Talk:Synchronous motor

Jargon, undefined concepts, need for linking to other WP pages to guide the clueless
I have a basic, college-physics plus new-to-electronics-as-hobby level background understanding of motors, and can throw together a basic DC motor out of office supplies to amuse children and small animals. I even have a doctorate, post-doc, and most of a second doctorate in reasonably demanding scientific and technical disciplines. In spite of what might be a slightly above average WP reader background and vocabulary, this article has jargon that rivals the impenetrable WP articles done by scholarly mathematicians.

There are more multiple adjective noun phrases than an episode of Star Trek!

E.g. ''...as a result, provides the second synchronized rotating magnet field  of any AC motor. A synchronous motor is only considered doubly fed if is supplied with  independently excited multiphase AC electromagnets on both the rotor and stator.''

Please consider the following suggestions to humanely supply your dear readers with your knowledge and expertise:
 * Define technical, novel or complex concepts. You can do this simply via parenthesis or footnotes or a definition section or side box.  While links to other WP pages should be liberal, you should not have to open a dozen pages just to get through the introduction.
 * A simple, in-line definition can go a long way to improve readability. You may need to have more precise or detailed definitions in preceding text as a separate sentence, or as footnote, link, etc.
 * Resist urges to dumb-down. Bring your readers up to speed.  Assume they are eager to learn, but may not have arrived at your page via all the other pages needed to comprehend.
 * Be generous in linking to other relevant WP pages and external sources. Make an effort to search for relevant pages.
 * When I am writing in my own domain, I box-quote key concepts, technical terms and phrases, and synonyms for key concepts and phrases. Sure, a bunch show up in red, but even those help you.
 * Maybe all is needed is a redirect page to point to an article (or section of article)--if you were looking for something via a specific term, chances are others would as well.
 * Sometimes, fairly often in fact, you just need to add the right WP page name (after you find it) to whatever term you use.
 * It varies dramatically by discipline, but as many WP pages there are, there are still important gaps, so you might need to create a new page. Even a bare-bones, "let's start a new page" article, with a brief introduction (so the WP bots/über-editors don't killthe page in its infancy like so many cats) and a link to reasonable web site or publication is helpful.   Enlist he enthusiastic support from contributors on talk pages of other articles.
 * Complex topics, esp. those using multiple adjectives, adverbs, and nouns together as a single concept pose special challenges for linking. Different WP articles may be needed, often with overlapping use of words in your otherwise brilliant and well written article.  (It is, I just cannot understand it.).   — Preceding unsigned comment added by 75.73.1.89 (talk) 18:53, 29 September 2016 (UTC)

Torque angle
I'm not sure about others, but personally I feel that the most important aspect of how a synchronous machine works, is absolutely left out of this article. It's even emphasized that no slip is needed to produce torque (as in contrast to asynchronous machines, where a rotation speed difference is required to produce torque), but after that there is no mention of how torque is actually produced in a synchronous machine! The rotor has to be lagging behind the rotating magnetic field of the stator(but having the same rotational frequency), and THIS creates a force. If in generator mode (and locked to the grid), the rotor is leading, followed by the rotating magnetic field of the stator. —Preceding unsigned comment added by 89.132.129.41 (talk) 12:12, 27 December 2010 (UTC)

I agree discussing torque angle is important. This leads to an explanation of the maximum torque before skipping, for instance. There are also important oscillations that can occur in the torque angle when the motor is perturbed. --AJim (talk) 06:27, 21 December 2012 (UTC)


 * Think of a synchronous motor as always being at the same speed as the line voltage generators, however the phase angle difference of its acting as a counter-generator depends on the load. The higher the difference in phase, the higher also the current and torque. 70.27.152.243 (talk) 20:58, 20 July 2016 (UTC)

Request for expansion

 * I'd like to see more information on the control of a synchronous motor/generator. What's the amount of current you'd like to send through the powering magnets, how do you calculate it?
 * There are many ways a synchronous motor can be constructed, an explanation with pictures will be useful.
 * How do you start it? It can't be just turned on. It has to be either brought up to speed, and then the power can be turned on, or it has to be controlled using power electronics which control the frequency. Or alternatively one could start without current through the rotor, and use an impedance instead, it would be a regular AC motor, and then switch to synchronous when it's brought up to speed. If someone could elaborate on this subject, please add it to the article. —Preceding unsigned comment added by Aphexer (talk • contribs) 09:11, 12 January 2008 (UTC)

Content removed
I removed the following "disadvantages" section. The points made are only valid for specific variants and are not otherwise generally applicable.

A different section should be started to discuss due to their peculiarities.
 * high power synchronous motors
 * synchronous condensers

Disadvantages

 * They are fundamentally much more expensive than their squirrel cage counterpart due to their particular construction.
 * A synchronizing equipment must be installed in order to apply current to the rotor windings when the motor achieves 95-97% of its synchronous speed.
 * They are often used in high-power applications (above 1 000 HP), when proper starting techniques must be used in order to minimize the undesirable effects on the electric network due to the large amount of current required. This is not unique to synchronous machines, though, as any motor will draw 5 to 6 times their nominal current during the starting phase.

Choppingmall 00:07, 25 August 2007 (UTC)

I also removed the following:

Construction
The stator of a synchronous motor is not different from a squirrel cage motor, as it is composed of windings disposed to provide a rotating magnetic field when alternating current is applied. The rotor, though, is designed to provide a static field by itself to lock with the stator's. This is obtained with a permanent magnet in the case of small motors and DC windings on bigger units. A small generator, called an exciter, is sometimes mounted on the shaft of high power motors in order to provide 3-phase current, which is rectified and fed in the motor rotor windings.

The principle of having the rotor provide a static field (generated by windings or permanent magnet) which "locks" with the stator's is a really good description -- but the rest is not generally applicable. A section should probably be made to describe "typical" construction, but acknowledge that there are other ways of doing it. Remember that high power synchronous motors are relatively unusual compared to small ones, so don't generalize based on their characteristics.

Choppingmall 00:26, 25 August 2007 (UTC)


 * Yeah, the removed content probably were not perfect, but current version does not have ANYTHING about construction, so this is worse. This indeed is insufficient, but it is better than nothing. I will restore section about construction in few months, if no one objects. -Yyy (talk) 16:56, 14 December 2008 (UTC)

Spam
A link to electojects.com has been repeatedly added to Stepper motor, Electric motor and Brushless DC electric motor by Special:Contributions/217.53.109.235, Special:Contributions/82.201.156.201, Special:Contributions/217.53.107.168, Special:Contributions/217.53.16.164, and others.

The link in question is registered to Abdoh Ali Mohamed, Hay Swesri, Nasr City, Cairo, Egypt.

I wonder if the four IP addresses listed above have any connection... Naw, couldn't be. Egypt is a big country. Must be a coincidence.

I'm going to start patrolling wikipedia for any links to electojects.com or redirects to it and deleting them on sight. If they come back, I'll move to blacklist the address. Mdsummermsw (talk) 18:20, 28 December 2007 (UTC)

Poor illustration
I know we can only use pictures taken of the hardware we have around our houses, but could we please get a picture of a "synchronous motor" that isn't part of a floppy disk drive? A titchy brushless DC motor is not what most books call a synchronous motor. Encyclopedia illustrations should be generalized and typical of the subject, and not require a page of explanation on how this special case is really an instance of the general concept of "synchronous machines". I'd like a reference that actually calls the spindle motor in an FDD a "synchronous" motor. --Wtshymanski (talk) 14:00, 26 March 2012 (UTC)


 * AFAIK, there is little in common with a floppy motor and a BLDC. Their inverters assume a low, fairly constant load and simply drive the motors with a fixed-frequency AC inverter. They don't do any of the complexity associated with a BLDC and disk speed control is just as a simple synchronous motor.
 * OTOH, the masthead image here is a great big AC-DC rotary converter from a couple of centuries ago. That's hardly representative either, of either motors or typical synchronous (i.e. non-slipping) motors. I have some cam timers here, but their motors just look like plastic blocks and I'm not inclined to bandsaw one in half just for a photo.
 * Talking of misleading, what do you reckon to recent changes to BLDC and the new motor constants article? I think this notion of Kv could revolutionise brush-commutated motors... Andy Dingley (talk) 14:24, 26 March 2012 (UTC)
 * I photographed a motor from a Teletype machine and put it on the page. It looks like a motor, although a rather old style one. That's a single-phase 1/40HP 1800 RPM synchronous motor, with a centrifugal switch to start it as an induction motor.  Single-phase medium sized synchronous motors without electronic controls are not that common today - there's not much between clock size and big three-phase industrial motors. --John Nagle (talk) 07:45, 4 January 2014 (UTC)

Unsourced Material
Article has been tagged for needing sources since March. Feel free to re-add below material with appropriate references. Doniago (talk) 14:44, 14 December 2012 (UTC)
 * Is there anything the least bit controversial or dubious about all this? If it really pains you ,put in . --Wtshymanski (talk) 21:16, 14 December 2012 (UTC)
 * If that's the best you can do for a reliable source, the information doesn't merit inclusion in any case. Is there anything so challenging about being asked to provide a specific source, or do you simply not want to do the work that policy requires once information has been challenged? Doniago (talk) 21:43, 14 December 2012 (UTC)


