Talk:Electrical efficiency

Efficiency vs. efficacy

The term efficiency can only be used when the input and the output are the same thing.(ie electrical power in- electrical power out). If you put electrical power in but get out light, then this is called the luminous efficacy of the lamp.--Light current 04:16, 9 September 2005 (UTC)

I don't buy that.

Do you think that the only time we can use "efficiency" is when we deal with transformers?

If your statement were correct, you'd have to change not only one section, but the whole article including the title. I don't think you'll find support for that.

By all means, include a link along the lines of "efficiency, or luminous efficacy" in the article. They are synonyms here. The existence of one term does not prove that the other term is incorrect.

"Luminaires" is a strange word, unfamiliar to most people, and usually much more limited in meaning in English than for the French word, applied mostly to some particular kind of floodlight. The English "luminaries" would be a little better, but that is also usually used with a different meaning entirely. Gene Nygaard 12:28, 9 September 2005 (UTC)

Unfortunately, the term efficiency when refered to lighting is just WRONG!. I refer you to the Thorn Lighting Technical handbook, May 1978. Sect 1,1,3 on Basic lighting units. I quote ' EFFICACY (or luminous efficiency) of lamps is measured in lumens per watt (lm/w)'. Also it is generally true that, when a tranducer converts energy from one form to another the correct term is 'efficacy' not efficiency. In an encyclopedia, we should be careful to quote the correct scientific terms and avoid dilution and distortion of the terminology that can only lead to future generations having great difficuty understanding science and technology. See for example [1]--Light current 14:27, 9 September 2005 (UTC)

Weird! You shout that it is wrong, then cite a source which says that it is not—that efficiency and efficacy are synonyms in this context. Gene Nygaard 01:56, 10 September 2005 (UTC)

Obviously, they are quoting efficiency for those people who cannot undersand the term efficacy!. This is obvious. The correct term, is efficacy --Light current 07:13, 10 September 2005 (UTC)

only be used when the input and the output are the same thing.

Yes, we have electromagnetic energy flowing into the lamp, and electromagnetic energy flowing out of the lamp -- isn't that the same thing? --68.0.124.33 (talk) 10:59, 4 January 2008 (UTC)

The point is not whether energy is converted to a different form, but whether that form is desirable. The ratio (power output)/(power input) is only meaningful if power output is the useful product of the system. The efficiency of a transformer, a switch-mode power supply, or a radio transmitter is meaningful. The efficiency of a microprocessor is not, because the utility of a microprocessor's output does not depend on it's energy content. The case of the light bulb is somewhat more complex, as the utility of its output is partially, but not entirely determine by its energy content. For example, low pressure sodium vapor lamps are often used for street lighting because the sodium d lines are conveniently close to the peak of the human luminosity function. Their efficiency, however, is not drastically superior to that of other arc lamps. In closing, if you cannot express it as a dimensionless number, 'efficiency' is probably a poor choice of word. 209.189.245.116 (talk) 02:20, 1 February 2010 (UTC)

Vandalism

Reversion from Sillybilly's vandalism - Stop it or you will be reported and blocked. Also, stop making fraudulent claims of "Rampage" by others about your own vandalism. This is your final warning stop it or you will be reported.

--Theo Pardilla 04:02, 28 October 2005 (UTC)

Lighting efficiency inconsistencies

Section title shortened from: ==Lighting efficiency inconsistencies - someone please correct them, being called a vandal, I have to get YOU to do it==

The incandescent light bulb article has different efficiency/efficacy numbers. On that page, LEDs have 8-15% efficiency (not 80-90%), incandescents 2-4% (not 10%), xenon arc lamps 4-22%. These numbers are obtained by dividing the lumens/watt with the maximum 683 lm/W possible. Of course almost lamps are near 100% efficient at heating a room, via thermal conduction+radiation - what doesn't get converted into visible light, gets converted into heat, and even visible light ultimately gets absorbed and converted into heat.

Where the 80-90% LED numbers are obtained from? (Radiojon did the incorrect correction) And what's that electric kettle remark doing there, by itself? It looks kind of silly, but when I look at earlier versions of the page, such as that just before Radiojon's edits, the electric kettle looks nice and meaningful next to the lightbulb efficiencies. How has this page, being such a small page, gotten so disintegrated? Sometimes I'm paranoid, and sense intent.

