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Talk:Alternating current/Archive 3

< Talk:Alternating current
Latest comment: 2 years ago by 2600:2B00:7420:8800:8456:59B7:9E31:C791 in topic Tesla?
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Comments and suggestions

Latest comment: 9 years ago1 comment1 person in discussion

I read the article and I didn't like it because it's not very well written. It is also somewhat unorganized. Most of all, I don’t like the order of the sections that make this article because they do not flow properly and they are not conducive to learning, especially for someone that does not know much about alternating current. Of top of it, I feel there are unnecessary disquisitions that lead to hard-to-understand concepts that are not that complicated.

Personally, I think this article should be reorganized: history should be first, mathematics second and transmission third. The discussions about frequency should be merged in a single section and could be placed between mathematics and transmission.

I have a few comments:

1. The sentence "This means that when transmitting a fixed power on a given wire, if the current is halved (i.e. the voltage is doubled), the power loss will be four times less." is not clear. It's clear that if current is halved power will be four times less but it's not clear to me how you can half the current by doubling the voltage if V=R*I. V and I are directly proportional. I think a clear explanation is required.

2. The expression "Mathematics of AC voltages" is a misnomer. There is no such thing as alternating current voltage but only alternating current or alternating voltage. This is somewhat awkward, even more when the article is about alternating current but the equations in it are for alternating voltage. There should be consistency.

3. The first equation under the section "Mathematics of AC voltages" only applies to sinusoidal functions. This is not stated explicitly so the statement cannot be considered true in general. The equation should use f(t) instead of sin(ωt).

4. The subsection entitled "Power oscillation" is not clear. I don't even know why it's there.

5. Something is wrong with "In their joint 1885 patent applications for novel transformers (later called ZBD transformers)". I think the sentence is missing a word between "for" and "novel" which is "their".

ICE77 (talk) 03:04, 6 November 2016 (UTC)

Time unit

Latest comment: 8 years ago6 comments2 people in discussion

Next to the figure of a single sinusoid cycle (1 crest followed by 1 trough of the curve), the text says "t is the time (unit: second)." The problem is that single cycles of alternating current are 60ths of a second, not seconds. Shouldn't it read "unit: 1/60 second"? The Mysterious El Willstro (talk) 03:06, 6 May 2017 (UTC)

Nope, correct as written - the formula applies at t= 1/60th of a second, t=1 second, t=32767 seconds, etc., over many multiples of one cycle...the sine function repeats every 2 * pi/omega seconds. --Wtshymanski (talk) 03:26, 6 May 2017 (UTC)
Nevertheless, alternating current normally cycles at t=1/60 second. The Mysterious El Willstro (talk) 03:36, 6 May 2017 (UTC)
The world is a very large place. In some foreign lands, they reverse the flow every 1/50th of a second and consider that to be "normal". Crazy, eh? I hear some of these places don't even pay taxes to Washington. --Wtshymanski (talk) 03:50, 6 May 2017 (UTC)
I didn't say anything about paying taxes to Congress in Washington. I'm well aware of varying international standards for voltage in the consumer grid (that is, after passing through a residential substation), but that's voltage, which is an entirely different matter from cycle time. The Mysterious El Willstro (talk) 04:16, 6 May 2017 (UTC)
Yes, voltage and frequency are different things. This is either unutterably profound or bleed'n obvious. Just in case you're not shining me on, you are aware that a lot of the world used 50 Hz? And other frequencies are, and have been, used? See Utility frequency. --Wtshymanski (talk) 05:06, 6 May 2017 (UTC)
Latest comment: 8 years ago1 comment1 person in discussion

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Latest comment: 8 years ago1 comment1 person in discussion

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This article is written ONLY for experts

Latest comment: 8 years ago9 comments7 people in discussion

Wikipedia is an encylopedia. This article is written for people who already know what Alternating Current is and how it is generated. The main article should be simpler and should explain to a common lay person, how alternating current is generated and functions. Advanced discussions should follow or be spun off to another article. And, no I can't be the one to fix it, I'm not qualified to explain the concept, I came to this article to firm up my own understanding. Gdewar (talk) 21:21, 12 April 2008 (UTC)

OK, but some more specific comments would be very helpful; all the people who've been editing to this point seem to think they've explained the subject clearly and if we *haven't* then your specific criticism will be valuable. What,specifically, is wrong? Start with the introduction. When do you start throwing your hands up in the air? C'mon, help us out. --Wtshymanski (talk) 23:31, 16 April 2008 (UTC)


I agree with Gdewar. The whole thing is rather uninformative, but I got really rankled when I came to

For three-phase at utilization voltages a four-wire system is often used. When stepping down three-phase, a transformer with a Delta primary and a Star secondary is often used so there is no need for a neutral on the supply side.

