Talk:Watt

Template:WP1.0 I don't think a minor character in a video game is worthy of being mentioned at the top of this page.

Dosage

Can someone who knows (you sparkies out there) add something on this page about lethal wattage, it is wattage that determines tissue damage isn't it?

Lethal "dosage" is complicated because the frequency of the electric current changes the effects on the human body. For example, you can be struck by a lightning bolt which has an incredible amount of power, and walk away with a few burns, or you can accidently touch a live wire cycling at 60 Hz and find that your muscles are unable to let go because the frequency keeps telling your muscles to clench, including your heart (killing you). I think I once saw a chart - DC is the least dangerous frequency, and the danger for the same Voltage increases to about 100 Hz, and then actually goes down a little and then levels off. I could be completely wrong about that though. Oh and one more thing - the statement "it isn't the voltage that kills you, it is the current" is completely wrong as far as I can tell. What typically kills people who are electrocuted is a heart attack. The electricity doesn't cook you, it just interferes with your body's signals until you don't work anymore. --Ignignot 14:47, 5 December 2005 (UTC)

This is probably not the whole story. I read in a newspaper a while ago that a "train surfer" was literally burnt to ashes in an instant when he came too close to the overhead line. I guess in this case the power mattered. (He might have been dead because of a heart attack half an instance earlier, though.) And also the voltage mattered: He didn't need to touch the wire because the distance a spark can travel depends on the voltage. --史慧开 (talk) 13:43, 20 April 2009 (UTC)

Volt-amps

what is the relation between KW & KVA

How do watts relate to volt-amps?

1 Watt = 1 Volt·Amp

Likewise, 1 kW = 1 kVA - Omegatron

Not so (at least in the normal usage). See power factor for the full explanation. 18.26.0.18 04:11, 3 Feb 2005 (UTC)

Yeah, I forgot. I hated that class. :-\ - Omegatron 05:45, Feb 3, 2005 (UTC)

In fact, if you derive the dimensions of both Ampere and Volt you will get the dimensions of the Watt, but I know the point about the difference between the real power and apparent power in AC circuits, however, in the same way that you can say that a Couloumb is an 'Ampere per second', you can also say that a Watt is a VA. Of course that you must pay attention to the context, but it isn't wrong. Afonso Silva 22:00, 19 May 2005 (UTC)

This seems like worthwhile information to place under the "Definition" section of the page. Any reason as to why it's not listed there, or should I add it? -Mbauman 20:11, 21 August 2006 (UTC)

MW*D

I disagree that megawatt days are a common method of reporting power output of power plants. Typically they are quoted in kilowatt hours, kWh, because that is how they bill their customers. --Ignignot 21:17, Feb 7, 2005 (UTC)

It may vary from country to country. Andrewa 19:12, 4 November 2005 (UTC)

North America uses kWh. I don't know about Europe or Japan or any other country. --Ignignot 14:39, 5 December 2005 (UTC)

Great Britain uses kWh for customer billing. However I don't see any reason why MW days wouldn't be used for power output. Someone find a reference or a power plant manager to confirm. 11:19, 13 March 2006 (UTC)

The EIA quotes in thousand MWh's on their website[1]. The NEB uses kWh, GWh, TWh, etc but not days[2] (pdf). The UK seems to be fond of "Million Tons of Oil Equivilent" which is a bizzare unit of measurement, but occasionally they use TWh [3] (pdf). The IEA (an international organization that monitors energy usage) quotes in GWh [4]. I think that while I have not been able to find non-English sources, I have shown that MW*D are not a common way of reporting power output. They might quote in MW, or kWh or MWh etc. but not MW*D. The only place I could find with reference to MW*d is for measuring the energy content of coal or nuclear fuel, which is more of a heat capacity or efficiency factor, and is extremely specialized. If there are more important examples (like the boilerplate of a generator being quoted in MW*d) then I would say leave it in, but since this method of quoting is so uncommon I'm going to remove it. By the way, I have a degree in electrical engineering and I work as an energy analyst, so I have some idea of what I'm taking about. --Ignignot 22:02, 13 March 2006 (UTC)

In relation to speakers and the like

Just curious what the watts actually do for speakers. Some surround sound systems are 100 watts or less and others are much higher (1000 for example). I imagine that the more watts the more power it all uses, so does that mean that the sound can go louder? or clearer? or what?