• The maximum efficiency is 683 lumens per watt, multiplied by the photoptic function for each wavelength (λ) of useful light (no UV or IR) which is output from the source. That function is one of biology and frequency response of the average human eye. The photoptic fucntion is only the maximum 1.0 at λ=555nm (in roughly the middle of the visible light spectrum), and then drops off quite a lot on either side, to near zero at the edges. This means that the total weighted average across the dynamic range of the eye is close to 150 lumens per watt. Dividing by this much more practical and realistic number will give the proper figures. – radiojon 13:55, 31 October 2005 (UTC)

• • Sounds like awesome stuff. I'd love to read an article on the phototopic function. Also, would you care to modify the incandescent light bulb articles and add these numbers, perhpas with a second column? I've gone around, and even accused a wiki user of spewing nonsense in the negawatt and negawatt power articles, over these efficiency numbers of unknown origin, that seem to originate from you. Even so, assuming a LED has 15% efficiency on a 683 lm/W basis, using 150 lm/W as the 100% mark, that's still only 15%*683/150=68%, and not 80-90%. Where is this math wrong? In any case, from all this discussion what I'm getting is that the theoretical 100% lighting efficiency, or ideal lumens/W is such an arbitrary figure, that any lighting efficiency shold mention the 'bases', is it 683 base, or 150 base, just like logarithms don't make sense without knowing the base.

• Clearly there's some controversy about how to rate the efficiency of light sources. However, after doing some research I'm sure that the previously stated efficiency of LEDs (80%-90%!) was completely wrong. I couldn't find a reliable figure for LED efficiency, but I plugged in 25%, which seems about right. If someone has the knowledge (and references) to shed some real light on this subject (heh), please edit the article! KarlBunker 16:16, 5 January 2006 (UTC)

This article says:

• Incandescent light bulb: about 10% (15% for halogen lamps).
• Fluorescent light bulb: 30% to 40% (depending on the exact type).
• Light-emitting diode (LED) About 25% (depending on the type, and changing with rapidly developing technology).

I really think that if people "couldn't find a reliable figure" for something, they would be better off NOT just "plugging in" a guess with a {{Fact}} template!!! If you have a look at the Luminous efficacy article, you find some much better (and better argued and sourced) figures - like around 2% for incandescents, 7%-8% for CFLs, and 4%-10% for LEDs, with some advanced LED prototypes claiming 22%.

This article, though, is about Electrical efficiency in general. If you actually read the Luminous efficacy artcle, you will see that choosing light bulbs as the first, and only developed, example of some electrical thing's energy efficiency, was probably a mistake: Light output is hard to define taking account our human vision spectrum; light bulbs are hard to specify compared to isotropic radiators etc. Why not pick something manageable like a fridge, an electric motor or a rechargeable battery and base this article's example on one of those? Or at least use well-sourced figures for this example. --Nigelj 21:44, 9 May 2007 (UTC)

Narrow sense vs. broader system efficiency

(Lighting efficiency is a very difficult, complex subject, best avoided here as much as possible.)

I like this sentence: 'The term "efficiency" only makes sense in reference to the wanted effect.' However, we need the reader to know that "Electrical efficiency" is mostly a limited, directly technical term. Our world is full of transformers and other devices using and wasting energy when we think they are "off" (0% efficient, at best). And there are so many devices that are "on", using energy, pointlessly, with no one around getting any use from them. But all of that is rather beyond a simple concept of "Electrical efficiency" -- isn't it? -69.87.202.184 17:29, 29 May 2007 (UTC)

Electric fire

The article says that "an electric fire is 100% efficient in terms of converting electrical energy into heat." An electric fire is loud and bright, so either there's something important about the properties of an electric fire that I don't know or this statement is wrong. Either way, I think it requires a citation or deserves clarification. Rgiusti (talk) 18:43, 18 May 2016 (UTC)

I removed the statement. I seriously doubt that's correct. I anyone wants to add it back, just clarify and reference it. Rgiusti (talk) 18:50, 18 May 2016 (UTC)