 * Wikipedia guidelines allow the inclusion of uncited material that is unlikely to be challenged (WP:BLUE). The problem here is that someone has challenged the material and it thus requires a verifiable reference (WP:RS).  The bigger problem is that Doniago is almost as much of a tendentious editor as you are.  He has made it his mission to demand citations for the most blazingly obvious claims throughout Wikipedia no matter how obvious or accepted by concensus they may be.  A quick look at his contributions(??) history shows that he is still tagging dozens of previously unchallenged claims at a sitting.  In this case, though, we are discussing technical details which may be obvious to you and I, but nevertheless still require appropriate references to remain in the article.  Your comment though steeped in sarcasm is not an acceptable reference as I cannot find a work with the title given (an author or ISBN might have helped).  I B Wright (talk) 15:22, 15 December 2012 (UTC)
 * Well, I suppose I should thank you for your support in this matter. So, thanks for your support in this matter. Doniago (talk) 13:49, 17 December 2012 (UTC)
 * I can't see where D has challenged the material - in the sense of asserting any inaccuracies, etc> all D has done is remove it, no? William M. Connolley (talk) 13:53, 17 December 2012 (UTC)
 * Additional discussion here at EAR. JohnInDC (talk) 15:11, 17 December 2012 (UTC)
 * I'd add that I don't think that simply tagging material as unsourced and then removing it because it remains unsourced can fairly be called a challenge. Or stated more precisely, it's a procedural challenge, not a substantive one.  And the whole point of WP:BLUE is that sometimes we should restrain our more pedantic impulses, i.e., procedure trumping substance.  JohnInDC (talk) 15:26, 17 December 2012 (UTC)
 * WP:BLUE is an essay, not a policy or guideline. It may not even represent a majority opinion. Of course, there's also WP:NOTBLUE. WP:MINREF explicitly lists the removal of material as a challenge. For that matter, it also lists tagging as a challenge. WP:BURDEN expressly states that material that has been removed due to sourcing concerns should be addressed by providing an inline citation when re-adding said material. Doniago (talk) 16:41, 17 December 2012 (UTC)
 * Yes. I understand the policies.  I understand that removing this material is defensible under them, even "correct".  My point is that the blind and indiscriminate application of rules can be more destructive than the ills the policies are designed to guard against.  I'd really be interested to understand how removing this material is better for the project than leaving it in, even tagged as it is.  JohnInDC (talk) 16:58, 17 December 2012 (UTC)
 * Leaving the information in the article for over six months led to no improvement. Why should I accept that leaving it as-is for a longer time will lead to any improvement? At what point do you think it's appropriate to address unsourced material via removal? Never? Hell, if nothing else my removing the material brought attention to the problem.
 * Look, I'm not trying to cause problems here, but the reality is that attention was called to the sourcing issues with the article over six months ago, and nothing's been done, at least with regards to the sections noted below. In fact, one of the editors who fought me on the removal claimed that there are a lot of inaccuracies in the article, but apparently hasn't done anything about those either. I don't see a way to root those out without references to work with.
 * If one or more editors want some time to provide sources, I'm happy to leave the article alone with the understanding that it will be improved and some idea as to when that will happen. Perhaps one of the "under construction" templates can be invoked. If editors aren't willing to take action beyond reverting me every time I remove the material, which policy and other editors support (see above, see the discussion at EAR, see the recent ANI discussion Wikipedia:Administrators' noticeboard/Incidents), then I'd very much like to hear what they recommend as an alternative approach. Doniago (talk) 17:12, 17 December 2012 (UTC)
 * So, you have absolutely no comments at all on the actual material. You don't know if its good or bad, because you don't understand it. Well, fine. You've called this to the attention of other folks, your task is done, you can happily de-watchlist this page and be on your way William M. Connolley (talk) 17:18, 17 December 2012 (UTC)
 * Speaking for myself, I am content to leave material in articles, even if it's tagged for sourcing issues, if I don't know anything about the subject matter area, the material appears to not to be contentious, and editors who do know something about the area seem content to leave the material undisturbed, without the sources. It's a judgment call, to be sure, but Rules don't always cover every situation in the best way every time.  JohnInDC (talk) 17:31, 17 December 2012 (UTC)

RFC on unsourced material in previously-tagged article
I am opening an RFC to discuss the issue noted above; specifically whether it is best to leave unsourced material in an article that has already been tagged for this problem for over six months, or whether there are other options that should be considered/exercised. Doniago (talk) 18:03, 17 December 2012 (UTC)


 * Yes, another option is to search for sources yourself, which will rapidly confirm the material to be uncontroversial.  Spinning Spark  18:33, 17 December 2012 (UTC)
 * And you could presumably do the same. Doniago (talk) 19:29, 17 December 2012 (UTC)
 * You're somebody. Be Bold - you can add refs as well as tags. --Wtshymanski (talk) 19:56, 17 December 2012 (UTC)
 * If I had refs and the time to add them and cared enough to do so, I would. And I already was BOLD. Some editors didn't care for my approach to resolving the problem, so here we are. Doniago (talk) 19:58, 17 December 2012 (UTC)
 * Not so much WP:BOLD, far nearer to a WP:SPIDER; burning down the village to save it, kind of deal. FWIW I actually very recently needed and read the information you deleted, and I found the information credible and informative and dovetailed very well into what I knew, so I'm not looking on you at all positively.Teapeat (talk) 20:58, 17 December 2012 (UTC)
 * It's interesting that you found the article credible, since not coming from an electrical engineering background I do not have that luxury. That is part of the deal with sourcing on Wikipedia, so that readers can be certain of its credibility. Betty Logan (talk) 21:08, 17 December 2012 (UTC)
 * Adding a little number to the end of a piece does not make you certain of its credibility if you are not confident you can understand the source. You will still need an electrical engineer to read the source and tell you the article is in accordance with it.  Yet you have several EEs on this page telling you that the material is fine and that there are numerous elementary textbooks confirming it.  Spinning  Spark  21:28, 17 December 2012 (UTC)
 * If there is such an abundance of sources available, why are the people who are so certain of the unsourced material's credibility so focused on debating the material's removal rather than taking the less contentious and more productive approach of adding appropriate citations? Doniago (talk) 13:45, 18 December 2012 (UTC)
 * Probably mostly because people have studied this matter in some way or know it by experience, and know it as largely established, but they do not know references that would reach the acceptable standards to cite it. (Just try to find a reference on the fact that most people living here were born on earth, just to see. -- 213.189.160.119 (talk) 12:21, 28 December 2012 (UTC)


 * Comment My personal approach on "start" class articles is that basic development is preferable to strict adherence to the policy, so I probably wouldn't have removed the content myself. That said, this is a technical article that any reader without an advanced engineering education is unlikely to know is correct or not. I don't see how from a policy point of view you can prevent an editor removing unsourced content if no-one is willing to reference it. Betty Logan (talk) 21:08, 17 December 2012 (UTC)
 * We can't expect stub/start class articles to be referenced very well at all, so deleting unreferenced material in the absence of being fairly sure it's wrong is usually unreasonable behaviour. Otherwise we could delete most of the material from start class articles out of hand.Teapeat (talk) 22:31, 17 December 2012 (UTC)
 * It's common sense so I've tried adding that to the policy, as sensibly as I could put it.Teapeat (talk) 22:31, 17 December 2012 (UTC)
 * Apparently it is not in fact common sense, given that your policy modification was reverted shortly after you inserted it with a recommendation that you discuss it at the pertinent Talk page. Similarly, SpinningSpark's attempts to revise policy have been heavily contested. Doniago (talk) 13:45, 18 December 2012 (UTC)
 * You don't know if any Wikipedia article is correct or not, regardless of the number of footnotes in it. By the time you check out the offered references and can decide "This one is credible, this one is sketchy, and this one is deep in the fringes", you've become an expert in the field and no longer need the Wikipedia article at all. --Wtshymanski (talk) 21:14, 17 December 2012 (UTC)
 * By that argument, why provide sources for anything at all? It sounds like you are more concerned with the policy itself in that case. Doniago (talk) 13:45, 18 December 2012 (UTC)
 * Regarding policy, the relevant part of WP:V says "When tagging or removing material on these grounds, make it clear that you have a concern that the material itself is unverifiable. If instead you think the material is verifiable, it is better to try to provide an inline citation yourself before considering whether to remove or tag it."  Spinning Spark  21:32, 17 December 2012 (UTC)
 * At the time the article was tagged for needing sources that phrasing was not a part of WP:V, I believe. The template itself says that unsourced information may be removed, as it ultimately was (to here, not an outright deletion). The removal itself was in accordance with the template- editors had over six months to provide sources and failed to do so, so the information was removed as a legitimate challenge, on top of the legitimate challenge already established by the template. If the information is to be reinserted, then per WP:BURDEN it is incumbent on the editor adding it to provide citations. Doniago (talk) 13:45, 18 December 2012 (UTC)
 * Before the current phrasing we had "It has always been good practice to try to find and cite supporting sources yourself" which is pretty much going in the same direction. I don't care what the templates say, they are not themselves policy, although they should be trying to reflect it.  Spinning  Spark  17:28, 18 December 2012 (UTC)


 * editors didn't care for my approach to resolving the problem, so here we are rather says it all - you don't like the answer you've got, so you'll try asking the same question in a not-really-different way, in a rather transparent attempt to get a different answer 21:42, 17 December 2012 (UTC) — Preceding unsigned comment added by William M. Connolley (talk • contribs)

Tell you what Doniago, show us that you really want to improve this article rather than just mechanically delete things. Make a list, as long as you like, of all the facts you think need citing. Please, do not just simply reply it all needs citing. What I am looking for is a list of single sentence, testable facts I can investigate with a simple true/untrue result. For every item on the list I will provide you with a link to a page in a reliable source verifying it. You will format the citations and put them in the article. Anything I fail to confirm within a week you can delete.  Spinning Spark  16:45, 18 December 2012 (UTC)
 * My list is provided above this RFC, though there is likely other information within the article that ideally should be cited...for reasons that are hopefully obvious, right now I'm disinclined to go looking. The list would be a good start though. If there are alleged facts contained there that you believe are "obvious" enough that we should be able to waive citing them, please let me know and I'll be happy to offer an opinion. Obviously I can't represent all editors, but I can certainly offer my two cents. Doniago (talk) 16:57, 18 December 2012 (UTC)
 * I am not sure why, by declining to specify either the actual problems or what would constitute a satisfactory solution, Doniago has not just delegated to Spinningspark the decision to decide what of the challenged material needs to be sourced, and what does not. JohnInDC (talk) 17:25, 18 December 2012 (UTC)
 * (ec) You have not provided a list of facts as I requested. That is merely a dump of material you removed from the article - exactly what I asked you not to offer me.  What I want to see is that you are willing to actually put some effort into this instead of just demanding it of others.  Wikipedia is a collaborative effort.  That requires you to collaborate as well as everyone else.  Spinning  Spark  17:28, 18 December 2012 (UTC)
 * I would go ahead and add sources as you see fit, Spark. You will get either Doniago's effort or his acquiescence when you are done.  He will not be in a position to challenge your sources or your judgment without reviewing your work and measuring it against the text.  JohnInDC (talk) 17:47, 18 December 2012 (UTC)
 * I was in the middle of writing up something substantially longer, but I think you nailed it on the head there. Indeed, adding sources from the onset of this disagreement would probably have saved us all time, energy and frustration. Doniago (talk) 17:59, 18 December 2012 (UTC)
 * The problem as I see it Doniago, is not that this article cannot be verified, but that you do not want to put any effort into helping with that task at all. You seem to want to sit back and behave like an editor-in-chief demanding that your underlings do the work as you dictate and to a schedule you have decided.  Sorry, it does not work like that, we all work on what we feel like.  There are things on my to do list and proto-articles in my userspace that have been in the queue for years.  Why should this article (which I have had no input to so far and am not strongly interested in) jump the queue just because you have suddenly decided to lay down the law and threaten to tear it up if we don't comply?  I have made you an offer to use my technical knowledge to find sources if you will do the mechanical work of formatting and inserting them in the article.  You have thrown that offer back in my face.  So in reply to JohnInDC, no that is not going to happen, not because I couldn't do it - all the articles I write myself are thoroughly referenced and some have made featured status - but rather because it would stick in my throat too much to be made to do it by someone who is too lazy to do even a simple formatting task.  Or perhaps Doniago is afraid he might get some oil on his nice clean hands if he touches an engineering article?  Spinning  Spark  18:27, 18 December 2012 (UTC)
 * If and when you would care to rephrase that in a more civil manner I would be happy to offer a response. Doniago (talk) 19:55, 18 December 2012 (UTC)