Loudspeaker#Efficiency has the answer to this. Also Audio power has a good explanation of RMS and PMPO. --Bkrosnov 11:43, 9 March 2006 (UTC)

1 kW·h = x kJ

There seems to be a bit of a revert war over whether a kilowatt hour is 3.6 MJ or 3.6 kJ. Let's work it out:

1 kW·h = 1000 W × 3600 s = 3,600,000 W·s = 3,600,000 J = 3.6 MJ

Indefatigable 15:15, 27 February 2006 (UTC)

The reason some people construe the kilowatt-hour as 3.6 kJ I noticed is due to the fact that these same people construe 1 kW as equal to 1000 J/ 1000 s , which is wrong. I attempted to solve this earlier by making clear in both the kilowatt and megawatt sections of the article that 1 kW = 1,000 J/s (NOT: 1,000 J/ 1,000s); and for megawatt that 1 MW = 1,000,000 joules per second. If someone were to construe a kilowatt as 1,000 joules for every 1,000 seconds then when that same person multiplies this false rate by 3,600 seconds the end (and false) result will be 3.6 kJ, instead of the correct conversion for kWh, which is 3.6 Megajoules. Therefore the edit made earlier clarifying what 1 kW equals and what 1 MW equals should be left alone and remain in the article. —Preceding unsigned comment added by 128.230.251.148 (talk) 21:38, 27 November 2007 (UTC)

64.185.152.169 —Preceding unsigned comment added by 128.230.251.148 (talk) 21:40, 27 November 2007 (UTC)

Typical household lamp

The intro said "A typical household, incandescent lightbulb uses 100 watts." That seemed way too much, so I changed it to 40-80 W. Or is 100 W normal somewhere? (let me guess - the US?) DirkvdM 08:36, 20 July 2006 (UTC)

That sounds like anti-American bigotry. While 100 Watt bulbs are available, most fixtures limit you 40-75 Watt bulbs. —The preceding unsigned comment was added by Mc6809e (talk • contribs) 01:18, 11 March 2007 (UTC).

100's are common in the U.S., tho getting less so. Are 20 W incandecants common anywhere? Changing to 40 - 100 W. --agr 14:38, 20 July 2006 (UTC)

I’ve been using 15 W incandecants in the US since the late 1970s/early 1980s. I’ve never had trouble finding them. Malirath (talk) 17:56, 18 June 2008 (UTC)

It's "incandescent", not "incandecant". And 15 watts for an incandescent bulb would be very dim indeed. Or did you mean fluorescent? Captain Quirk (talk) 02:15, 14 February 2009 (UTC)

A quick trip to Philip's website reveals bulbs for regular fixtures in 15, 25, 40, 60, 75, 100, 150, and 200W sizes. You can read just fine by a 15W bulb if it's close to the reading material, ie, task-specific, optimized lighting. They're common in ovens and such too. Renegrade (talk) 14:21, 12 March 2009 (UTC)

Excuse my spelling mistake. No I did not mean flourescent. --Malirath (talk) 18:10, 31 March 2009 (UTC)

Kilowatt-hour

kWh is a unit of energy, not power. Maybe it deserves a mention here, with a link to watt-hour, but the long discussion seems inappropriate. The stuff on mixed units of time also seems a bit POV. --agr 14:57, 20 July 2006 (UTC)

POV? How can something like that be pov? It does mix up three units of time, two of which are not SI units. That's worth poiting out isn't it? I won't put it back yet, because I don't feel like a revert war. And why do you point out that kWh is a unit of energy? DirkvdM 06:14, 21 July 2006 (UTC)

No response for about a week, so I'll put it back. DirkvdM 09:46, 27 July 2006 (UTC)

First of all, this article is about the Watt. There is a separate article for Watt-hour, which already points out that Wh is not an SI unit. The term "mix up" is POV because it implies something foolish or improper. The unit is widely used. Since the meter is now defined in terms of light seconds, one could say the same about km/h, I suppose. --agr 21:45, 28 July 2006 (UTC)

