Talk:Induction motor

message: The article only mentions single-phase and three-phase AC induction motors.  There are also two-phase motors used in special applications (with the phases separated by a 90 degree phase angle).  Is this worthy of inclusion? Maybe just mention that single and three phase are the most common?  Tqcurtis (talk) 14:10, 8 January 2009 (UTC)
thread_title:  Two-phase AC Induction Motors 

message: It seams like somebody keeps wanting to incorrectly change the voltage referred to in the Speed Control section to 33V and not 25V, so I think I had better explain.
If the signal is ON for a third of the time that it is off then there are 4 quarters (3 off, 1 on) therefore the average voltage over this period will be 25V (A quarter of 100V).
how to work of celling fan motor ?  — Preceding unsigned comment added by 2409:4053:78D:AB1C:B4B4:1D39:75E3:7631 (talk) 18:12, 28 February 2019 (UTC)
thread_title:  Speed Control 

message: 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) 18:21, 28 December 2007 (UTC)
thread_title:  Spam 

message: I did a micro edit. Formulas => Formulae, since formulae is the plural of formula.  —Preceding unsigned comment added by Lambda driver (talk • contribs) 10:02, 21 August 2008 (UTC)
thread_title:  Micro edit done. 

message: Galileo Ferraris discovered the Rotating Field Principle, and put the basis for the Theory of Induction Motors. I think that he needed to be mentioned in the "History" paragraph!
-- An Italian Engineer --  —Preceding unsigned comment added by 81.112.253.226 (talk) 12:45, 26 November 2008 (UTC)
thread_title:  Don't forget Galileo Ferraris!! 

message: Not all inductions motors are squirrel cage motors (i.e. with short-circuit rotor). Often the rotor actually has a winding with brushes, which can be connected to external resistors to increase the slip to decrease the rotor speed (useful for start-up without frequency converter or for slight speed variations). Still these brushes are much more rugged than the DC motor commutator brushes. User:Nillerdk (talk) 11:27, 6 February 2009 (UTC)
thread_title:  Comment to introduction 

message: Just want to comment on the good work. The first few introductory paragraphs couldn't be better.Dave3457 (talk) 21:37, 23 June 2009 (UTC)
thread_title:  Good work 

message: in 3 phase induction motor ,how many wire are used  —Preceding unsigned comment added by 123.236.46.27 (talk) 08:02, 30 June 2009 (UTC)
replies: text:  Usually six, two wires per phase, thus you can decide if you connect them delta/star. On some small motors they may be just three wires accessible (hardwired to delta/star inside the motor). -- 92.203.32.193 (talk) 16:09, 2 August 2009 (UTC)
thread_title:  induction motor 

message: Historical proves that Tesla "identified" (weird verb, usually exploited by someone who want to prove something without evidence. Usually inventors just publish, create, patent...)are non existent. The fact is that Tesla spent most of its energies by trying to create a mith of himself through letters or memorials. He was simply obsessed not to be recognised as the first having invented or applied or thought something......Tesla was aware that Ferraris had created induction motors in 1885,three years before him (1885 Ferraris's models still exist where are those created before 1888 by Tesla?), and just put about the history of the idea conceived in 1882. No priority on a discovery can be given to Tesla or to anyone else just refering to memorials based merely on owns testimonies without any rigorous evidence.  —Preceding unsigned comment added by 193.136.94.218 (talk) 17:00, 8 September 2009 (UTC)
replies: text: Definitely: The Tesla fan-boys should read "Nickola Tesla, His Work and Unfulfilled Promises" by Laurence A. Hawkins who was a contemporary of Tesla and was disgusted with Tesla's constant scrabbling for the limelight. (see https://archive.org/details/TeslaUnfulfilledPromisesHawkins) Gutta Percha (talk) 11:00, 27 September 2014 (UTC)
thread_title:   No evidence that Tesla identified or applied the magnetic rotating field before 1888 