What I came to this article hoping to find out was: how the electrons move in the wire, what's happening at the power station to make them do that, something about hot and neutral, and what's the deal with the two different legs coming into my circuit box. And maybe something about how that back-and-forth electron motion is used to make appliances go. A good starting point for explanation may be to assume knowledge of DC, since that's simpler and easily understood by analogy to plumbing. The distinction between hot-and-neutral vs. negative-and-positive might also be worth a mention. Brock (talk) 19:32, 19 November 2008 (UTC)

I'm not sure if this belongs here, but I know it isn't supposed to be part of the main article now. This is the simplest explanation of Three Phase Alternating Current I can come up with for you...

"The dynamos used to generate North American alternating current are designed to switch polarity 60 times a second, so they build a maximum voltage charge and drop it and then reverse the charge to a maximum negative voltage and drop it and so on, 60 times a second. This creates a high voltage current in the transmission line which reverses direction 60 times a second, saving the transmission line from amperage loads over long distances (electrons travelling in one direction the length of the transmission line will be found in Direct Current only, and they heat the wire easily) and result in high voltage without overheating the transmission line. Since there are down times, when the voltage drops and reverses polarity, it is more efficient to run three dynamos out of phase, and so transmit 180 voltage cycles a second, each of the three lines providing a voltage peak in sequence 60 times a second. Depending on how much power the customer requires, these 3 power lines are available, using transformers to lower the supplied voltage down to the minimum typical household voltage of 110 volts per line. Only two of those lines are delivered to the typical household, since being out of sequence the voltage differential between the positive and negative phases of the two 110 volt lines used to power your clothes dryer and stove will add up to a 220 volt differential for the heavy motors and resistors of the dryer and stove, which is why those 220 volt appliances are served by power from both sides of your circuit breaker panel (each side being connected to only one of the incoming 110 volt phase lines), while the rest of your appliances and lights will be served by only one line providing a single 110 volt cycle. The extra wire going to your appliances is the return to ground wire, which returns to your circuit breaker panel containing the voltage grounding line for the power lines in from the street (without grounding there is no voltage differential available to generate electron flow). This ground wire inside the circuit breaker panel is not the same thing as the ground wire in an appliance. The ground wire in an appliance, which you attach to a ground connection of your own choosing, such as the already wired-to-ground junction box in your wall, will simply divert stray electron flow away from your own body if the appliance short circuits and starts delivering stray electricity to the shell of the appliance, which you might touch." —Preceding unsigned comment added by 75.157.220.85 (talk) 19:48, 22 November 2008 (UTC)

I understand your need for a simple explanation, but quite a lot of what you have written above is simply not true (though some is). I will try to insert a brief paragraph containing just the true bits, so that we don't upset the experts. One difficulty is that the numbers you quote are not true for my country, and this is an international encyclopaedia. Dbfirs 20:25, 22 November 2008 (UTC)
(later) I'm struggling to improve on the introduction. I'm not sure that even experts fully understand the quantum mechanics of electron flow. The plumbing analogy is an over-simplification, even for DC. It is good for a children's encyclopedia, but would not be appropriate in this article. Perhaps we should have a new article: a simple explanation of electricity? Dbfirs 22:55, 22 November 2008 (UTC)


Here's something I wished was editted in. (it should be edited into every relevant wiki page)

Can we get a practical world example and solve?

-So the theory was explained, and so was the equation for Power Loss. The power loss and power transmitted equations are identical so now I'm confused. With those equations being the same, then all power should be either lost entirely or transmitted entirely, so everything in AC current works and doesn't work at the same time. That isn't the case of course, I'm just not able to put the concepts into the practical world from the information listed on the wiki-page. Thanks (for future edits)! --Viriality (talk) 23:37, 18 October 2017 (UTC)

I just had a look and the two equations are not identical. The variables are explained in the text; that could probably be improved. I think that it needs a picture.Constant314 (talk) 23:53, 18 October 2017 (UTC)
I added a picture to explain the variables. Hope that helped.Constant314 (talk) 16:48, 19 October 2017 (UTC)

Common meaning

Latest comment: 7 years ago5 comments2 people in discussion

The common meaning of alternating current is for power distribution. The other referred to types are sometimes technically alternating current (and usually not). My edit trying to clarify the former was reverted as being awkward wording.......that could be true but we should try to work that common meaning clarification in. North8000 (talk) 02:54, 24 January 2018 (UTC)

The article already has more text about electrical power than any other form of AC, which is how it should be. The sentence which was changed, made a true statement about the waveform in AC power circuits. But here are many other types of AC. The sentence, as changed, unduly focused on AC power circuits. Constant314 (talk) 13:09, 24 January 2018 (UTC)