If 'mix up' isn't the right terminology, then change that to something that sounds less pov to you in stead of bluntly reverting the whole thing. If an article about an SI unit introduces a non-SI unit then that needs to be pointed out. And if something needs to be moved to another article, then do that, in stead of bluntly reverting the whole thing. In other words, you're not being very constructive. DirkvdM 08:10, 29 July 2006 (UTC)

I don't meant to be harsh, but I think the treatment of the non-SI issue in watt hour is adequate. If you feel additional information should be added, that is the place to discuss it, not here.--agr 03:39, 30 July 2006 (UTC)

Don't worry about my feelings, I've got a pretty tough skin. :) To me, only argumentation counts. Anyway, I still think the Wh/yr should be mentioned here, because it's also a unit of power, and derived from the watt. I'll give the same info in a shorter form, maybe that satisfies you. DirkvdM 11:04, 30 July 2006 (UTC)

MWh/yr seems to be what is used, particularly in alternative energy discussions. I agree it deserves a mention and conversion factor to Watts. There may also be a need to explain the distinction between peak and average power in the article. I wonder if MWh/yr is used in these contexts to make it clear that they are talking about actual energy produced during the year. --agr 19:51, 30 July 2006 (UTC)

Well, whether you use Wh/yr, kWh/yr, MWh/yr or whatever depends on what gives the most convenient values. It's all the same unit, multiplied by a power of 10, just written in a different form. Which is why we have an article on Wh, the basic unit, not the more common kWh. I'm not sure what you mean by that last sentence. DirkvdM 09:33, 31 July 2006 (UTC)

Right, but this article is about the Watt, not "units of power." If another Watt-related unit is to be mentioned at all, I think it should be in its most common form. There are a vast number of possible derived units that might be used somewhere (kWh/acre/month) and we can't cover them all. --agr 15:16, 31 July 2006 (UTC)

By that reasoning the kWh should also be removed. Unless you go by frequency of use. When I Google kWh I get 15 million results. For kWh/yr I get 75 thousand. Quite a lot less, but still rather much. When I Google kWh/acre/month I get none at all. Maybe you used a bad counter-argument because you deliberately exaggerated. Can you think of any better ones? If there is indeed a vast number of derived units that are used as much as kWh/yr, you've got a point. DirkvdM 12:36, 1 August 2006 (UTC)

I don't wish to argue about kWh/day vs MWh/day. Use your judgement. My point is that these are not the subject of the article, so any discussion should be brief.--agr 15:22, 1 August 2006 (UTC)

We don't seem to understand each other. I'm not talking about prefixes but about mentioning another unit than Watt. If there is room for Wh, then there should also be room for Wh/yr. These should be dealt with somewhere and the latter doesn't (yet?) deserve a separate article, so here would be a good place. Anyway, it's short enough now, isn't it? DirkvdM 09:06, 4 August 2006 (UTC)

volts * amps revisited

Mbauman inquired as to why this information wasn't included in the article, and I'm wondering as well. Should I add this information, or is there a specific reason that it has been omited from this article. Perhaps a subsection of conversations and/or relations to other units? RichMac 19:26, 9 October 2006 (UTC)

To review and expand on what was discussed above, the instantaneous power in an AC circuit is constantly changing. For convenience, the power quoted is usually the root mean square]] (RMS) average power. To accurately find the RMS average power, the current and voltage must be measured instant by instant, multiplied to find the instantaneous power, and the average power calculated. It is often more convenient to measure the RMS voltage and RMS current separately, and multiply the results. If the load is a resistor, this will be accurate, but the more capacitive or inductive the load is, the less accurate this approximation is.

When a "power" is given in volt-amperes rater than watts, it is a shorthand way of indicating that the RMS voltage and RMS current were measured separately, then multiplied to estimate the power; no correction for the inductance or capacitance of the load has been made. I think a link should be added to the volt-ampere article.