 * A question for both Doniago and Spinningspark — Have you tried to find sources for any of the disputed material? If so, how did it go? Thanks, --Bob K31416 (talk) 18:13, 18 December 2012 (UTC)
 * Of course I have, where is that question coming from? And I have offered the results to Doniago here and here without anything constructive coming of it.  I also know enough about electric motors to know that the material is not complete bollocks and does not deserve wholesale deletion.  I also do not believe that the material is actually disputed - in the sense that the factual accuracy of anything is actually in doubt.  Spinning  Spark  18:46, 18 December 2012 (UTC)
 * Doniago has declined to try to find sources, stating that he is not an engineer and thus not qualified to identify or evaluate them. (Forgive me if I have mis-paraphrased.)  Spark offered to find sources (e/c - has found sources) if Doniago would identify what of the deleted material he believed to be in need of sourcing, but Doniago declined to be more specific.  As best I can tell, Doniago has no articulable substantive concerns about the text he removed; it is, rather, simply that the text at issue has no sources attached.  (This implies the converse, namely, that Doniago would be satisfied with any source that any editor might supply, but that's my own conjecture.)  JohnInDC (talk) 18:49, 18 December 2012 (UTC)
 * Beyond my unfamiliarity with the material, the simple fact is that I have very restricted web access from the location where I primarily do my Wikipedia editing. Google Books, for instance, isn't available to me. As I said above, if an editor wants to break down the statements in the unsourced sections and provide sources for them, I'm happy to add them into the article. I'm also happy to handle the job of digging the sources up myself, if and when I can...and until then I'm also happy to see the unsourced material remain here. I still don't see how I haven't identified the deleted material that I feel should be sourced...specifically, I feel the entirety of it should be. If sources were provided I might attempt to confirm that they back-up the material, or I might leave that to editors who are more invested in and knowledgable regarding the material. Frankly I think some of the editors here are trying to assign "responsibilities" for Wikipedia tasks that are not mandated by policy and that they are not in any position to attempt to delegate. I'm not disputing that Wikipedia is a collaborative process, but with regards to unsourced material that's been challenged, WP:BURDEN is pretty explicit. Doniago (talk) 19:51, 18 December 2012 (UTC)
 * The sure sign of disruption is when one editor insists on doing something against a group of good editors. NOTBUREAUCRACY means what it says, and attempting an RfC on something completely unhelpful for the encyclopedia (and after previous fails) is just disruptive. Johnuniq (talk) 20:46, 18 December 2012 (UTC)
 * Hmm...you're in a location where you have free and easy access to Wikipedia but you cannot get on Google books? Doniago, you certainly know how to push the boundaries of AGF. As you cannot read the source in gbooks, I will give you instead a link to WorldCat from which you can get the citation material.  The first line of the disputed material (and probably much of the rest of it) is verified on page 563 of this book.  Lets see if you do anything useful with that before I bother with anything more.  Spinning  Spark  21:43, 18 December 2012 (UTC)
 * For what it's worth, I had a look at the parts of the already cited Ref. [2] (I. Gottlieb) that are accessible on Google books and found that they closely back up most of the Special properties and Advantages sections. I could imagine that the entire article is based on the three existing references and just doesn't have inline citations for each individual statement.
 * The Special properties section essentially summarizes two topics, which are described and referenced in the linked Synchronous condenser and Utility frequency articles. Anybody with access to Wikipedia can follow those links and find the citations used there.
 * Funny enough, the Uses section was not objected to, even though most of it's statements are a summary of topics in challenged sections. I don't see how this makes sense. &mdash;&thinsp; H HHIPPO  22:40, 18 December 2012 (UTC)

The original question was: "whether it is best to leave unsourced material in an article that has already been tagged for this problem for over six months, or whether there are other options that should be considered/exercised".

The simple aswer is, both. You may remove it, even if there are large groups of editors working on the content. Many editors would see this as proof enough that there is no attempt to source content that is indeed questionable. But you have options as well. You can add a comment on the talkpage to warn editors that you will be removing the unsourced material and giving them even longer. Not always the best option as there is almost always someone who will reply that if it has been unsourced that long another 6 months wont hurt anyone. You could try to to do a search, but that has an odd sort of disruption of its own if you don't find something and another editor does, refuses to add it and then accuses you of not doing a good enough job or not understanding the subject. If you are an actual major contributer....you have just as much reason to remove it as others may have to say they want it kept. Edit warring IS NOT an option (just say'en).--Amadscientist (talk) 01:58, 19 December 2012 (UTC)


 * Okay, one more voice. I am an electrical engineer, took a rather meaty course in "Electromagnetic Machinery" using the Fitzgerald/Kingsley/et al text that is used to back up a few of the claims in the article, etc.  Having said that, much of the article, as is, is not so unambiguously clear to the typical Wikipedia reader that such a reader should believe the claims without sources.  There are numerous parts of the article that seem to make extremely specific, and often broad claims, all without any source whatsoever.


 * I see no reason at all that this article should get a pass from the rather ordinary parts of WP:V, which is after all, core Wikipedia policy, and includes the idea that challenged material should be either sourced, or it could reasonably be removed, after some period of time. Moreover, the burden of presenting evidence for the claims is on the editor who wants the material to remain in Wikipedia.  If the material is challenged, and then not sourced by someone who cares enough to do so within a few weeks or a couple of months, then the material may reasonably be removed until such time as sources are found and the material is cited.  This doesn't seem that hard.  Cheers.  N2e (talk) 02:08, 19 December 2012 (UTC)
 * Do you have your old textbook handy? --Wtshymanski (talk) 14:17, 19 December 2012 (UTC)
 * Yes, I do. And as of 31 Dec 2012 I have made a couple of edits to the article from that book.  I may try to do the research to cite a few more of the very large number of unsourced claims made in the article as it currently stands.  N2e (talk) 01:56, 31 December 2012 (UTC)


 * whether or not it was removed per wording of a specific current version of policy, the very very very very longstanding policy has required inline reliable sourcing to return material that has been challenged. If it is in so easy to source, the BEST thing for the Wikipedia article and the reader would have been for those who know its valid and have easy access to sources to validate it to do so rather than churning up the completely non-productive dramahz of "you did not indicate that you did not think that there were sources". this RfC is a complete waste of time.-- TRPoD aka The Red Pen of Doom  20:49, 19 December 2012 (UTC)
 * TRPoD, From your comment it seems that you wouldn't object if editors went from article to article deleting everything that wasn't sourced. Am I understanding you correctly? Thanks. --Bob K31416 (talk) 21:27, 19 December 2012 (UTC)
 * That does not appear to have any relevance to the RfC at hand. If you wist to have a philosophical discussion, feel free to come to my talk page. -- TRPoD aka The Red Pen of Doom  21:55, 19 December 2012 (UTC)
 * ✅. --Bob K31416 (talk) 22:15, 19 December 2012 (UTC)


 * Comment I have just received the RFC invite. I am not an engineer. I am professionally competent in certain empirically technical fields. My interest in and ambition for WP is that it materially contribute to the general good, rather than fulfill the ambitions of the formal definition and circumscription bloc, the ones that take the pride of the creator in the action of the wrecker. Fortunately we have none such in this discussion, but it behooves us to be perennially on our guard. Suppose in an article on horticulture I were to write about fairies at the bottom of the garden because I remember my old auntie etc... I find it a bit difficult to produce adequate citations (etc again)... A lot of hard-hearted sods descend on my article and plaster it with citation-wanted tags, or more likely they blowtorch it to destruction. Shaaame! How will WP endure without my deathless (but now dead) contributions?


 * But meanwhile my buddy is say, an engineer (substitute any alternative that suits your personal taste in metaphor) and he has achieved great stuff academically and greater stuff in the field. He has worked on the field of fraggling the graffles, both learning and expanding the general applied wisdom on the job, and formal research in the theory. He writes or expands articles on related, practically, theoretically and eruditionally important material. Much of what he says is assessable logically or on inspection. Some of it would seem trivially obvious to a seasoned practitioner, though obscure but enlightening to the intelligent tyro, and it might be beyond rubies to anyone without my buddy's depth of experience. Problem: only half of his stuff is citable, though it all is comprehensible, unobjectionable, even unchallengeable, to anyone with an appreciation of the field. For as long as only such people read it it remains unchallenged, only appreciated and maybe updated from time to time. Until -- along comes Willyerm Wikilawyer III, with his little book and points out that some of this stuff is uncited. (We will assume that we were fortunate to miss the attentions of his big brother Willburr, who just removes stuff that he doesn't like, especially from the work of people he doesn't like, so that he can accuse them of accusing him of bad faith). OK, so Willyerm is no expert; can't expect HIM to find or even assess suitable refs! So after a while a few experts with no other problems on their hands dig out some, any third-hand textbook that can be taken to support what any damfool in the field had known for decades and more or less rubberstamp most of the material with refs, but of course, some of it, though obvious to the understanding, isn't explicit in any accessible literature. Right! Now suddenly everything counts as OR and Synthesis and all that kind of abomination (see: it says so in my little book!) and Willyerm can cite chapter and verse for why it must come out no matter how useful it is to current users or future generations. Yippeee! No waiting in case someone does happen along with some citation, either very new or very old. Just zap it; the book of words says you can!


 * Now, exiting, if you go to almost any substantial article on substantial material, the probability that it contains such abominations as stale citation tags is closely mappable onto the scale of its value by any of a wide range of measures. As long as it is a matter of the personal taste of any adventitious editor with a chip, anyone can delete what he cannot create. I recommend that persons of good will (and sense) by all means 1)demand citations (dated according to taste) for uncited assertions. 2) remove all palpable nonsense, vandalism, irrelevant material etc. 3) Wherever there is any question about possible merit, remark helpfully on the talk page. 4) Where citation tags are getting really stale, ask nicely for someone either to demonstrate value or explain why not. (no explanation in a few weeks? Sure, you have a case for your blitz! Someone obviously doesn't care.) 5) Where an editor can support his claims of non-fringe expertise, leave it in place if he or his friends can say it is good. 6) unless someone else says it is rubbish (where doctors disagree, there are ipso facto grounds for deletion in the absence of independent support, as opposed to Wlawyering).