As an indicator of the general meaning of the term, I just googled "alternating current" and looked at the top 20 hits (not counting Wikipedia) and 100% only talked about power distribution. IMO this article gets too confusing by going off into the weeds of a lot of other specialized areas that are generally not called alternating current. And many of them (data transmission) described as AC are usually not AC, they are in essence one grounded conductor and another conductor with varying DC, and current flow is only in one direction. Sincerely, North8000 (talk) 13:41, 24 January 2018 (UTC)

There is a large community that considers AC includes a lot more than just power transmission. This article is about AC in a larger sense than power transmission. The lede should reflect the contents of the article. Google hits are irrelevant. The article should cover the most common meaning and should cover less common but still widely used meanings. The casual reader will not be harmed by finding out that there are common uses of AC other than electric power transmission.Constant314 (talk) 16:21, 24 January 2018 (UTC)
I agree with 90% of your post and disagree with only one point in your post.....IMO such an overwhelming picture from a google search, and the source content of the top 20 results is indicative of the common meaning. But, not that you have any obligation to do so, your post does not address the points in my 13:41 post. Sincerely, North8000 (talk) 16:49, 24 January 2018 (UTC)

Tesla?

Latest comment: 2 years ago10 comments7 people in discussion

Granted, I'm not a scientist but I'm pretty sure that Tesla was very important in the history of AC yet he's only briefly mentioned once in the history section of this article. Does anyone with more knowledge on the subject think more about him should be added? — Preceding unsigned comment added by 2600:1700:69C1:2A00:79D6:BABB:C3E6:AE3C (talk) 22:21, 4 July 2018 (UTC)

I think so. North8000 (talk) 22:52, 4 July 2018 (UTC)
It was strange re-researching some hydroelectric energy facts that Westinghouse and Edison created AC electricity but not all the others. Not sure of the story that was Sad and Ironic that Edisons invention of limited DC Energy caused him to argue against a proven better transmission of power of three wire AC power. Was it because of pride, money or envy who knows? The Diligence and life pursuit of a Syrian Immigrant Scientist backed and controlled by Edison and Westinghouse had to be like the boss who pushes for more only to get rich of your accomplishments, dedication and hard work. I agree with previous comment the whole history section needs to be expanded significantly. 2600:2B00:7420:8800:8456:59B7:9E31:C791 (talk) 10:46, 22 February 2023 (UTC)

I think that the previous section is relevant to this. The common meaning of AC is power distribution, not other forms of signals which could technically be called AC but seldom have that term applied. And Tesla was quite prominent in that. North8000 (talk) 12:42, 5 July 2018 (UTC)

  • Sources? It really comes down to that - need reliable sourcing from non-Tesla books as to his contribution to AC... and I don't think you are going to find much. AC development was very important to Tesla but Tesla was not very important to AC development. His only large scale involvement was that he held a key AC motor patent for 17 years, and that was because it was backed (enforced) by Westinghouse and then by GE in a patent sharing agreement. Historians (not "Tesla historians") note that Tesla never originated the ideas he developed, and he never developed them to anything useful... all done by other people. He was more of an ideas middle man who thought big. Unfortunately allot of his big ideas were fantasy's in his mined and were therefore not a big contribution to the development of AC. Fountains of Bryn Mawr (talk) 18:43, 5 July 2018 (UTC)
@North8000 I have no problem with adding more material about AC power distribution and its development, but I disagree that "AC" is seldom applied to other signals. It is a very common term in the world of electronics. I would not want to see that usage depreciated.Constant314 (talk) 00:24, 6 July 2018 (UTC)

I'm just throwing some thoughts out that might be helpful. I'm not going to worry about it much beyond that. That said, IMO saying "little influence on AC in the broadest sense" IMO is built on the false premise on the common use of the term that I was challenging. That said, IMO Tesla was very prominent in the history of AC power distribution primarily due to his prominence in the AC vs. DC battle. Sincerely, North8000 (talk) 16:08, 6 July 2018 (UTC)

Tesla actually didn't have a "prominence in the AC vs. DC battle", that's a bit of a misnomer. The War of the currents was already raging before he entered the AC business (received his first patents) and there was no "Tesla poly-phase system" until 1893, a year after the War of the currents ended. The WOTC started out as the people of New York vs the arc lighting companies and morphed into Edison vs Westinghouse (who was using a William Stanley Jr. designed system at the time). None of that had anything to do with Tesla. Fountains of Bryn Mawr (talk) 19:37, 6 July 2018 (UTC)

"Effective power" listed at Redirects for discussion

Latest comment: 4 years ago1 comment1 person in discussion

  A discussion is taking place to address the redirect Effective power. The discussion will occur at Wikipedia:Redirects for discussion/Log/2021 July 8#Effective power until a consensus is reached, and readers of this page are welcome to contribute to the discussion. -- Tamzin (she/they) | o toki tawa mi. 12:54, 8 July 2021 (UTC)

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