I fixed this posting after reading Omegatron's post below. --Gerry Ashton 20:56, 9 October 2006 (UTC)

Not "RMS power"; "average power". Average (apparent) power is measured by multiplying RMS voltage and current. — Omegatron 20:28, 9 October 2006 (UTC)

Actually, multplying RMS voltage by RMS current gives apparent power, which is equal to average power only if the load is resistive, but thanks for reminding me about the meaning of average power. --Gerry Ashton 21:00, 9 October 2006 (UTC)

Oh, of course. I work in a world of resistive loads.  :-) — Omegatron 21:05, 9 October 2006 (UTC)

Signal strength(?) vs. field strength

Ignoring gains, losses and free-space loss for the moment, field strength is typically defined as $\scriptstyle {V/m={\frac {V}{4\pi \,m}}={\sqrt {\frac {4\pi 30W}{4\pi \,m^{2}}}}={\frac {\sqrt {30W}}{m}}\,\!}$ or $\scriptstyle {W/m^{2}={\frac {W}{4\pi \,m^{2}}}.\,\!}$ I realize field strength defines the surface area of a "power sphere" (inversely, $\scriptstyle {W={\frac {W}{m^{2}}}4\pi \,m^{2}\,\!}$), but when attempting to define the strength of a signal at a receiver's input point (i.e., antenna connection point), isn't the situation like a ball resting on a flat surface?: The ball's contact to the surface is only at a single point (or very small surface area around the point), not the whole surface area of the ball, thus the more relevant measurement is the "strength/intensity" of the radius touching the flat surface (i.e., the particular "flux line"). Wouldn't the strength of the flux line be $\scriptstyle {{\frac {W}{m}}\,\!}$ and be considered the "signal strength" (signal strength seems to confirm that, but other articles and outside sources seem to use signal and field strength interchangeably)?

Let $W_{l}=W/m={\frac {W}{m}};\qquad \;W_{a}=W/m^{2}={\frac {W}{4\pi \,m^{2}}}.\,\!$

Let's say you have a 100kW station that is 1km away, giving the following results:

100,000W @ 1000m

100Wl

.007958Wa

If you have ten other stations with different ERPs and distances, five equaling W_l and five W_a,

	Line	Area
10,000W @ 100m	100Wl	.07958Wa
1000W @ 10m	100Wl	.7958Wa
100W @ 1m	100Wl	7.958Wa
10W @ .1m	100Wl	79.58Wa
1W @ .01m	100Wl	795.8Wa

	Line	Area
1000W @ 100m	10Wl	.007958Wa
10W @ 10m	1Wl	.007958Wa
.1W @ 1m	.1Wl	.007958Wa
.001W @ .1m	.01Wl	.007958Wa
.00001W @ .01m	.001Wl	.007958Wa

and you measured the strength of the signal right at the antenna connection point (but not through any antenna, just "barefoot") of a receiver, which set of five stations would equal the same strength of the 100kW station, the 100W_l or .007958W_a set? If it is W_l, would it be the same for any antenna attached or, as antenna length/size increases, is that when area (i.e., W_a) comes into play? Now let's say there is an eleventh, distant station, say 500km away (well beyond its prescribed field strength), coming in via unusual propagation——either via tropospheric ducting or sporadic E-skip——wouldn't that be the same 100W_l or .007958W_a?
Finally, incorporating free-space loss (where λ is wavelength), $W/m^{2}={\frac {W}{4\pi \,m^{2}}}.\,\!$ becomes $W/m^{2}={\frac {W}{4\pi \,m^{2}}}\cdot {\frac {\lambda ^{2}}{4\pi }}=W\left({\frac {\lambda }{4\pi \,m}}\right)^{2}.\,\!$.

Does that mean $W/m\,\!$ becomes ${\frac {W\lambda }{{\sqrt {4\pi }}\,m}}\,\!$ or just ${\frac {W\lambda }{m}}\,\!$?
 ~Kaimbridge~15:14, 22 April 2007 (UTC)

Perhaps the talk page for Radio propagation would be a better place to ask this question. --Gerry Ashton 18:02, 23 April 2007 (UTC)

Okay, I'll try over there ~Kaimbridge~16:44, 24 April 2007 (UTC)

Problem

Look for Kelvin in wikipedia. The smaller prefixes do not match (yocto etc.) :S — Preceding unsigned comment added by 194.204.127.248 (talk)

I have checked it and I found no difference. What did you refer? I only see that columns are swapped left-right. Rjgodoy 20:06, 3 June 2007 (UTC)

Science (Journal)

The OED also says "megawatt" appeared in a 28 November 1847, article in Science (506:2).

