Talk:Three-phase electric power

message: I added a section outlining the balanced wye conneced and delta connected modes. The circuit diagrams with generator side offer more to the reader than the other two delta and wye diagrams.  
The voltage and current derivations add more to the story of where the VLL and VLN conversions come from than in the single phase load section. I would consider also consolidating the single phase load section moving its Unbalanced section as a second part to the balanced circuits.  — Preceding unsigned comment added by Jaredmporter (talk • contribs) 22:38, 27 November 2013 (UTC)
replies: text: Sounds like a good idea. Minor point is to be careful of the WP:TONE...just say what it is, rather than saying that "we see" it or that something is good to note. DMacks (talk) 23:00, 27 November 2013 (UTC)

text: That's a neat equation-alignment feature, no? DMacks (talk) 05:23, 2 December 2013 (UTC)
replies: text: yes, it is. 85.110.119.56 (talk) 06:03, 3 December 2013 (UTC)
thread_title:  Balanced Circuits 

message: Old discussions, some of which haven't been active in years, can be found in the talk page archives linked above. --Wtshymanski (talk) 00:40, 29 March 2014 (UTC)
thread_title: Archived

message: Can we clear this up?  It's not clear why my edit was reverted.  To my knowledge, the standard electrical install required for most home-loan financing is a 200-A 2-phase system.  There are other details if you look farther up the distribution network but at a residence, there are 2 phases and a neutral.  So... what's the reason for the reversion?  — Preceding unsigned comment added by Neffk (talk • contribs) 19:41, 5 May 2014 (UTC)
replies: text: It's fed from one of the three phases of the distribution, which is converted to a split-phase. The result is two opposing phases (180°, or + vs – of same "phase"), not two of the three three-phase (120°) phases. :File:Polemount-singlephase-closeup.jpg is pretty standard last hop before residence. Notice one primary-side bushing, and two secondary (plus center-tap neutral). DMacks (talk) 19:57, 5 May 2014 (UTC)

text: The standard supply to an American home is 3-wire single-phase.  It's not clear what the reference to 200A for home financing is referring to though.  There are thousands of homes across the U.S. still running on 100A (or lower) services, and that really has nothing to do with financing.  Some financers might balk at specific types of equipment which have been shown to have problems (e.g. some Federal Pacific panels), but that's a different matter. 97.84.107.236 (talk) 16:08, 23 November 2015 (UTC)
thread_title:  Revision as of 12:58, 27 March 2014 

message: Hello. This article and three phase are about exactly the same topic. Three phase explains the mathematics of a three phase system, but I think than that should be explained here as well, since it's a single topic. Under the relevant policy on merging I think that this is an instance of overlap. I can understand having several articles on a topic when it's very lengthy and complex, like relativity (physics) and introduction to special relativity but this is not the case here. Regards. QrTTf7fH (talk) 16:10, 4 August 2014 (UTC)
replies: text: Go for it. Once you eliminate the math typesetting from three phase, there's not much content that isn't duplicated here or better off here. Wikipedia is not a textbook and showing all the derivations is a job for a textbook, not an encyclopedia. --Wtshymanski (talk) 02:50, 5 August 2014 (UTC)

text: Oppose  This merger proposal has been up since August of 2014, and though there has been little discussion here, it is obvious that there is no consensus.  My personal opinion is that Three Phase should be its own article, as it is its own mathematical and physical concept and deserves its own discussion.  Meanwhile, the three-phase electric power article also should be its own article, as it is the most widely used form of electricity distribution in the world.  Since this proposal has been up for a very long time, and there is not consensus, and it has been sparsely discussed for several months, I think this fits the description of a failed merger proposal (see Step 4 on that page), so I'm removing the merger tag from the article.  If anyone strongly disagrees, please start a new discussion!  Spiral5800 (talk) 17:34, 23 June 2015 (UTC)
thread_title:  Merge 

message: Suggest the reference to IEC 60446 is cleared and the correct reference to IEC 60445 is put in (change since 2010), this is regarding color coding of wires
Sigurdurs (talk) 09:27, 29 April 2015 (UTC)
replies: text: Done, but I have left the link to 60446 in place since that page has the information.  IEC 60445 is currently just a redirect to List of IEC standards. SpinningSpark 15:44, 29 April 2015 (UTC)
thread_title:  Semi-protected edit request on 29 April 2015 

