finally called me back. His explanation (in simplified, bulleted form here):
 

 --  The main issue/concern/caveat with all reactive loads (either capacitive or inductive) is to be sure to size wiring, transformers, switches, etc. to handle the higher current in the circuit. In other words, design to VA, not W.

 --  The capacitive reactance is actually something of a help to the grid operators, because the capacitive reactance that feeds back from the electronic ballast or LED driver or switching power supply helps to cancel out the inductive loads that coil-based or rotating equipment feeds back to the grid.
 

  --  The magnitude of the inductive-reactance returned to the grid far outweighs the amount of capacitive-reactance that gets returned to the grid by electronics-based capacitive devices, hence the grid has banks of capacitors sprinkled around (usually up on the poles around here) to help negate the inductive reactance loads. That makes sense, because we all know that the heavy work in this world is done with rotating equipment, and there is a lot of it. But the utilit companies do actually appreciate (up to a point) the capacitive reactance that our bulbs feed back to the grid.
 

  --  The only way to truly determine the "net-net" efficiency of a capacitive-reactance device is to examine the voltage and current waveforms on an oscilloscope. By the term "net-net efficiency" I mean: Of the extra VA over and above the watts being burned, what percent of the extra VA is truly returned to the grid in useful form and what percent of it is lost as waste heat, or lost by inducing harmonic distortion back into the grid?
 

  --  In general, the largest loss imposed by the low power factor devices is the I^2*R loss (a.k.a. "heating loss") due to increased current that is required to be shipped down the lines, which, because I^2*R loss increases as the square of the current, is indeed significant. It's not the primary culprit, but it is not insiginficant nor should it be dismissed or ignored.
 

  -- The increased current necessitates larger wires, transformers, etc, which do take more material to build, ship and install, hence there is some unnecessary loss of energy & resources to make the heavier-duty components/materials.
 

  --  Some capacative-reactance devices have "dirty" or "hash" VA waveforms, nothing at all like the sine wave of a simple inductive device like a motor for example. The hash/dirty-waveforms represent inefficiency in that some of it "fights" the grid and it gets lost on its way back to the grid.
 

So, there is no doubt that the use of CFL and LED bulbs has resulted in a huge net savings in generated electricity in the world, therefor even low-PF bulbs are worth using (assuming they are inherently efficient in terms of light output per watt consumed). It appears to me now that you are correct in that the "extra" VA over and above the rated wattage is not a total loss to the world, some percentage of it is returned to the grid to do useful work. However, the four caveats to that good news are:
 

(1) Low-PF devices are still not as efficient as they could be, and there is no reason to not make them more efficient overall by designing them correctly.
 

(2) The only way to know a device's true efficiency for certain is to examine the waveforms with an oscilloscope on a case-by-case basis (each device will be different, based on its circuit design and its inherent performance).
 

(3) Some LED/CFL bulbs are way worse than others in terms of their net-net efficiency in returning their reactance to the grid.
 

(4) Losing an additional 2VA in a device that nominally consumes 20W of true power (effectively, burning & paying for 22W but receiving only 20W of use) doesn't sound like much in that context. But multiply that individual 2W by the 50,000,000 or so CFL/LED bulbs sold every year, and it undeniably does add up to be significant, and worth understanding the impact, if not controllling/minimizing that seemingly small loss in each individual device.

If every time you made a transaction at a store the clerk pocketed 10% of your change, you'd pitch a fit. Producing and using inefficient devices when there is a clear, easy alternative, is leaving money on the table, or letting the "clerk" (in this case, the bulb manufacturers and the power producers) skim off the top of your money. Either way, it costs the world overall a huge amount when you add it all up. Money lost, pollution/toxins released.
 

Based on the digging I've done, I am satisfied that CFL and LED bulbs with low PF do not waste as much energy as the first-pass "VA minus W" calcuation would lead one to believe. That said, without examining each device individually on a 'scope you don't know how efficient or inefficient it really is. And I stand by my opinion that leaving efficiency on the table is a foolish, unnecessary thing to do, and we should not accept it from manufacturers when they have a clear, easy alternative to meet the higher efficiency.

post #50 of 51
 I asked Sharp about the power factor for their new LED's and got this reply


Dear Mr. Bailey,

 

This is Kohei Kurosa from Sharp Corporation.

I apologize you for late respond.

 

You asked about the power factor of lamp factor,

but unfortunately, Sharp don’t open the information about power factor at this moment.

 

Best Regards,

Kohei Kurosa

Guess they figure it is none of our business. 

post #51 of 51
Hi bobkart & noneyet,

I have appreciated your discussion on power factor with the CFL & LED bulbs - very deep and informative.

Maybe you would like to weigh in on the  'anyone heard of powergard' thread. That is about the kind of power factor 'improvers' that supposedly save you big bucks. The kind where you just plug them into any available plugin. 
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