 * In short, where good will and expertise are present, improvement is worth waiting for. Maybe someday we will have everything perfectly cited (not in our lifetimes of course, but until then a citation wanted tag should be like a red link: an indication of something missing and an invitation to make it good. It should NOT mean an opportunity to wreck what should be mended. And that is what I think we have some of here. JonRichfield (talk) 08:39, 20 December 2012 (UTC)

Proposed Resolution
I am not by any means trying to short-circuit discussion here, but I feel it's possible that we've covered the major bases at this point. With that in mind, my proposal for resolving these issues follows. Other editors are welcome to submit alternate proposals or suggest modifications to my proposal. I hope we can agree that while we may take issue with others' perspectives on the matter, we all have the goal of trying to improve the quality of the article. Doniago (talk) 15:52, 20 December 2012 (UTC)

Proposal A

 * 1) The challenged information moved to the Talk page previously (see above section) will remain in the article for the time being.
 * 2) Any editor may provide citations for the information. This will immediately resolve WP:BURDEN concerns.
 * 3) Any editor may state their intention to provide citations for the information, said citations to be provided before February 15 of 2013.
 * 4) If citations are not provided for the entirety of the challenged material prior to February 15 of 2013, any of the material that was moved to the Talk page previously and remains uncited may be removed from the article, but will be retained here in the hope that citations will be provided in the future.

Proposal B
Doniago accepts that he has done quite enough here; if people care enough, something will happen, but if not, it won't.

Proposal C
WP:ESCA :) . Count Iblis (talk) 14:54, 23 December 2012 (UTC)

Discussion of Proposals

 * Support Proposal A Well, here goes nothing... Doniago (talk) 15:52, 20 December 2012 (UTC)
 * B - you know it makes sense William M. Connolley (talk) 16:57, 20 December 2012 (UTC)
 * B – Andy Dingley (talk) 17:23, 20 December 2012 (UTC)
 * B, voting is evil, but consensus should already be clear from the discussion above,  Spinning Spark  18:00, 20 December 2012 (UTC)
 * B. JohnInDC (talk) 18:41, 20 December 2012 (UTC)
 * B With due friendly respect to both sides and their views, but B. JonRichfield (talk) 19:15, 20 December 2012 (UTC)
 * Meanwhile passers-by marvel at the lengths Wikipedia contributors will go to to avoid actually cracking open a book and adding a citation. I'm surprised no-one has written Jimmy Wales about this yet. --Wtshymanski (talk) 14:23, 21 December 2012 (UTC)
 * I can't tell whether this comment is intentionally ironic... but it probably doesn't matter. Doniago (talk) 14:41, 21 December 2012 (UTC)

I can not believe that this came to an RfC as WP:V(A Wikipedia policy) is very clear on this issue and this edit by William M. Connolley (WMC) is a clear breach of of the Wikipeida policy WP:V "The burden of evidence lies with the editor who adds or restores material, and is satisfied by providing a reliable source that directly supports the material" (WP:BURDEN). Instead of discussing why WMC ignored policy and justifying why he has Ignored all the rules, which is necessary as it is he who is in breach of policy, WMC has chosen to make four comments, the first of which I think shows a lack of knowledge of WP:PROVEIT, and from there I think it just get less and less civil: I do not think that this these responses are constructive or help anyone to reach a consensus on what to do based on policies and guidelines.
 * B. Challenging material in the sense of WP:BURDEN does not mean that someone who is editing from an institution that gives them access to Wikipedia but not to Google Books and who doesn't have the slightest idea of what the material means suddenly jumps in and removes it for purely formal reasons. Legitimately challenging material requires a plausible argument why it may not actually be true. Editors who go around doing purely formal pseudo-challenges to material that appears correct to the experts are committing a denial of service attack on Wikipedia. Hans Adler 20:07, 23 December 2012 (UTC)
 * B Is anyone suggesting that the material in question is actually incorrect, or is the problem just that it does not (yet) have references? Martin Hogbin (talk) 14:36, 31 December 2012 (UTC)
 * 13:53, 17 December "‎Unsourced Material: I can't see where D has challenged the material" post
 * 17:19, 17 December 2012‎ "Unsourced Material: in that case..." post
 * 21:42, 17 December 2012‎ "RFC on unsourced material in previously-tagged article: how subtle" post
 * 16:57, 20 December 2012‎ "Proposed Resolution: B - you know it makes sense"

User:Spinningspark consensus is not clear from the discussion above. "Consensus among a limited group of editors, at one place and time, cannot override community consensus on a wider scale" (See WP:LOCALCONSENSUS) and the explicit wording of WP:BURDEN "The burden of evidence lies with the editor who adds or restores material, and is satisfied by providing a reliable source that directly supports the material". Your mention of "When tagging or ..." is advise to the person tagging or removing information. Once the text is removed from the article if you want to restore it you must provide reliable source for the text -- it does not matter what the motives of the person was for removing it (unless it is clear vandalism) and to question their motives is a breach of WP:AGF.

Having looked quickly at this article, I find it amazing how few citation there are in it! It comes under the WP:V advise I added as a footnote "It may be that the article contains ...". But in this case, given this debate and the vitriol that some have decide to use, I suggest that Doniago adds a tag to what (s)he considers to be the worst paragraph/section in the article and if it is not cited in a week it is removed (presumably it is one of the sections Doniago listed immediately above this RFC). It should only then be put back into the article if it can be cited with a reliable source. Once that paragraph is dealt with, then Doniago can repeat the process with another paragraph.

Spinningspark you wrote above in reply to Bob K31416 "...I have offered the results to Doniago here and here without anything constructive coming of it. ..." Why are you offering them to Doniago? Just choose the best one and add it as a an line citation to the appropriate fact in the article. Repeat until you have cited sources for all of the article.

If these methods are followed then in a short space of time this article will carry enough citations that the banner can be removed from the top and editors can drill down with citation needed templates for anything that remains a concern. Like so many other things finding citations for 90% of the text should not take long. The other 10% will probably take much longer and that is the text which will probably need to be moved to the talk page until citations can be found.

But to emphasise it again WP:PROVEIT states "The burden of evidence lies with the editor who adds or restores material, and is satisfied by providing a reliable source that directly supports the material" and that is because experience has shown us (Wikipedia editors with an interest in such things) time and again that this is the quickest way to take an unsourced article like this and get it up to good article status. -- PBS (talk) 22:51, 21 December 2012 (UTC)


 * It has already been pointed out that the sources already in the article, although not inline, pretty much verify the challenged material. The very first "fact" in the disputed material declares that this rotating machine has a rotor.  I for one am not going to run around after anyone writing up sources for this kind of "sky is blue" material.  By now, I have provided hundreds of citations for challenged material in technical articles in the past, and I am happy to do it when there is a genuine concern and is not just makework, but I am not doing anything here until we have a challenge to an actual dubious fact that might need citing.  Spinning  Spark  23:07, 21 December 2012 (UTC)


 * You of course do not need to do anything, but if something is removed then it should not be put back without an in-line citation to a reliable source. If you want to stop this process happening I suggest you follow what Blueboar said in response to the conversation you initiated Wikipedia talk:Verifiability

"::"In most cases, I actually find the complaints about the removal of unsourced information to be more disruptive than the removal itself. By far, the easiest and least disruptive solution to editors who remove unsourced text is to quietly return the material with a citation"."


 * With the time you have taken here and at Wikipedia talk:Verifiability arguing against what will have to be sourced, if you do know the subject you could have put in citations to reliable for all the text that was removed. This would have been a more long term constructive use of your time. BTW I practice what I preach for example earlier today I was looking at articles that were linked to an image of a piece of pavement in Edinburgh. When I came across one that I thought needed more citations I added them.
 * --PBS (talk) 23:34, 21 December 2012 (UTC)


 * Deleting information you already know is verifiable in order to force someone else to put in a citation is disruption of the worst kind and deserves blocking in my opinion.  Spinning Spark  00:41, 22 December 2012 (UTC)


 * I refer you to the Blueboar quote above. -- PBS (talk) 10:15, 22 December 2012 (UTC)
 * Repeatedly referring me to it is not going to help persuade me to do it. Why don't you do it yourself if you think it is such wonderful advice?  Spinning Spark  13:53, 22 December 2012 (UTC)


 * Everyone here understands the basic acronyms—no more links please! Anyone concerned about references should put the article on their to-do list and see if it needs attention in three months. This discussion is pointless and is approaching disruption. Johnuniq (talk) 00:44, 22 December 2012 (UTC)


 * The links help because one can not assume that the only people reading this page are those who have already contributed to the conversation, or are old hands, and personally I find it annoying to have to search on an acronym/initials with which I am not familiar to find out what a person means. -- PBS (talk) 10:15, 22 December 2012 (UTC)

I agree with PBS that "WP:V(A Wikipedia policy) is very clear on this issue and this edit by William M. Connolley (WMC) is a clear breach of of the Wikipeida policy WP:V "The burden of evidence lies with the editor who adds or restores material, and is satisfied by providing a reliable source that directly supports the material" (WP:BURDEN)."

So how do we go from here? It seems the material should not have been added back to the article on 2012-12-17T13:52:42 without an inline citation. If some editor wants to add that, great. If not, the contested material should stay out of the article temporarily until such time as it is cited. Cheers. N2e (talk) 17:32, 22 December 2012 (UTC)
 * No. The key here is in WP:V too: Wikipedia does not publish original research. No-one has challenged any of the material. No-one has suggested any material errors, inaccuracies, or any hint of OR William M. Connolley (talk) 20:23, 22 December 2012 (UTC)
 * Per WP:MINREF, the material was initially challenged when the article was tagged. It was subsequently challenged again when the material was moved here. Doniago (talk) 23:03, 22 December 2012 (UTC)
 * You're ignoring the consensus of proposal B above. Apart from that: you've misunderstood "challenged". Its not even clear if you understand any of the material; certainly you have not suggested any material errors, inaccuracies, or any hint of OR. Which is to say, you haven't challenged it William M. Connolley (talk) 23:19, 22 December 2012 (UTC)
 * It should be quite apparent at this point that other editors disagree with the "consensus" regarding proposal B; perhaps you're confusing "consensus" with "majority"? In fact, other editors who appear to disagree with proposal B have suggested a more conservative route than I suggested via proposal A. Whether you like it or not, tagging the material and later removing it is explicitly a suggestion of material errors et al...unless you can cite a policy that explicitly claims that doing such things is not a challenge to the material. Doniago (talk) 23:38, 22 December 2012 (UTC)
 * tagging the material and later removing it is explicitly a suggestion of material errors - no. Now you're just being tendentious. Read prop B, consider the support (everyone except you) and take the hint. Its a big wiki, there is plenty else to do William M. Connolley (talk) 09:59, 23 December 2012 (UTC)

WMC just because there are proposals that some of those involved in this RfC (consensus building exercise) have expressed an opinion it does not mean that there is a consensus. Your phrasing of proposal B is clearly a breach of the guidelines WP:TPYES and WP:FOC, and those who have expressed an opinion in that poll need to think if expressing opinions in that poll was constructive and if not they ought to strike through their stated opinion.