message: There is a comparison of three phase delta with one phase, hot and neutral, in power transmission efficiency.  It would seem more fair to compare to two-wire single phase with grounded center tap. Also, is phase-to-phase voltage a more useful comparison than phase-to-ground? Gah4 (talk) 21:00, 13 May 2015 (UTC)
replies: text: I don't understand why you want to compare to the rather unusual single-phase centre-tapped (split phase).  The comparison between single-phase two-wire and three-phase three-wire on a power per conductor basis seems perfectly valid to me.  On the phase-phase voltage issue, the limiting factor on overhead lines is likely the voltage across the insulators between the lines and the pylon, that is, the phase to earth voltage.  The phase to phase voltage may be significant in an underground cable however.  In any case, my purpose in the edit under discussion was simply to restore a reference which properly verifies the text in the article, not to try and justify the validity of the comparison.  If you want to make a different comparison, you are welcome to look for a source that it can be cited to. SpinningSpark 22:18, 13 May 2015 (UTC)

text: To be sure that my comment wasn't confusing, I said two-wire with grounded center tap. If you want to minimize phase to ground voltage and maximize phase to phase voltage, you have to ground the center tap of single phase and three phase. Not allowing for the optimal system for both cases is pretty much the same as the old 'one hand tied behind your back' restriction. Gah4 (talk) 07:20, 11 December 2015 (UTC)
thread_title:  Fair comparison 

message: I chose to add some extra information about high phase order systems dealing with the pros and cons of why they could be practical but aren’t. In addition, I wanted to make it clear that while 6 or 12 phase systems are indeed more efficient, there are clear drawbacks that make it impractical today. If accepted, this should go in the last bullet point under 'Alternatives to three-phase'.
Please change 
Bulletpoint under 'Alternative to three-phase' should change from:
	•      High-phase-order systems for power transmission have been built and tested. Such transmission lines typically would use six phases or twelve phases. High-phase-order transmission lines allow transfer of slightly less than proportionately higher power through a given volume without the expense of a high-voltage direct current (HVDC) converter at each end of the line. However, they require correspondingly more pieces of equipment.
to the following:
	•	High-phase-order systems for power transmission have been built and tested. Such transmission lines typically would use six phases or twelve phases in order to maintain both the cancellation of triplen harmonics and forgoing the need for a neutral wire for return. Higher-phase-order systems provide more efficiency and smoother power transfer. High-phase-order transmission lines allow transfer of slightly less than proportionately higher power through a given volume without the expense of a high-voltage direct current (HVDC) converter at each end of the line. However, with these benefits come issues of cost, equipment, and analysis. Higher phases require an increased number of buses and conductors, in addition to to more power transmission lines. These lines also need to be transposed significantly with one another-for example, a six phase power system would need to transpose the line a total of six times to maintain balance. Analyzing a system with higher phase is also much more complex than a three phase network; therefore, maintenance of a higher order system is more difficult to comprehend. Additionally, the increase in efficiency of one phase to three phase power is much more significant than the increase in efficiency of three phase to a higher phase; as a result, it is at three phase power that we find the optimal amount of power efficiency for cost. It is also important to note that there are little to no advantages for a four or five phase power system compared to a three phase system as these systems are unable to deliver constant power; therefore, only higher order n-phase systems that are multiples of three should be considered as being advantageous to the conventional three phase system. 
Sidd26 (talk) 21:39, 9 December 2015 (UTC)
replies: text: A center-tapped one phase system isn't called two-phase even though the phases are 180 degrees apart. This makes sense. So, what is a six-phase system? Is it a three-phase system, adding lines 180 degrees from each phase? Seems like according to the counting system, that is still three phase. It may, however, in some cases be useful, and is easily to interface with three-phase systems. So, six phase should be 12 wires, and 12 phase should be 24 wires. These won't be easy to interface with the rest of the grid, and are unnecessarily complicated. Gah4 (talk) 07:41, 11 December 2015 (UTC)
thread_title:  Semi-protected edit request on 9 December 2015 

message: Unbalanced loads
When the currents on the three live wires of a three-phase system are not equal or are not at an exact 120° phase angle, the power loss is greater than for a perfectly balanced system. Current unbalance can be caused by a number of things. One possible instance is unequal distribution of a single-phase load, which can occur if low voltage single-phase services are connected to the phase closest to neutral. Current unbalance is the primary cause of voltage unbalance, which increases heating losses in three-phase motors and negatively affects the torque and speed of the motor. The method of symmetrical components is used to analyze unbalanced systems.
Wye
For the wye case, all loads see their respective line voltages, and so:[12]
 