I was going to change [[Science]] to [[Science (journal)]] but then I noticed that Science (journal) claims, quite believably, that the journal was founded in 1880. Can someone check this OED statement? Mditto 21:03, 17 July 2007 (UTC) The OED cite mentioned is for 1947. I've corrected the date, though I don't really see the point of including the sentence. Dbfirs 18:46, 10 January 2009 (UTC)

SI multiples

I have nominated Template:SI multiples (transcluded or subst'ed in this article) for deletion on WP:TFD. Han-Kwang (t) 16:12, 23 August 2007 (UTC)

To kill a human

Brought this over from the volts page.

What would be the minimum amount of volts to kill a human? I am just comparing the ability of some animals and whether they would be capable to killing a person. Daily Rubbings 16:10, 12 June 2007 (UTC)

Just replace where it says volts with watts.

Voltage is not the lethal part, the ampage is what kills you. ralph86 14 Apr 2009 —Preceding undated comment added 19:42, 14 April 2009 (UTC).

Confusion in introduction

The introduction says that a watt is equal to one joule of energy per second. Isn't it more correct to say that a watt-second is equal to one joule? It's just a little confusing, especially after reading the section about "Confusion of watts and watt-hours". LK (t|c) 22:22, 15 November 2007 (UTC)

I'd say they mean the same. --Gerry Ashton 23:09, 15 November 2007 (UTC)

MWth and MWe

also posted at Talk:Longannet power station

This is a case where the strict usage SI units differs from usage in the electricty industry. As a worker in the UK electricity industry (and having also worked in the North American electricity industry, I recognise MWth and MWe, whilst W_th and MW_e are alien to me. --Stewart ^(talk) 08:58, 14 January 2008 (UTC)

It seems to me that incorrect usage by the electricity industry, if widespread, should be acknowledged. But that doesn't mean that we should make the same mistake ourselves elsewhere on WP. Can you supply a reliable source for this usage? Thunderbird2 (talk) 09:01, 14 January 2008 (UTC)

Here are two for starters CANDU owner's group page for Bruce Power and EDF Nuclear Generation. --Stewart ^(talk) 18:27, 14 January 2008 (UTC)

Thanks. That is already more than there are on this page for MW_e. But they are both from commercial power companies, right? Do you know of an industry standards body or something similar that may confirm your version of these abbreviations?

In parallel, can anyone back up the statement that the correct abbreviation for this quantity is MW_e (and not MWe)? If not, I suggest converting to MWe on the basis of the sources offered by Stewart. Thunderbird2 (talk) 19:23, 14 January 2008 (UTC)

I found this, which further supports Stewart's position. It seems I reverted his changes too hurriedly. Sorry :-(

Notice though that he uses MWt rather than MWth for "thermal". Should both be mentioned? Thunderbird2 (talk) 19:36, 14 January 2008 (UTC)

These are SI units. They're just SI units with labels tacked onto them. A "megawatt electrical" is still a megawatt; the symbol just differentiates which part of the output you're talking about. Same as "volts peak-to-peak", written as V_P-P or "volts rms" written as V_rms. They're still volts. The e and th are not part of the unit; they're labels, which is why they're written in subscript.

It's common in engineering and math to write labels as subscripts when formatting things "properly", but simplify to plain lowercase when lazy or when the medium doesn't allow subscripts. "V_out" becomes "Vout" for instance. I think that's all that's going on here. For example, in [5], they use "GW_eyr" in the main text, but simplify to "GWeyr" on a chart's axis, presumably because their chart-plotting program doesn't support subscripts there. This isn't standardized that I'm aware of; MW(e) is another way to write it without subscripts.[6] [7]

Other examples of the more properly formatted "MW_e" and "GW_eyr": [8] [9] — Omegatron 00:25, 19 January 2008 (UTC)

Heh. This document even calls them "subscripts" while writing them on the same line as the text. — Omegatron 00:28, 19 January 2008 (UTC)