WMC you are not helping to build a consensus by making personal attacks on editors with whom you disagree and wish would go away. I have made a proposal at a compromise (that Doniago tags that sentence or paragraph (s)he things is the one most in need of a citation and those who know about this topic provide a reliable source for that sentence within the week or the tagged text is removed), and it would be helpful if you would concentrate on content. Doniago please mark the text in the article you think is most in need of a citation with a citation needed so that the discussion can get back to discussing specific content. -- PBS (talk) 11:27, 23 December 2012 (UTC)


 * PBS, I agree that WMC's proposal was bitey. It could have been phrased in a less incendiary way, but I agree with the sentiment and have no intention of striking.  Spinning  Spark  13:04, 23 December 2012 (UTC)


 * Doniago, I think you need to take a step back, get away from the legalese minutae of policy, and consider what the purpose of WP:V is. It is intended to ensure that the content of Wikipedia is verifiable.  So has that been demonstrated in this case?
 * An editor has examined the sources already in the article and declared they verify the material.
 * There have been no challenges to specific facts. Doniago has said that he is generally challenging the material  and does not have technical expertise.  But the article already has general references.
 * I have offered citations for specific facts in the hope of generating a more constructive discussion, and pointed out the vast number available for this well-known machine  but have got no response on what the actual issue is
 * Is this material really being disputed? Or is it more the case that some editors think it should have more little blue numbers?  The blue numbers mean nothing by themselves, they could say anything, one still has to read and understand the sources to be sure of verifiability.  It is the existence of sources that is important here, not the existence of little blue numbers.  Spinning  Spark  13:04, 23 December 2012 (UTC)
 * The problem, PBS, is that Doniago won't do it. Spinningspark offered to provide a source for any substantive element that gave Doniago pause and Doniago's response was, in essence, "it's all bad".  In his view, any text not directly tied to a source is properly removed until it a source has been supplied, or until an knowledgable editor makes the persuasive affirmative case that the particular assertion is so obvious that it does not need to be cited.  JohnInDC (talk) 13:11, 23 December 2012 (UTC)


 * The over a week-long ongoing discussion here managed to somehow skirt actual content-related questions, and long ago amounted to what could be considered trying to make a point. In the interest of actually improving the article, it would be better to actually provide citations for the paragraph in question, rather than to engage in what looks entirely too much like pettifoggery. — daranz [ t ] 21:21, 27 December 2012 (UTC)

"citation needed" at the end of a paragraph
Doniago would you care to let us know what it is that you find suspect in the paragraph you have just tagged? It would be some coincidence if you were just disputing the very last fact in the paragraph and the cn tag happened to be placed on the end. The lack of an explanation on this talk page leads me to conclude that it is merely a pointy tagging to see if you can intimidate someone into providing a citation, as a prelude to taggging the entire article, without any real concern that there is something wrong with the material.  Spinning Spark  19:36, 27 December 2012 (UTC)
 * I am specifically challenging the paragraph that I tagged. I felt that would be preferable to tagging each individual sentence, though I am willing to do so if you would prefer that. It should be noted that the entire article was already tagged over six months ago, and that I didn't feel any explanation was needed as I was encouraged to abide by PBS' proposal above, which I believe spells things out quite clearly and is a reasonable compromise. Cheers. Doniago (talk) 19:57, 27 December 2012 (UTC)


 * Doniago has added a citation needed template to a paragraph and in my opinion the information in the paragraph does not fit into the category, so it does not seem unreasonable to me that if the information in this paragraph is to remain in this article it should carry one or more inline citations to one or more reliable sources. -- PBS (talk) 20:36, 27 December 2012 (UTC)


 * Doniago, you have been opposed by numerous editors, but feel a single editor supporting you is enough justification. Are you sure you really want to challenge the entire paragraph?  Are you really disputing that a sychronous machine rotates in synchrony ("the armature winding creates a rotating magnetic field, which revolves at the designated motor speed")? Perhaps you didn't really mean to challenge Faraday's law of induction ("acts as a synchronous generator (alternator) and creates a very large counter-current that opposes the rotation".)?  And PBS, surely the fact that large currents might trip the overcurrent breaker is a "sky is blue" fact if ever there was one.
 * Doniago, the offer to find sources was a test to see if you were really interested in collaborating on improving the article. Nevertheless, it was a good faith offer; in the past I have spent the entire week looking for sources for other editors.  As part of article review processes I have made special arrangements for access to sources only available in universities and museums and have made special trips to London to view them.  This article is far more straightforward to source than any of that, but it is now quite clear to me that you have no desire whatsoever to collaborate on work on the article and merely wish to mechanically poke other editors with undefined templates then mechanically delete if you don't get a response.  Discussion of the actual issues seems to be anathema to you.  I really don't think there is any realistic way you can be induced to collaborate.  My conversation with you is over and I withdraw any offer I made to work with you on the article (although that decision does not apply to any other editor).  Spinning  Spark  21:26, 27 December 2012 (UTC)


 * Spinningspark you do not have to work on this article or take part in this RfC. There is a general consensus that material that is challenged should carry inline citations, and a number of editors apart from myself have said so in this RfC, the most recent being daranz (see here). As to your comment "And PBS, surely the fact that large currents might trip the overcurrent breaker is a 'sky is blue' fact if ever there was one" I think it ignores other phrases in the full sentence "More supply current is needed to overcome this resistance to motion, which results in a power draw so large that it may trip the overcurrent protection." and that the complete sentence is not a "sky is blue" fact. -- PBS (talk) 21:51, 27 December 2012 (UTC)
 * I am not trying to oppose the principle that challenged facts must be provided with an inline citation. What I am opposing here, as you must surely by now know from the thread I opened at WT:V, is the idea that it is acceptable to systematically go through the wiki challenging all uncited material without any consideration other than the lack of little blue numbers.  I further oppose the notion that it is helpful to actually delete uncited material when one is fully aware that reliable sources for it exist.  Spinning  Spark  00:31, 28 December 2012 (UTC)
 * By the way, here is a ref for the high start current .  Spinning Spark  01:01, 28 December 2012 (UTC)


 * I agree with Spinningspark. 'Challenged' means that an editor, with reasonable cause, asserts that something that is written is incorrect.  In that case the onus is no the restorer to provide a reference.  'Challenged' does not mean that a passer by noticed that a particular word did not have a reference.  As others have pointed out, that attitude is very disruptive to the writing of an encyclopedia. Martin Hogbin (talk) 14:48, 31 December 2012 (UTC)


 * I don't suppose you were not involved in the debates in 2006 and the need for better quality articles. It is a disservice to reader to expect them to take the word of Wikiepdia editors that what they write is correct. See for example the article the Battle of Waterloo and the difference between end of 2006 and end of 2007 the text had not changed much, but the reliability of the article had improved immeasurably, because the text was by then using inline citations to reliable sources. For those involved in developing the article, most the minutiae of the battle is well known (it is the most written about battle in history) and for those editors it was citing obvious facts. But for those who are not familiar with the battle such citations allow them to check that what is written in the article is accurate. If a fact is not commonly known, there is no reason why an editor who is an expert on the subject of an article, should not provide a citation to a reliable source in that article (even if it is commonly known among such experts). As each English language country teaches different types of general knowledge to their school children, it is likely that the common knowledge among English speakers is lower than it would be if the population was largely contained within one country (as it is with many European nations). -- PBS (talk) 15:47, 31 December 2012 (UTC)
 * No, I was not involved in that discussion but it seems to be mainly an essay by one editor. It has no special weight here.
 * I agree entirely with the idea presented above by PBS. No matter how much esoteric knowledge is inside the heads of knowledgeable Wikipedia editors, the encyclopedia is for our readers, and we should endeavor to improve articles over time to the current WP citation standard.  The policy is quite clear, folks may challenge unsourced material; if they do, it is the responsibility of those of us who want the unsourced material to remain in the Wikipedia to add citations.
 * I added a number of additional cites to this article yesterday. Let's get to work, and improve the article.  But in the meantime, there is nothing wrong with other editors, who may or may not be technically inclined, from requesting such citations, and after a time, removing material that is not sourced.  N2e (talk) 16:09, 31 December 2012 (UTC)
 * Yes WP policy is clear and it does not say that unsourced material should be removed just because it is unsourced. Of course should endeavor to improve articles over time by adding references but drive-by deletions are not part of this process. Martin Hogbin (talk) 02:38, 1 January 2013 (UTC)
 * PBS, no one is maintaining that more citations are not a good thing. It is gratuitous deletions which are bad here.  Your example is not a particularly good one, by your own admission the text of Waterloo is largely unchanganged.  Do you not see the logical fallacy of arguing that more citations improves articles because they end up with more citations?  If this had not been such a well-known subject with many editors on hand willing to respond, it might have ended rather differently if it had been given the Doniago treatment.  Most articles have few watchers and deletions go unnoticed.  With large swathes of the article deleted, it would be much harder to provide citations for material that is no longer there and in the meantime it would be a much poorer article.  Spinning  Spark  10:23, 1 January 2013 (UTC)

You will find more on outside opinions on this page: External peer review. One of the article to which it has a link is Can you trust Wikipedia? (2005) which is not the hatched job written by some journalists that year but the title give you an idea of what was being asked. This part of a posting I place on the talk page of WP:V a few months ago:

There was a paragraph in the article "Battle of Berlin". An edit was made 17:55, 17 November 2004 which included the sentence "That the battle ended after a week of heavy fighting was mainly because the German supply dumps were located outside the Inner Ring and were captured quite early in the battle by the Soviets, ..." by an IP address which stopped editing long ago, and long before general references inline citations were the norm in such articles. There were two problems with that sentence it expresses an expert opinion (OR) and it contains a fact "the German supply dumps were located outside the Inner Ring". I added a "citation needed" to the paragraph on 16 July 2007. The sentence was cut and pasted into the more specific article "Battle in Berlin" and then removed by me on 10 January 2009. The dumps sentence had been "preserved" for four years of which it was tagged "citation needed" for a one and a half years. I removed it because it was not sourced (PROVEIT) in an article in which all the rest of the text was sourced. It was not that I did not think it possible for it to be true, but it could also have been false and to quote the Jimbo footnote in BURDEN "There seems to be a terrible bias among some editors that some sort of random speculative 'I heard it somewhere' pseudo information is to be tagged with a 'needs a cite' tag. Wrong. It should be removed, aggressively, unless it can be sourced."

It was not that the facts in the sentence were unverifiable, (In fact I recently came across a source that verifies it (Tony Le Tissier Race for the Reichstage (2010) [1999] p. 74), but leaving unverified text in an article that turns out to be unverifiable is worse than removing unverified text that turns later is found to be verifiable (In World War II the BBC was trusted because it told the truth (even if not all the truth), German wireless was not trusted because it was know to lie). Part of the process of building a useful encyclopaedia is to have articles that the public expect to be factually accurate. Without that expectation Wikipedia will be seen a second rate source.