 
 
where Ztotal is the sum of line and load impedances (Ztotal = ZLN + ZY), and θ is the phase of the total impedance (Ztotal).
The phase angle difference between voltage and current of each phase is not necessarily 0 and is dependent on the type of load impedance, Zy. Inductive and capacitive loads will cause current to either lag or lead the voltage. However, the relative phase angle between each pair of lines (1 to 2, 2 to 3,and 3 to 1) will still be −120°. In a wye connection, the phase voltages are equal to the line-to-neutral voltages (Va, Vb, Vc) and the phase currents are equal to the line currents (Ia, Ib, Ic). 
The wye connection can be analyzed through a one-line diagram. By applying Kirchhoff's current law (KCL) to the neutral node, the three phase currents sum to the total current in the neutral line. In the balanced case:
 
And in the one-line diagram: 
Ia = Va / ( Zline + ZY) , Ib = Vb / ( Zline + ZY) , and Ic = Vc / ( Zline + ZY)
Delta
In the delta circuit, loads are connected across the lines, and so loads see line-to-line voltages:[12]
 
Further:
 
 
 
where θ is the phase of delta impedance (ZΔ).
Relative angles are preserved, so I31 lags I23 lags I12 by 120°. Calculating line currents by using KCL at each delta node gives:
 
and similarly for each other line:
 
 
where, again, θ is the phase of delta impedance (ZΔ).
In a delta connection, phase voltages are equal to the line voltages (Vab, Vbc, Vca) and the phase currents are equal to the current line to line (Iab, Ibc, Ica). Neutral is not present in a delta connection. 
Jgeffrey (talk) 21:49, 9 December 2015 (UTC)
thread_title:  Semi-protected edit request on 9 December 2015 

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thread_title:  External links modified 

message: I put a  in for staggering the phases in Germany, and that the first phase has more load.  I suppose it makes some sense, but still isn't so obvious.   Panels I know of cycle the phases going down, and I don't see so much reason to put a higher load in the first, fourth, seventh, etc, positions. Enquiring minds want to know.  Gah4 (talk) 23:58, 27 September 2016 (UTC)
thread_title:  Phase one 

message: I propose that Phase sequence be merged into Three-phase electric power, because the section Three-phase_electric_power#Color_codes in effect discusses sequence. Comfr (talk) 19:02, 14 October 2016 (UTC)
replies: text: And then redirect to that section.  Sounds right to me.  Why does Phase sequence exist at all? Gah4 (talk) 20:25, 14 October 2016 (UTC)
replies: text:  I put in a redirect at Phase sequence but on re-reading the section here, there was no need to merge in that text - it's lucidly described here and with a reason why it matters. --Wtshymanski (talk) 17:10, 17 January 2017 (UTC)
thread_title: Merge proposal

message: I don't like this article. I don't think it's well written. It's rather sloppy, unorganized and I think it should be revised. In particular, I don't like the way it's split into sections. I have a series of comments.ICE77 (talk) 04:33, 6 November 2016 (UTC)
replies: text: Well, it can go up and down along the whole path, depending on the optimal voltage for each segment. I suppose in most cases, it it stepped on once, right at the source, and then down in steps, closer and closer to the end user. But that is already more than just  stepped up for transmission and then stepped down for local distribution Gah4 (talk) 05:23, 6 November 2016 (UTC)

text: Many articles have duplication. Sometimes it is useful, as someone might not read the whole article. Most often, it can probably be fixed. Sometimes it comes from article merging. Gah4 (talk) 05:23, 6 November 2016 (UTC)