As far as I know, what is and is not SI is defined in the official brochure. On page 132 of that brochure it says "the unit symbol should not be used to provide specific information about the quantity" and in the margin it says "For example: The maximum electric potential difference is U_max = 1000 V but not U = 1000 V_max" (emphasis added). In the preface (page 101) it says the "main purpose [of the brochure] is to define and promote the SI" (emphasis added). Unlike some publications, I couldn't find any statement that sentences containing words such as "must" or "shall" are mandatory while sentences containing the word "should" are merely recommendations, so it isn't clear to me if V_max is positively outside of SI or just not recommended. --Gerry Ashton (talk) 01:41, 19 January 2008 (UTC)

The attachment of suffixes, whether or not as a subscript, is not permitted by the (commonly violated) SI rules. I made the changes because the only reliable source I could find used the MWe format. If other reliable sources mention MW_e as preferred then perhaps the article should mention both. Thunderbird2 (talk) 10:38, 19 January 2008 (UTC)

I provided sources right above your comment. — Omegatron 15:10, 19 January 2008 (UTC)

Yes, I didn't mean to suggest otherwise. Those sources are a good start, but they don't prove that MW_e is preferred to MWe. I wondered if there might be an umbrella organisation for the power industry that defines these abbreviations. Any suggestions? Thunderbird2 (talk) 15:35, 19 January 2008 (UTC)

I imagine "MWe" is more common, but MW(e) and MW_e are also used. — Omegatron 23:49, 20 January 2008 (UTC)

IEEE also says that this usage is incorrect:

Attachment of letters to a unit symbol for giving information about the nature of the quantity is incorrect: MWe for "megawatts electrical (power)," kPag for "kilopascals gauge (pressure)," Paa for "pascals absolute (pressure)," and Vac for "volts ac" are not acceptable. If the context is in doubt on any units used, supplementary descriptive phrases should be added to make the meanings clear.

— IEEE Standard Letter Symbols for Units of Measurement

On the other hand, everyone still uses them:

• http://www.google.com/search?q=site%3Aieee.org+MWe
• http://www.google.com/search?q=site%3Aieee.org+MWt+plant
• http://www.google.com/search?q=site%3Aieee.org+MWth
• http://www.google.com/search?q=site%3Aieee.org+VAC

— Omegatron 23:49, 20 January 2008 (UTC)

I think the best solution is to quote the IEEE standard in the article (do you have a more complete reference than just the title?) and then state that the advice is not always followed. Do you agree? Thunderbird2 (talk) 07:17, 21 January 2008 (UTC)

The article already points out that the International Bureau of Weights and Measures considers the symbols incorrect; do you think the IEEE would be better, since that organization is more directly related to electricity? --Gerry Ashton (talk) 07:56, 21 January 2008 (UTC)

As these are not SI units it doesn't seem appropriate to start with BIPM. If they are (as Omegatron argues) IEEE units, my view is that the article should introduce them first in an IEEE context (as subscripted units like MW_e); then go on to say that it is common practice to use suffixes instead (MWe) even though IEEE disaproves (a bit like use by the same industry of kWh in place of kW·h); and end by saying that SI permits neither form. Does that make sense? Thunderbird2 (talk) 08:10, 21 January 2008 (UTC)

I'm not convinced there is one policy toward MW_e and a different policy toward MWe. The IEEE standard indicates MWe is incorrect, but does not suggest MW_e as a replacement, instead it says to use a descriptive phrase. I suspect this is a case of the authors of the IEEE standard and the editors of the IEEE journals not communicating with each other. --Gerry Ashton (talk) 08:33, 21 January 2008 (UTC)

In that case I misunderstood what Omegatron was saying. If your interpretation is correct, that makes IEEE and BIPM consistent with one another (in that neither subscripts or suffixes are permitted). Do you have a copy of the (IEEE) standard? Thunderbird2 (talk) 11:48, 21 January 2008 (UTC)

No, I don't have a copy. It is available for a fee at the IEEE web site. --Gerry Ashton (talk) 22:29, 21 January 2008 (UTC)

I had a look around and discovered I do have a copy. The standard permits some subscripts, but only to disambiguate units that are quantitatively different but share the same name (giving Btu_IT, cal_th and gal_US as examples of this, to distinguish them from Btu₆₀, cal₁₅, gal_Imp). My interpretation is that MW_e is not permitted by this IEEE standard. Thunderbird2 (talk) 23:02, 21 January 2008 (UTC)

A related point is that IEEE explicitly permits use of the abbreviation Wh to mean watt hour, p5:

• "The dot may be omitted in the case of familiar compounds such as watthour (symbol Wh) if confusion is unlikely"

Ah for ampere hour is also mentioned explicitly (p8). Thunderbird2 (talk) 23:12, 21 January 2008 (UTC)

The full document reference is:

IEEE Standards Coordinating Committee 14, IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units), IEEE Std 260.1-2004 (Revision of IEEE Std 260.1-1993), 24 September 2004.