Which was the reason for the debates in 2006 because in 2005/2006 Wikipedia was getting a lot of stick by journalists for containing false information. Since the move to PROVEIT this problem has lessened. Drive by deletions are not accurate way to describe the process as most of those get reverted as vandalism. But text removed, with an editorial or a comment on the talk page that asks for citations should not be put back without inline citations (as pre WP:BURDEN), unless there is a good reason to not to include a citation. For example that the text is in the lead and is a summary of text in the main body of the article, in which case that should be explained on the talk page, and agreed to before it is put back. -- PBS (talk) 00:59, 2 January 2013 (UTC)


 * Again, you have given an example that speaks against you. You deleted a fact that later turned out to be true, so I am not really seeing your point.  In any case, we are not really talking here about difficult to source stuff as in your example.  Most of the material being challenged here can be verified with 30 seconds of gbooks searching.  Spinning  Spark  07:18, 2 January 2013 (UTC)


 * There has been an RfC and the consensus is fairly clear. Information which a person thinks is incorrect may be removed pending a reference.  Information should not be removed just because it does not have a reference.  There is not, and never has been, a policy requiring this.Martin Hogbin (talk) 09:36, 2 January 2013 (UTC)


 * Agreed. We remove material that is unreferenced if it is reasonably challenged. the word "reasonably" is not   explicitly in the policy, because it's unnecessary: it is implied in every WP policy and guideline. It's based on the idea that we are trying to build an encyclopedia,not engaging in a referencing exercise.  FWIW, the most accurate and reliable WP is the German WP, where detailed referenced are not required for material that is not controversial and easily found in a library or textbook; they in fact have quite a few unreferenced articles, accepted because there are standard sources that educated people are supposed to know about & do not have to be specifically quoted. I would not go that far, because we, unlike they, have a substantial world wide audience many of whom are without knowledge or access to sources. And, truth to tell, even with respect to the major English-speaking countries, we are writing for, on the average, a somewhat less educated audience than  they. As mentioned above, we are writing for an audience which does not necessarily have a basic understanding of physics and technology. This means our articles have to be somewhat tutorial. Trying to cite tutorial material at a basic level is both frustrating and unnecessary.  DGG ( talk ) 02:25, 3 January 2013 (UTC)

'Keep material. I got a request from the FRS, I've not been involved in any way with this page before. I read about half of the above WALL OF TEXT. I was an electrical (e.g. electronic outside of the US) engineer, and this is basic stuff (components of a motor being a rotor, etc.) that anyone who has studied a semester of engineering knows. This is like a citation for "the sky is blue", as it is memorably put in some guideline or policy, but I can't remember which one. I don't have textbooks to hand (I'm now a seminarian and a novice monk), so I apologize for not being able to do my part and source the material book, chapter, and verse, and just be another voice calling out to keep. St John Chrysostom ΔόξατωΘεώ 11:59, 6 January 2013 (UTC)

'Keep material and add citations in due course. The article should be improved by adding citations - and this is happening. The material in the article appears to be good material, so it does not want deleting. The tags are useful as they prompt people to add citations.

The issue appears only to be the old uncited/needsmore tags
Summary: '''The beatings of this article will continue until editor morale improves and they start citing everything that I am demanding, and I will continue to delete large swaths of this article's content, regardless of its correctness, of which I know nothing about, until my demands are met. Policy is on my side so you demoralized editors who feel you are being unfairly treated by me have no recourse except to bow down to my will, or see your work on this subject matter mercilessly ripped to pieces by me and the might of my deletionist hammer (backed by bureaucratic policy of course). Hahaha! Neener neener neener!'''

As unpaid editors contributing good faith high-quality technical edits of their own free time, some editors may feel that being repeatedly "shouted at" and "called on the carpet" by an overbearing and unrelenting managerial deletionist *******, they find it rather difficult to spur the motivation to comply to the deletionist's every whim.

The solution to this current debate seems rather simple. A knowledgeable editor such as Spinningspark merely needs to look at some of the cites already included in the article, and declare the cites included already fully cover the entire breadth of the article, and thus remove all such uncited/needsmore tags, perhaps inserting a few new ones for just specific sections.

Doniago is unable to dispute removal of said needsmore/refneeded tags because it has already demonstrated it knows nothing of this subject matter other than the presence of said tags.

Doniago who knows nothing of this subject matter and apparently does not care to involve itself in such matters such as actually knowing anything about the topic, and merely narrowly focusing on old cleanup tags, without knowing the meaning of either the text or the cites, is now left with nothing to do because all the old refneeded/needsmore tags are removed except find another article to start vandalizing in the name of "improvement".

(Like player piano maybe? -- oops, sorry, Doniago is already busy deletionist vandalizing that one, another narrow technical topic of little-dispute but alas not well cited and (gasp) needsmore tags more than (gasp) six months old, so it DEMANDS the heavy-handed Doniago to delete ANY further additions if uncited, ever. I was going to start expanding and improving it but after some run-ins with Doniago he took all the fun out of even trying to start improving it.. so **** it, the article can rot.)

Cites? Yes, eventually. If it's a real problem for you personally, you are certainly free to add them if you actually care to learn anything of the subject matter.

However, deleting what you don't understand in a technical subject matter article simply due to the presence of a old refneeded tag seems rather unproductive and divisive, and unlikely to get the quality results you are arrogantly demanding of the other unpaid volunteer editors of the article.

And yes, I know we're supposed to discuss the topic, not the editors, but this really is a lot about Doniago's deletionism attitude and demeanor, which reminds me more of a schoolyard bully than an adult editor contributing to the knowledge enhancement of millions of people.

Doniago makes no attempt to either cite or verify anything, it only deletes based on the presence of aged cleanup tags, which may themselves be of dubious placement by people who also don't understand the subject matter.

Doniago's editing methods do not inspire camaraderie and cooperation with other technical subject matter editors, who are most likely going to continue trying improve and cite these articles, even after Doniago has moved on to some new article to flog.

When we have other uninvolved bureaucrats come in and say But he does have policy on his side it is exactly like some schoolyard bully running to tell on the other kids and then triumphantly smirking while seeing the other kids get in trouble. It makes for a very divisive and abrasive working environment. The other kids just want to reach through TCP/IP and whack said bully with a large trout.

-- DMahalko (talk) 05:21, 31 December 2012 (UTC)


 * Ooops, my mistake. According to policy, you don't need to declare to anyone here that you know anything about a topic to edit it. We don't care about degrees or experience.


 * So rather than requiring some editor known to be knowledgeable of the topic to remove citeneeded tags, we really only just need some random anonymous IP editor to decide the article is cited well enough (even if they don't understand the article at all) and remove all said global article needsmore cite tags because they believe the article doesn't need them.


 * And that's the end of this whole debate, because Doniago and none of the other bureaucrats commenting on this issue have sufficient knowledge of the subject matter to know if said cite-needed global markup tags should be added back. -- DMahalko (talk) 05:42, 31 December 2012 (UTC)


 * Raised at Administrators'_noticeboard/Incidents Andy Dingley (talk) 03:53, 3 January 2013 (UTC)

The only thing in the article that appears to be misleading is more of an undue weight issue related to power factor correction. It's not very prevalant now to use motors for PF correction as it's mostly capacitor banks that are used for that. Not every synchronous motor that is manufactured can run with PF > 1. It's fine for a general article on the theory of synchronous motors and citing the obvious is not necessary unless there is a contention that can be articulated. --DHeyward (talk) 06:18, 3 January 2013 (UTC)

Self-starting small motors
N2e, you have placed citation needed tags on self-starting small motors and indicated that you doubt the mechanism described is the reason for self-starting. I cannot find any accessible sources on this in gbooks, would you mind posting exactly what your Fitzgerald source has to say on this. It is fairly obvious that if it can be managed to drag the rotor around 1/4 of a turn in the first half-cycle then the machine is going to start rather than just sit there humming. Whether this happens clearly depends on the rotor inertia and the force being applied to it. The force in turn is dependent on the rotor current and the strength of the stator field (dependent on stator current). That just has to be the main consideration and I would think the article is basically correct on this. You mentioned variable reluctance: it is true that there will be a greater reluctance in the coupling between rotor and stator fields when the rotor poles are inbetween stator poles (first at 1/12 of a turn) so that is where the rotor is going to stall if anywhere, but with sufficient momentum to get past that point it will probably start.  Spinning Spark  16:56, 31 December 2012 (UTC)
 * Sure. I'll try to find some time to get back into that source, and see if I can't find a better description of the mechanism.  I'm quite certain that it's not "low mass" as is asserted in the article.  N2e (talk) 01:57, 2 January 2013 (UTC)


 * ✅ Finally had a chance to get back here and crack that book open.  I left a quotation from Fitzgerald ch. 11 (p. 537) in the article where I had previously requested a citation.  It was moment of inertia and its associated mechanical load that are the key factors to making self-starting possible.  If anyone wants to copyedit that paragraph so the quotation is less prominent, and less geeky, fine by me.  Cheers.  N2e (talk) 00:55, 9 January 2013 (UTC)


 * Many modern/recent "introduction to motor technology" sources appear to flatly state that self-starting is simply impossible for all purely synchronous motors regardless of size, but they do not delve into why it is impossible or attempt to explain it, which suggests they either don't know and are parroting some prior source without understanding, or don't believe the discussion is important.


 * I found one old source that suggests self-starting is possible through other than armourtisser / squirrel-cage induction, but the method of explaining is technical and so requires careful reading and distillation. It is itself well-cited, but seems to be lacking a publication date, and is hard to look up on search engines:


 * The Starting Conditions in Synchronous Machines.
 * By Prof. A. Hay, D sc., M.I.E.E., and F. N. Mowdawalla, M.A., B. SC.
 * http://eprints.iisc.ernet.in/43487/1/The_Starting.pdf


 * Then there's this one, discussing huge industrial synchronous motors "in the 10–20 megawatt power range":


 * ... Compared to the traditional synchronous motors with laminated rotors, whose starting torque is developed from the damping bars on the rotor, the starting torque of solid pole motors is developed by the eddy currents induced on the surface of solid-pole shoes. It is a much more complicated process..


 * ... In order to shorten the design cycle, many efforts have been focused on the modeling of motors using nonlinear magnetic circuit approach and equivalent circuit method [14]–[20]. However, most studies are focused on the laminated salient pole synchronous machines with damping windings on the rotor surface, or induction motors, not for solid-pole synchronous motors [21]–[24]. Analytical solutions were derived from magnetic field theory for round rotor solid pole motors [25]...


