Talk:Alternating current/Archive 2

Archive 1

Archive 2

Archive 3

Descriptions of 120/208, 277/480, etc.

Might I ask someone to add a description of what 120/208, 277/480 refers to? I only understand single-phase, but I think it's phase-to-neutral (ground) versus phase-to-phase? Is WikiAnswers correct? MrBell ^(talk) 22:59, 22 April 2010 (UTC)

That's really more a convention for describing distribution systems than a point for this article, which I think is meant to talk more about fundamentals. If there's two voltages available in the same distribution system, it's often the case the system voltage is given with a slash or other dual indication. In single-phase systems there is a center tap and the voltages betweeen the two energized conductors are twice the voltage between an energized conductor and the center tap - so we get designations such as 120/240. In three phase systems, the voltage between any two conductors is sqrt(3) times the voltage between a conductor and the "neutral" reference point - so you might have a distritbution system designated "120/208" - 120 volt loads can be connected from an energized conductor to the system neutral point, and 208 volt (single- or three-phase loads) can be connected to the energized conductors.

You find the same thing at medium voltages used for distribution, for example you may find a system designated 24.49Y/14.4 kV - if you have industrial customers in the area who need 3-phase power, you run 3 wires out and there's 24.49 kV between the wires, but if there's only residential loads, one pair of wires (or a wire and an earth return) suffices, and the single-phase transformers are connected single-phase to neutral (ground) at 14.4 kV. --Wtshymanski (talk) 13:28, 23 April 2010 (UTC)

Great explanation, thanks. Based on your comment, would you recommend that this info be proposed/added to Electricity distribution instead of here? MrBell ^(talk) 15:12, 23 April 2010 (UTC)

About a link

I added a link to Garyfallidou.org/en_electricity.html, a page containing a video which explains (to kids) how free electrons act in a simple circuit. In case of: No current, DC current and AC current. The link removed by Wtshymanski. I believe that Wikipedia (any encyclopedia) is for people (specially kids) who are trying to get knowledge and not for people who already have the Knowledge. The link added to Electric current-Direct Current-Alternating Current. Removed from Electric current - Alternating Current. Lambrosus —Preceding unsigned comment added by Lambrosus (talk • contribs) 18:05, 26 May 2010 (UTC)

Explanation about neutral 0 and electrocution

What is the reason for an AC circuit to have a neutral wire (0)? I mean the alternative current is passing through the consumator and returns usually 50 times per second (50HZ) but why it won't work if the signal don't return? Does the return signal contains an unused energy (like some watts which the consumator don't need)? Also if I touch a phase/line cable where AC or DC is applied and I am in air will the current hit me and in what situation? Or if I am on the ground but with a STRONG ISULATOR which don't allow current to pass through my body to the ground. As far as I know the current always needs a return path and if lets say 300 kilovolts and 100 ampers of current is applied will it do me something if it cannot return anywhere? Even if I am in space (vacuum)? :)))))))) =) --Leonardo Da Vinci (talk) 11:11, 1 December 2010 (UTC)

Article talk pages are about improvements to the article. You can ask questions at the help desk. You may want to pick up a fundamental textbook on electricity in your primary language, a review of which would probably save you hours of typing questions here. --Wtshymanski (talk) 14:40, 1 December 2010 (UTC)

Variation of AC voltage with time

Although the voltage of a sinusoidal wave varies continuously with time, still we don't observe any change in the intensity of the visible light sources.Why? — Preceding unsigned comment added by 117.227.65.225 (talk) 17:53, 30 June 2012 (UTC)

Because most visible light sources operate at too high of a frequency. Even if the visible light were coherent, as in a visible light laser, the wavelength is much too small for the spatial variations of the voltage to be optically discerned (except with very specialized equipment). Also, please note the existence of periodic variable stars. It's not technically true that visible light sources don't vary in intensity, though at a macro-level, any correlation between intensity of fluctuations and ideal sinusoid AC waveforms tends to be rather weak.siNkarma86—Expert Sectioneer of Wikipedia
^{86 = 19+9+14 + karma = 19+9+14 + talk} 19:40, 7 April 2013 (UTC)

Electric and magnetic field time variation of an alternating current and the role of displacement current

It appears that little is said about the role of the E and B fields of alternating current in this article. Furthermore, analysis reveals that displacement current (based on time variations of the electric field) actually corresponds to the jerk (physics) of electrons (based on time variations of force on each electron, as determined by the time-varying electric field). If sin(x) is the velocity in arbitrary units, then -sin(x), the second time derivative of sin(x), is jerk in arbitrary units, given that we set t'=1. As it turns out, for an alternating current system, the derivative of velocity, cos(x), and the derivative of jerk, -cos(x), cancel out exactly, meaning that their variations compensate for each other directly. Displacement current and electron current can be seen as flowing in opposite directions at a given point in an alternating current system. Please advise on the possibility on incorporating source material regarding E, B, D, H, P, and M fields in alternating circuits. Sincerely, siNkarma86—Expert Sectioneer of Wikipedia
^{86 = 19+9+14 + karma = 19+9+14 + talk} 19:40, 7 April 2013 (UTC)

Current Flow

Commonname deals with article titles, not article content. And Charge is the term used when describing current, not current itself. --Kyohyi (talk) 17:05, 11 October 2013 (UTC)

Current is the term used when dealing with current.

Can you find one credible textbook for engineering applications of 3 phase AC (as described in the section you changed) that avoids using 'current' in this sense in favour of charge? Andy Dingley (talk) 17:23, 11 October 2013 (UTC)

Actually Charge is the term, it's in the definition. Using the term current to describe the term current is circular. Now I'm not dead set on the use of charge as a term, however I am against the use of the expression Current Flow. It's jargon and isn't defined in electrical texts. And the textbook that I have handy doesn't even describe 3 phase AC in terms of current, it defines it in terms of voltage and power. --Kyohyi (talk) 17:56, 11 October 2013 (UTC)

I don't care that you're against the term current flow. I care that many reliable sources do happily use it. Andy Dingley (talk) 18:11, 11 October 2013 (UTC)

Which would be perfectly fine if any of them defined it. --Kyohyi (talk) 18:14, 11 October 2013 (UTC)

This discussion seems to have started on Electric Current. I'd like to suggest that the discussion stay there until it is resolved.Constant314 (talk) 01:30, 15 October 2013 (UTC)

The Advantage of DC systems over the early AC systems needs citations

1. The use of batteries for backup and load leveling. This needs a citation showing that batteries were used for this purpose in the days of early AC systems.

2. Direct-current generators could be easily paralleled. I don’t dispute that, but I’ve seen a technician bring an AC generator on line. You had to know what you were doing, but it was not hard. He had a phase meters and volt meters and there were three light bulbs for backup. Actually, he used the three light bulbs and then fine adjusted with the meters. This needs a citation saying that AC generators are harder to parallel than DC generators. Maybe the governors on the prime movers then less steady.

3. AC systems used series circuits for lighting with the attendant problems. No dispute there, but a citation is needed saying that DC systems worked differently.Constant314 (talk) 23:19, 27 September 2014 (UTC)

Perhaps a reader could check out "Networks of Power" which goes into this at a little more depth, if this needs even more little blue numbers. One of the most exciting moments in commissioning a new hydroelectric plant generator is the first time it synchronizes to the grid - this is often a major milestone and may literally be a time to break out the champagne. --Wtshymanski (talk) 16:33, 28 September 2014 (UTC)