Thunderbird2 (talk) 23:17, 21 January 2008 (UTC)

Mention of an auto engine in the introduction

The introduction states that an automobile engine produces 25kW when cruising. What automobile? With what engine? At what cruising speed? A boxy van cruising at 70MPH will be using considerably more power maintaining speed than a sleek coupe at 60MPH. Without any details, the sentence is meaningless. 134.121.241.149 (talk) 03:18, 1 April 2008 (UTC)

I think it's an approximation intended to give lay people some idea of the size of output described in terms they can understand, in other words a car produces about 25kW as opposed to an electric fire (about 1kW) or a ship (about 1mW). In this context I would think it does the job without needing to be too precise. Britmax (talk) 13:49, 2 April 2008 (UTC)

Request to add milliwatt and microwatt to article

Milliwatt and microwatt are used in the article Mobile phone radiation and health (and in other places; see Special:WhatLinksHere/Milliwatt and Special:WhatLinksHere/Microwatt). I would like to suggest that these be added to the SI Multiples section. --papageno (talk) 03:08, 2 June 2008 (UTC)

Y These two units have been added to the article. --papageno (talk) 21:40, 17 June 2008 (UTC)

Incorrect use of terms...............

The article makes a few references to "uses" x Watts or "generates" x Watts etc.

The first line actually says "It measures a rate of energy use or production"

Is this strictly correct? A 100 Watt lightbulb doesn't "use" 100 Watts. A 100 Watt generator doesn't "generate" 100 Watts.

A 100 Watt lightbulb "converts" 100 Watts of electricity into 100 Watts of heat and light. A 100 Watt generator converters chemical energy into electricity.

Surely the unit "Watt" isn't the rate of "using" or "generating" energy. It is the rate of "converting" it? —Preceding unsigned comment added by 79.75.13.123 (talk) 13:43, 17 August 2008 (UTC)

Although the processes could be thought of as conversion, the words "use" or "generate" are also appropriate, and easier to understand for people without education in physics. Also, neither lightbulbs nor generators do anything with the remains of James Watt; they use or generate electrical power, which is measured in watts. --Gerry Ashton (talk) 17:13, 17 August 2008 (UTC)

I agree with the previous unsigned comment. Energy doesn't, by any stretch of the imagination, get used or generated. It is converted. And power is the rate of that conversion. To state the energy is used or generated is completely incorrect. I take your point about the capitalisation but feel its rather pointless and trivial. —Preceding unsigned comment added by 86.140.92.253 (talk) 11:18, 30 August 2008 (UTC)

Electrical energy is generated (by conversion of mass or another form of energy of course), and incandescent light bulbs certainly use electrical energy (by converting it to heat + a small amount of light). I don't see a problem with using everyday terms in this way. Dbfirs 18:51, 10 January 2009 (UTC)

Quadrillion

Do we really want ambiguous terms like this in a scientific article? If we want to explain in simple terms, would it not be better to use "thousand million million", or just write out the number? Dbfirs 18:59, 10 January 2009 (UTC)

Is it really ambiguous? Is quadrillion currently used to mean anything other than 10¹⁵? --Gerry Ashton (talk) 19:58, 10 January 2009 (UTC) Corrected 18:30, January 13, 2009.