 * Modeling of the Starting Performance of Large Solid-Pole Synchronous Motors Using Equivalent Circuit Approach
 * Chunting Chris Mi, Yongbin Li, and Haran Karmaker
 * Department of Electrical and Computer Engineering, University of Michigan, Dearborn, MI 48128 USA
 * Electrical Research and Development, TECO-Westinghouse, Round Rock, TX 78681 USA
 * IEEE TRANSACTIONS ON MAGNETICS, VOL. 45, NO. 12, DECEMBER 2009
 * http://www-personal.engin.umd.umich.edu/~chrismi/publications/2009_45_12_TMAG_Solid_equi.pdf


 * -- DMahalko (talk) 12:59, 2 January 2013 (UTC)


 * Re modern sources saying self-starting is impossible: that probably reflects the rarity of fractional horsepower synchronous motors today. Synchronous motors have very low self-starting torque, but for a clock-sized motor that's enough to get them going. For bigger motors, friction, inertia, and load are too much for the low starting torque to overcome, so they're usually started as induction motors.  Looking around for pictures of synchronous motors, the market today seems to consist of 1) large (>1 HP) industrial motors, usually 3-phase, 2) servomotors used with electronically controlled drive systems, and 3) clock-type motors for microwave oven turntables and similar applications. The latter will (usually) self-start.   John Nagle (talk) 21:22, 4 January 2014 (UTC)
 * It turns out we have a good article on Shaded-pole synchronous motor, with a clear picture of a disassembled motor and its shading rings, so I added a reference to that and removed some of the detail. John Nagle (talk) 21:42, 4 January 2014 (UTC)


 * I used to have an electric clock with a synchronous motor and it was not self-starting. The rotor had to be spun by hand to start it. I accept that a Shaded-pole synchronous motor could be self-starting but it has always been my understanding that an ordinary synchronous motor of any size cannot be self-starting because it has zero starting torque. Biscuittin (talk) 15:33, 17 August 2015 (UTC)
 * They can (and were) made self-starting, often by adding an effective squirrel cage on the rotor (squirrel cages are self-starting) where, once it's up to synchronous speed, there is zero slip and thus it's no longer working as an induction motor. The drawback is that even a stationary shorting bar can have losses. it can also be done with an additional mechanism as a phase shifter, controlled by a starting switch or a centrifugal switch. These could be capacitor networks, an extra pole alongside or a shortable turn across part of the pole to shade it.
 * It's important to remember the difference between slip and phase. Slip is necessary for an induction motor. Slip implies non-synchronous operation. So synchronous motors also require brushgear and slip rings that can be avoided with induction motors. Yet it's not a requirement that any "large" motor runs with some slip, as if often claimed. Large synchronous machines can run without slip, so long as there's a phase difference between rotor position and the stator fields. If it lags, it operates as a motor; if it leads, it's a generator.
 * Synchronous operation isn't often needed in large sizes (induction motors may be preferred) but one field that did always need them are synchronous motor-generator sets for frequency and phase changing. Andy Dingley (talk) 16:11, 17 August 2015 (UTC)
 * One widespread use of shaded-pole synchronous motors was record players of the pre-audiophile era. Here's a picture of one: . Note the clearly visible copper shading rings.  I can't find a cite on the theory, although there are plenty of how-to articles on repairing record players which show such motors. John Nagle (talk) 05:58, 18 August 2015 (UTC)
 * Shaded poles are inefficient though (losses in the shorted turn) and don't scale up to large motors. Where that's used for starting, it's a temporary feature and the copper turns are only connected through a switch. Andy Dingley (talk) 09:13, 18 August 2015 (UTC)

At the moment, the citation about self-starting small motors has a closing quotation mark, but it never opens. I have no time to find out where it is supposed to open or if this is still a literal quotation or has been edited. The person responsible for inserting it please check and fix. Thanx!! Nicola.Manini (talk) 08:27, 19 January 2023 (UTC)

Well done
In the last month I think that the reliability of this article has improved greatly and I would like to thank those who participated in the now closed RfC and all those who have directly contributed in a collaborative effort which has taken an article that a month ago did not even have a general references section to to one that now has over 30 inline citation (including multiple citation to the same sources). -- PBS (talk) 01:50, 18 January 2013 (UTC)


 * I concur. The article is much better now, now that sources have been provided for a lot of the claims in the article, and now that a variety of assertions that were made in the article as of two months ago have been rewritten or removed.


 * I believe we owe thanks to the editor who made the first move to eliminate the material which had previously, for many months, gone with sources being requested but no editor surfaced who cared enough to fix the claims or add the citations. That editor took a fair amount of incivility from other editors questioning her/his motives, especially during the early weeks of the RfC.


 * The improvement of Wikipedia is an emergent outcome, and it often takes a BOLD edit by a concerned editor to kick off the process of improvement. So I merely add, "Well done" to BOLD and civil edits, and the editor who made them here to get this article on a path to improvement.  Cheers.  N2e (talk) 16:47, 9 February 2013 (UTC)


 * It's in much better shape now. The motor starting section could use a little improvement.  We could use some more modern pictures.  The giant M-G set from 1909 is a poor first image. I added a picture of a Teletype motor (1800 RPM synchronous), but that's a 1930s design. Would someone please take a good photo of a modern ordinary synchronous motor of modest size?  Not something exotic, just a vanilla 3-phase synchronous industrial motor without variable speed controls. Thanks.   --John Nagle (talk) 08:35, 4 January 2014 (UTC)
 * Cleaned up the starting section, but we still need some good pictures of modern motors. John Nagle (talk) 21:43, 4 January 2014 (UTC)

Risk of accident due to stroboscopic effect
When running the motor on the same power grid as the lighting, rotating parts of machinery may be mistaken for standing still due to the stroboscopic effect (depending on type of lighting), which may lead to serious injury. I remember reading about actual accidents of that type, but do not find any reliable sources. — Preceding unsigned comment added by IgnoranceIsntStrength (talk • contribs) 16:02, 6 March 2014 (UTC)
 * I have _never_ found a credible report of such an accident. It's a popular tale though. It begins in the 1950s when many workshops etc. were being refitted or built with the new fluorescent tube lamps, rather than incandescent. As these have a (very weak) stroboscopic effect, there is a possible effect as you describe. It's not a feature of motors specifically though, as motors are rarely accessible directly and most of the "rotating machinery hazards" would be geared at some ratio to the motor speed anyway – thus synchronous motors aren't significantly more affected. Despite that, this is a very persistent tale. There have been no end of dire warnings that machine tool worklights must use incandescent bulbs, rather than fluorescent. A few years ago, the UK began to phase out incandescent bulbs for efficiency reasons in favour of compact fluorescents. One exception though are that specialist incandescent bulbs are still permitted, such as "rough service" bulbs used in this type of worklamp (they're far more fragile than fluorescents). It has also been suggested that this exemption is because of the "fluorescent bulb strobe effect".
 * In fact, fluorescent bulbs aren't significantly stroboscopic anyway. They generate visible light from phosphors coating the tube, not directly from the tube's discharge, and these phosphors have sufficient persistence to keep glowing adequately in the 100Hz troughs. Also compact fluorescents, and many modern luminaires, use high frequency ballasts anyway, with a strobe frequency far in excess of mains frequencies.
 * OTOH, LED bulbs nowadays do often show stroboscopic effects. Many of those used to retrofit 12V halogen dichroics, with electronic switch mode PSUs rather than transformers, are simply unusable. Andy Dingley (talk) 16:15, 6 March 2014 (UTC)

Unsourced material - article tagged in January 2014
Article has been tagged for needing sources long-term. Feel free to reinsert the below material with appropriate references. DonIago (talk) 19:00, 12 August 2014 (UTC)