text: As well as I know, many places in Europe distribute three phase to houses. Not so unusual in industrial buildings, even apartments and dormitories in the US, but pretty much never to single family houses.  Gah4 (talk) 05:23, 6 November 2016 (UTC)

text: If you see an individual sentence that needs fixing, just fix it.  Others will change it again, if needed.  For bigger changes, discussing it here is probably best. Gah4 (talk) 05:23, 6 November 2016 (UTC)

text: New work is in new buildings, old work is in existing buildings.  Yes, that confused me for a while. Gah4 (talk) 05:23, 6 November 2016 (UTC)
replies: text: "The three-phase system was independently invented by.... " looking up citations on this in the past what I came across is none of these people invented "three-phase", it was an obvious idea right from the start of engineering AC systems. That is why these (kinda WP:SYNTH) lists change through Wikipedia - they really only cite the people who worked with it, not who invented it... and that is quite a few engineers. Another citation notes three-phase was a great idea but a logistical nightmare, hard to implement in all the single phase systems and even DC systems that existed at the time. It was a slow roll out patched over by a "Universal System". Noticed it needed rewriting for a while. Fountains of Bryn Mawr (talk) 13:48, 6 November 2016 (UTC)
replies: text: Was it really that obvious? It is hard to know now what people knew or thought at the time. It is pretty obvious when the idea of an AC induction motor comes up, but I am not sure that was so obvious at the time.  I thought that two-phase (four wire) systems were built in the early AC years, before three-phase was obvious enough better, but I haven't tried to follow it so carefully.  Was the original Niagra falls system two or three phase? Gah4 (talk) 20:30, 6 November 2016 (UTC)
replies: text: Now you will have me hunting for references ;). "obvious" as in all the early thinkers in AC (Haselwander, Ferraris, Dolivo-Dobrovolsky, Wenström, Tesla) were on to it. 3-phase was out there before Niagara, Dolivo-Dobrovolsky perfected that in 1889, but  Niagara was built by Westinghouse and they had 2-phase based Tesla patents (a second contract went to GE to build 3-phase transmission lines). The better European 3-phase systems were being kept out of America at that point by the Tesla patents (the same thing would happen again a few years latter when the Wright Brothers patents would keep European aircraft innovations out of America). At the point of Niagara it was all academia, the systems they were linking up were archaic single phase AC, DC light, DC street cars, and factories powered by DC motors or steam engines -- 2-phase or 3-phase didn't matter...  the advantages of either system were a pipe dream. Fountains of Bryn Mawr (talk) 23:27, 6 November 2016 (UTC)
replies: text:  I've had a look at a few of the points made above. Main articles are for details, we just need to summarize here and link. People should come back the next day and read their contributions out loud to themselves - it would smooth our our style a lot. --Wtshymanski (talk) 18:30, 17 January 2017 (UTC)
thread_title:  Comments on the article 

message: In the US, you pretty much never see three phase in single family homes.  It isn't so unusual for apartments or dormitories, though.  But as I understand, it is usual in some countries in Europe, and maybe elsewhere. Are there any sources on which countries? Gah4 (talk) 22:44, 10 November 2016 (UTC)
replies: text: My experience in Australia is vaguely relevant. My family lived in a house that, like most others, was served by a single phase. Then my mother bought a new oven that operated on the higher voltage only available with two phases. The oven was installed and the second phase was brought to the house and everyone lived happily ever after. Dolphin (t) 11:00, 11 November 2016 (UTC)
thread_title:  Single family homes 

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thread_title:  External links modified 

message: point 5.2.3 L1 -> black, L2 - brown, L3 -> grey  — Preceding unsigned comment added by 188.84.191.124 (talk) 12:18, 31 December 2017 (UTC)
thread_title: AC color IEC 60446

message: Voltage is induced in the secondary (right coil) only when the voltage is changing in the primary  Seems to me that from the way the law of induction works, a voltage is generated by a change in current. Though the current has to change appropriately to induce the right voltage. Gah4 (talk) 19:53, 27 April 2018 (UTC)
replies: text: In the context of 3-phase power, the statement is probably acceptable as is.Constant314 (talk) 20:11, 27 April 2018 (UTC)
thread_title:  ''Voltage is induced in the secondary (right coil) only when the voltage is changing in the primary'' 