Long and short scales –OrangeDog (talk • edits) 10:44, 13 January 2009 (UTC)

I was taught (and still use) the fact that a billion is 10¹² (long scale), but I agree that this usage is getting less common. I don't think scientists use quadrillion at all do they? I have just found usages of quadrillion meaning 10¹², 10¹⁵, 10¹⁸ and 10²⁴. It's a bit like "zillion"! - With this amount of confusion, I suggest we just use powers of ten. Dbfirs 11:17, 13 January 2009 (UTC)

"Quadrillion" has to mean 10¹⁵ at least. Also see Quad (energy). Names of large numbers says a long-scale quadrillion is 10²⁴. This difference isn't going to affect the way I balance my checkbook. --Wtshymanski (talk) 14:49, 13 January 2009 (UTC)

Nor my bank balance! The 10¹² was a mistake, but it illustrates that the word means little to most people, and different values to different speakers of English (and not just a difference between American and "Old English" usage - the 10¹⁸ was in Serbia). That's why I think we should avoid using the word in other scientific articles. Dbfirs 08:06, 14 January 2009 (UTC)

I'm reminded of the punchline of the old Newfie joke "Millions? Me son, d'ere's T'OUSANDS!". "Quadrillion" is perfectly well defined - even if the proofreaders at my local newspaper don't instantly recognize the difference, I do, and I'm comfortable with it in appropriate technical context. If we only put in the words that everyone knew, our Wikipedia vocabulary would be ...impoverished? --Wtshymanski (talk) 14:55, 14 January 2009 (UTC)

Supposedly unclear sentence

The IP user 79.86.198.29 altered a sentence to read (addition underlined):

The average power usage by humans (about 15 TW) is commonly measured in these units [Sentence not clear: "by humans" - individuals per day? planet-wide per week?].

Of course, the correct way to ask about what the reader thought was a problem was to edit this talk page, but let's pass over that and discuss the sentence.

Fifteen terrawatts is the same as 15 terrajoules per second. The basic resource that is being used up is energy, which is measured in joules. Power is a rate of using energy, and is measured in watts. As to whether it applies to all humans or per human, I would have thought the overall context of the article would have made it obvious that 15 TW is far too much to be used by one human, but we could adjust the sentence a little if people think it isn't obvious. --Gerry Ashton (talk) 14:41, 23 January 2009 (UTC)

For a non-specialist that wouldn't neccessarily be obvious. Maybe: "On average, the human race consumes energy at a rate of around 15 TW" would be better. --Ralph86 (talk) 19:54, 14 April 2009 (UTC)

What's a year?=

The article says right now

+ Often energy production or consumption is expressed as terawatt hours per year. As one year contains about 8,765.82 hours, one terawatt hour per year equals about 114,08 megawatts.

But the sorts of organizations that report energy in TWh/yr use a civil calendar of 365 or 366 days, giving either 8760 hours or 8784 hours. Better to say "about 114 MW" which is enough significant figures. --Wtshymanski (talk) 14:32, 24 February 2009 (UTC)

This sentence really confused me at first; I didn't get what the unit conversion being done was. I eventually realized it was saying that to *get* a terawatt-hour over a period of one year, it would take being able to *run at* 114.08 megawatts for a period of 1 year. Is there a way to reword the sentence to make that more clear for casual readers like me? Perhaps...

Often energy production or consumption is expressed as terawatt hours per year. As one year contains about 8,765.82 hours, one terawatt hour per year would be the equivalent of providing about 114,08 megawatts of generating capacity for a period of one year.

or...

Often energy production or consumption is expressed as terawatt hours per year. As one year contains about 8,765.82 hours, one terawatt hour per year would be the equivalent of a 114,08 megawatt plant operating at full capacity for one year.

Whatcha think? JorenCombs (talk) 09:36, 20 April 2009 (UTC)

Request to add KWh_e and KWh_h

The terms are used in CHP to define the generators output in heat and electricity. User:ralph86 14 apr 2009

abbreviation

Insofar as it's watt, shouldn't the abbreviation be w? This leaves W for west and tungsten. I note some folk mistakenly writing K to mean a thousand. —Preceding unsigned comment added by 86.148.170.81 (talk) 08:08, 19 April 2009 (UTC)

The CGPM has decided the symbol is "W". Notice the upright type. It is capitalized because it is named after a person, James Watt. The spelled-out unit, "watt", is not capitalized to help distinguish the person from the unit. "West" and "tungsten" are not units of measure and it should be easy to distinguish them from "watt" by context. --Jc3s5h (talk) 15:12, 19 April 2009 (UTC)