Here we go again
As my attempts to clean up unsourced material in this article are once again being reverted in violation of WP:BURDEN, I have requested assistance at WT:Verifiability. It would be agreeable to see this situation resolved without significant escalation. DonIago (talk) 19:37, 16 December 2014 (UTC)
 * Tell you what, I've already added one reference. Let's each of us dig up a reference and add it and we can reference the hell out of this article. Deleting whole paragraphs of basic facts is extremely lazy editing. --Wtshymanski (talk) 19:48, 16 December 2014 (UTC)
 * If I thought I was well-suited to provide sources for this article then I would be doing so. Unfortunately that is not the case. Perhaps other editors will be better able to assist you. DonIago (talk) 19:53, 16 December 2014 (UTC)
 * You've at least got the Internet. Google Books is a fascinating trove of data, though I admit an awful lot of their recent electrotechnical content seems to come from a small number of very prolific authors. You might even have a library; more than once I've checked out a book to provide references to a WP article. --Wtshymanski (talk) 21:08, 16 December 2014 (UTC)
 * I've made some effort to find sources for the unsourced material, with a regrettable lack of success. Unfortunately given that the article has been tagged long-term, I'm not really surprised by my lack of results; I would hope that other editors would have been able to provide sources by now if they were available.
 * Under the circumstances I'm forced to return to my original conclusion: that the material hasn't been sourced because it cannot be sourced, and should be removed until such time as references can be provided. If you feel otherwise I would be happy to discuss other options for resolving this matter. Perhaps we could stipulate that the unsourced material will be permitted to remain in the article for another month or so, at which time it will be removed. That will give us and any other invested editors additional time to find sources before the material is removed.
 * Obviously, rather than simply being deleted, the material could be moved here as well, where invested editors would still be able to easily locate it if at a latter time they were in a better position to locate sources. DonIago (talk) 13:47, 17 December 2014 (UTC)
 * I don't know what sources you're been looking at, but I don't recall seeing anything in this article that isn't "black letter" and old in the art - there's no novelties here. Could you specifically mention at least one item you think is dubious? There's a million books on AC motors, it's all standard textbook material and I am someone incredible that you can't find sources for the banalities listed here. --Wtshymanski (talk) 15:19, 17 December 2014 (UTC)
 * Oh, I see.. this goes back to 2012 and you still can't find any references. Not even Google Books? No library? No bookstore? Nothing? --Wtshymanski (talk) 15:22, 17 December 2014 (UTC)
 * As I'm not an expert on this subject, it's entirely possible I just don't know where to look. And if people who presumably are more familiar with the subject evidently can't find sources when they've had months to do so, it doesn't seem realistic to expect someone unfamiliar with the subject to have better results. I did spend some time checking online resources last night; as I mentioned, I was unsuccessful. As I said earlier, I'm not someone who is well-positioned to be providing references for this article.
 * In any case, this isn't about you or about me; one way or another the unsourced material has been unsourced for a very long time (or unsourced material was added to the article, which was a questionable notion if the article was tagged at the time), and we should be focusing on a way forward. As I said, I'm amenable to leaving the unsourced material in for the time-being with the understanding that a good-faith effort is being made to locate references, but I think we're past the point where the material should be retained indefinitely. Thank you for your understanding. DonIago (talk) 15:40, 17 December 2014 (UTC)
 * Doniago, the clue here for me is that you write "As I'm not an expert on this subject ...". For me as a reader, rather than as an editor, I am quite happy to see material flagged as citation needed and it can stay that way for ever if no one comes along to provide a citation. I get the benefit of the material and the citation needed flag allows me to make my own evaluation. It is incredibly patronising of you to deny me access to that material because it does not meet your standards for citation - and when you admit that you are not an expert in the subject, from my perspective, what you are doing borders on vandalism.
 * I suggest that the threshold for removal of uncited material is that you either know it to be wrong or you have good reason to doubt it. Otherwise you should do no more than flag it as uncited if not already flagged. After that you should leave it alone for ever for someone to come along to cite. If you remove it, the person who would otherwise come along to provide the citation may never recognise that the material you have removed could be reinstated. As far as I can see you do not dispute any of the material you have removed.
 * Wikipedia will never be perfect. But it can still be more than excellent if it is comprehensive and the possible points of imperfection are identified, Your striving for perfection is driving the article away from excellence and is concealing the scope for improvements. I ask you to revert all your edits, except those that meet the test that you either know it to be wrong or you have good reason to doubt it.78.32.68.244 (talk) 11:42, 21 December 2014 (UTC)
 * Regardless of your feelings as an individual reader, Wikipedia policy allows for the removal of unsourced material, and I believe the consensus has been established that unsourced material should not remain in an article for a great deal of time without any references being provided. WP articles are intended to be encyclopedic in tone, not allowing for "here's some stuff that may or may not be true".
 * It is misreprensenting the situation to say that the material doesn't meet my stnadards for citation; in fact, the material I am concerned with has no citation at all. If you'd like to accuse me of vandalism for removing unsourced material for which citations were previously requested, WP:ANI is over there. If not, then drop the personal insinuations and focus your arguments on the issues at hand.
 * As the material went without citation for months I feel I do have good reason to doubt it. If the material is verifiable, why has nobody verified it in all that time? In this particular case the situation is even more notable, as we already went through this argument previously. One might think that invested editors would not want to set up a repeat of the situation.
 * Your feelings on "excellence" include allowing for statements for which no form of verification has been provided; my feelings are that an excellent article provides references rather than mixing potentially inaccurate information in freely with information that can be verified.
 * I have already asked for other options previously; I note that you, similarly, did not provide any. Wtshymanski and I were willing to make an effort to locate sources; are you? As always in these types of arguments, the most effective way to resolve the issue would be to provide citations where they can be provided. DonIago (talk) 17:21, 22 December 2014 (UTC)
 * Yes, OK. You admit you are removing material on the grounds that it is uncited while at the same time stating that you are not an expert. If I wanted to vandalize material in a domain about which I know nothing, I have learned from you that I could just identify a load of stuff as uncited and delete it months later. Now, I do not think for one moment that you are setting out deliberately to vandalize. But take note that I am a consumer of Wikipedia - ie a reader and not an editor on this topic. As such, the fact (citation needed) that you are not setting out to vandalize means that I do not feel so bad about you as a person. But it does mean that, regardless of your motivation, I feel as bad about the material itself as if you were doing this deliberately.
 * On the topic of synchronous motors, I fancy I may know more than you do, but I am staying in the role of consumer-reader rather than producer-editor, so I will not be providing citations. I am disappointed that you cannot leave alone (save for 'citation needed') and let me make my own evaluation of the material.78.32.68.244 (talk) 22:53, 22 December 2014 (UTC)
 * It is not vandalism to delete material for which a source has not been provided assuming you have concerns about whether it is verifiable; rather, policy explicitly supports removing material on such grounds. In fact, tagging it first, while arguably best practice, is also not a requirement. Wikipedia is intended to be an encyclopedia where articles contain facts, and when those facts are not plainly obvious to a general readership references are provided so that readers can verify information should they wish to do so; articles should not be compilations of information that may or may not be true. I appreciate your views, but they are not in accordance with policy.
 * I am open to options short of removing the material (and optionally relocating it here), but I am not being presented with any, and after months of no improvement it is past time that this matter was addressed. DonIago (talk) 13:39, 24 December 2014 (UTC)
 * Anything which is valid is ultimately verifiable. You can only truly say it is not verifiable if you can say it is invalid. If you delete stuff which is not verifiably unverifiable, you risk deleting valid material. As long as the citation needed flags are in place, there is less damage done by leaving the material in place than by removing it in this subject domain. You are doing little more than making a strong case for me that Wikipedia's policies are actually damaging to coverage of the Engineering domain.78.32.68.244 (talk) 22:44, 24 December 2014 (UTC)
 * If it's verifiable, then prove it by providing sources. Otherwise stop claiming that it is. There is no policy requiring that editors prove information is unverifiable, and how would one do so in any case? Your personal views on this matter are not in accordance with Wikipedia policy, as has been explained to you at WT:V, and given that Wikipedia's intended to be a general encyclopedia, not one geared towards the engineering domain, I have little sympathy for your concerns.
 * Put another way, at this point I don't believe the information is verifiable and consequently don't believe it's valid. If I'm wrong, prove me so by providing citations. DonIago (talk) 02:24, 25 December 2014 (UTC)
 * Your position on validity and verifiability is, as you so aptly demonstrate, a matter of belief, not fact. You are on a mindless zealot crusade and what is more you have won the argument [without convincing me that there is any merit whatsoever in your crusade] because Wikipedia policy supports you. So be it. Wikipedia's policies here are deficient. I am not going to run around after you providing citations, when I am content with the material and a citation needed flag. As you say Your personal views on this matter are not in accordance with Wikipedia policy. but let us state this more accurately, if you are fairly representing Wikipedia, then it is Wikipedia policy which is out of step.78.32.68.244 (talk) 09:17, 25 December 2014 (UTC)
 * On that note, I do believe I'm done talking with you about this. DonIago (talk) 13:09, 25 December 2014 (UTC)
 * The note was: I am done with giving you time of day. Your contribution to Wikipedia is detrimental.78.32.68.244 (talk) 17:04, 14 January 2015 (UTC)

Missing efficiency information
The average efficiency of an synchronous motor is told nowhere in the article, or at least i can't find that information. I think it should be added to the article. Ojakokko (talk) 14:20, 14 February 2016 (UTC)


 * ✅ Greatly varies in general, for large motors above 95%. Викидим (talk) 01:46, 1 September 2023 (UTC)

Physically wrong statement
In "operation" section we have "The operation of a synchronous motor is due to the interaction of the magnetic fields of the stator and the rotor. " This cannot possibly work because fields do not interact with fields.

If you put a magnetic field A in the presence of a magnetic field B, what you get is a magnetic field C that is the sum of the other two, and that is the end of the story.

To move your rotor, you need to create a force or a couple of forces acting on it. You will not find in physics a formula that says field + field = force.

To create the force, you need to have the stator field interact with a magnetic moment in the rotor. Though the name is close, it is a different beast entirely. A magnetic moment is a representation of the configuration of electric currents in an object. That may be macroscopic currents, that you create by applying some power supply to a coil, or it may be a collection of intrinsic currents in matter like for example the electrons running on their orbits around the nucleus. Electrons also have intrinsic magnetic moments for reasons i do not pretend to understand. Those intrinsic currents are for the case of permanent magnets, for example. Of course, they also exist in any matter, but in ferromagnetic materials, at least a portion of those moments can be aligned to a given direction under the influence of a magnetic field, thus creating a net macroscopic effect, whereas in ordinary objects they remain scattered in all possible directions and cancel each other out.

So when you put two magnets close together, you do not feel forces because the fields of both magnets act upon one another, but because the field of one magnet acts on the magnetic moment of the other, and vice versa. If you think about it, you will realize you only feel the force in the magnet themselves, because the magnetic moment is tied to the material of the magnet, it cannot radiate away from it, the electric currents are internal. If fields could act on fields, since they spread from the magnet in all the space around them theoretically up to an infinite distance, you would have a force field filling the space around the magnets, which as far as i know, is still the stuff of science-fiction. Now in physics you do have a formula that creates a force out of a field and an electric current : F = I.dl ^B (vectorial product), and for rotating systems : Torque = (magnetic moment) ^ B.

So your sentence should read : "The operation of a synchronous motor is due to the interaction of the magnetic field of the stator, and the magnetic moment of the rotor."

This is true for all the electric motors i can think of, though sometimes in a less obvious manner. — Preceding unsigned comment added by Metazoaire (talk • contribs) 22:58, 19 June 2016 (UTC)

Clock drives
I added clock drive under the "see also" header, because it must be related. But I cannot work out from the article if clock drives are a special case of these motors, or whether they work on the same principle. Someone who knows can perhaps integrate it into the article. JMK (talk) 19:03, 25 August 2018 (UTC)

Power versus Horsepower
I'd like to get some comment on the use of Power versus horsepower to describe these motors. Line 22 states Synchronous motors are available in sub-fractional horsepower self-excited sizes. I think the term "horse" has no place here unless we are quoting the power output of these motors in Watts or horsepower. Avi8tor (talk) 13:14, 10 January 2019 (UTC)


 * Use both (you are trying to push this same viewpoint across many articles and it's still wrong). Use the Convert template, per our normal practice. Andy Dingley (talk) 13:17, 10 January 2019 (UTC)


 * The convert template is being used, you misinterpret the suggestion. Are you suggesting we should say "Synchronous motors are available in sub-fractional horsepower/power sizes"? They both mean the same thing, but Power is a word that addresses both horsepower and Watts (kW/MW). Avi8tor (talk) 04:39, 14 January 2019 (UTC)
 * "Sub-fractional power" makes no sense. "Sub-fractional horsepower" means less than 746 watts. This could be added in parentheses if necessary. Bradv 🍁  18:54, 31 January 2019 (UTC)
 * Since everything can be expressed as a fraction, there's no need for "sub fractional horsepower". Why don't we just stick to what the motor standards and catalos say and refer to them as "fractional horsepower" ? --Wtshymanski (talk) 21:25, 31 January 2019 (UTC)
 * That's a good point – "subfractional" is redundant. "Fractional horsepower" would work just fine. Bradv 🍁  23:26, 31 January 2019 (UTC)


 * See User talk:Avi8tor too. Andy Dingley (talk) 12:26, 1 February 2019 (UTC)

Explanation of SSC would be appreciated
SSC motors are said to be much more efficient than others. An explanation in the article of what they are and why efficient would be appreciated.

With exceptions, the article in general seems to be written with little mention of energy efficiency. Adding comments about the efficiency of the various technologies would be nice for someone looking at buying a motor for, e.g. the blower on an air conditioner. Ocdcntx (talk) 01:18, 12 July 2023 (UTC)


 * (1) The sensor-based and sensor-less speed control (the latter is SSC) should be a section of the Vector control (motor). Here we most likely need just a brief mention of it in the, probably, PMSM section (and in the BLDC article). (2) Efficiency is a interesting topic, but belongs in the Electric motor article, most likely (or even a separate, yet unwritten, Efficiency of electric motors (we have a weak Premium efficiency about the marketing term). Reason for this topic being out of scope here is simple: the motors types vary by application, so PMSM, for example compete on efficiency not so much with regular SMs, but with induction motors. Викидим (talk) 20:56, 12 July 2023 (UTC)