message: That is, 2\sin(°).   It is well known that for symmetric three-phase that the line to line voltage is sqrt(3) times the line to neutral voltage.  There are plenty of sqrt(3) in ratios for equilateral triangles, so that shouldn't be too surprising. The actual form that it comes out is 2\sin(°) which comes from a difference of two sines identity. Gah4 (talk) 05:39, 6 August 2018 (UTC)
replies: text: I've been watching this discussion.  I have to agree that trig function is just sort of tossed out there like an Easter egg, but so is the sqrt(3).  You are allowed to make statements in the lead without citations if they are supported in the body of the article.  I think the equations down the Delta section justify both, but they seem to have jumped from a trig like expression to a factor of sqrt(3) by skipping a step.  I think that probably you can add the missing step and then you will have justification for your trig identity and the sqrt(3)
Here are the equations
\begin{align}
V_{12} &= V_1 - V_2 = (V_\text{LN}\angle 0^\circ) - (V_\text{LN}\angle {-120}^\circ) \\
       &= \sqrt{3}V_\text{LN}\angle 30^\circ = \sqrt{3}V_{1}\angle (\phi_{V_1} + 30^\circ), \\
\end{align}
You and I know that sqrt(3) came from a trig expression, but it may not be obvious to others. Constant314 (talk) 07:46, 6 August 2018 (UTC)

text: I would have made it: \begin{align}
V_{12} &= V_1 - V_2 = (V_\text{LN}\angle 120^\circ) - (V_\text{LN}\angle {0}^\circ) \\
       &= \sqrt{3}V_\text{LN}\angle 60^\circ = \sqrt{3}V_{1}\angle (\phi_{V_1} + 60^\circ), \\
\end{align}
I was going to say that yours was wrong, but then I saw the minus sign. I think that makes it -60 degrees, though. 
The identity is sin(A)-sin(B)=2*cos((A+B)/2)*sin((A-B)/2) Gah4 (talk) 04:41, 12 August 2018 (UTC)
thread_title:  ''That is, <math>2\sin</math>({{formatnum:60}}°)'' 

message: In the above section there is discussion on phase order, and how people get it right. It seems that there are tools, some simple, some complicated and expensive, to indicate phase, such as these. The page indicates a simple one with a capacitor, two neon lamps and current limiting resistors.  Seem more obvious than spending hundreds of dollars for one. It does seem that black-red-blue is popular, but do any sites, such as NEMA, mention this?  As above, the only thing that UL says, specifically about pump motors, is not white, gray, or green. It seems that a popular way to start a large (maybe 10HP) motor is first as wye, then as delta. But once you get one right, the other will also be right. Gah4 (talk) 22:42, 16 August 2020 (UTC)
replies: text: Added a bit on tools used for testing and why one would want to test. --Wtshymanski (talk) 19:51, 18 August 2020 (UTC)
thread_title:  phase indicator 

message: Greetings,
This page could be more informative for electrical power systems engineering and research if it included sequence impedance as in symmetrical components impedance and DQO (Direct Quadrature and Zero) impedance. Most of the power systems protection engineering is done with positive, negative and zero sequence impedances these days. DQ impedances are also used for modeling, drives controls analysis, and stability analysis of power electronic systems. If you argue that these impedances should be under DQ0 transform or Fortesque transform it would be like saying that impedance belongs under complex numbers or the Fourier transform, since that is the mathematical origin. I think these impedances belong on this page because it covers the use cases of electrical impedance in its various forms. 
thank you. 173.66.144.197 (talk) 02:14, 29 March 2024 (UTC)
replies: text: The problem is that Wikipedia is not a textbook of electrical engineering.  Wikipedia is supposed to be a general reference encyclopedia.  If you've observed the *considerable* difficulty that our process has in producing a lucid correct explanation intelligible to a general reader who does not have 30 years in the electrical business, perhaps you too share my despair at the idea of trying to explain all this here.  Best bet is to point at your favorite textbook and let the pros handle it.  We're all just dilettantes, hobbyists and fanbois here; we can't be trusted. Anyone relying on Wikipedia for research should be fired.  --Wtshymanski (talk) 03:48, 8 April 2024 (UTC)
thread_title:  Sequence Impedance and DQO impedance