message: June 10th 1883 in France, 
Tesla demonstrated newly completed A.C. induction motor before Mr. Bauzin, former mayor of Strasbourg, and several potential investors. They watched the motor with interest, but it was apparent they did not understand the value of the invention.
No evidence? Plenty of people saw it work, including people that helped him build the presentation in the city center.   —Preceding unsigned comment added by Alser (talk • contribs) 03:13, 2 December 2010 (UTC)
replies: text: So I could say that my grand-grand father "conceived" the theory of relativity in 1900 and explained it in front of the mayor of his village to see the face of Einstein substituted with that one of mine ancestor in every book around the world? History of science requires rigorous evidences and the 1883 presentation (presumed) has no historic consistency. Galileo Ferraris never wanted to patent any of his inventions yet he didn't "conceive" but built induction motors (models still exist) in 1885 and showed them working to everyone visiting his laboratory, this is the only consistent historical fact.  Magnagr (talk) 10:58, 2 December 2010 (UTC)
thread_title: What? NO EVIDENCE

message: The equation seems to be missing from the "AC Induction Motor" Section:
"
:AC Induction Motor
:where
:n = Revolutions per minute (rpm)
:f = AC power frequency (hertz)
:[...]
"
Shouldn't there be an equation between the heading and "where"?  —Preceding unsigned comment added by 72.236.152.194 (talk) 14:53, 19 May 2010 (UTC)
thread_title:  Missing Equation for Induction Motor Speed? 

message: Independently from Tesla, and, probably, at the same time, Ferraris inventedand made a laboratory model of two-phase induction motor. He obtained the magnetic field by passing two phase-shifted alternate currents through two coilsphysically shifted for 90 degrees. The rotor consisted of a cylinder made of copper. Although knowing very well the electromagnetic theory, he made two
mistakes in the analysis of the function of that motor: he neglected the leakage of the flux in the rotor, and he observed, nobody knows why, the efficiency at maximum power of the motor. Because of the first mistake he could not Tesla’s Polyphase System and Induction Motor understand why the motor does not have the highest torque at start, and because of the second mistake he came to the wrong conclusion that that motor can not have the efficiency higher than 0.5. That conclusion provoked the famous Ferraris’s statement, often mentioned when people talk about the need of caution when coming to theoretical conclusions without practical check, that a motor made in such a way, that means the induction motor created by polyphase alternate currents, can not be of use in industry to transform electric energy into mechanical work. What a mistake of a talented inventor and respected professor! Marcel Deprez, Bradly and of others who also described the devices in which the rotation of the rotor was achieved
by polyphase currents, but they have mistake. Therefore is mentioned that Tesla invented the first practical induction motor!!!  More --Свифт (talk) 15:48, 25 April 2012 (UTC)
replies: text: See section above on this very point. DieSwartzPunkt (talk) 18:18, 30 September 2012 (UTC)
thread_title: Practical induction motor

message: The reference for Tesla's first induction motor patent in this article is a 1996 book, "Lance Day, Biographical Dictionary of the History of Technology, page 1204" (ref 8), and it gives the first Tesla US induction motor patent as #381,968. This is the wrong patent, as I detail below. (Note my dispute has nothing to do with priority claims between Tesla and other inventors.) I claim the Tesla patent being identified as his first induction motor is simply the wrong Tesla patent. Tesla's first induction motor is actually to be found in his patent #382,279, which he filed six weeks after #381,968.  
An examination of the referenced patent, #381,968, shows this motor to be a synchronous motor, specifically a variable reluctance synchronous motor. The patent figures clearly show an asymmetrical rotor, and the text describes the rotor as operating at exactly the same frequency as the rotating magnetic field, which is the key characteristic of a synchronous motor.
In Tesla patent #382,279, filed just six weeks later on Nov 30, 1887 (issued May 1, 1888), we see he has changed the rotor. Now the rotor has two single-turn shorted coils made of copper plates. The text makes clear that under load it runs slightly slower than the stator magnetic field. (In modern terminology it 'slips'.) And Tesla notes this motor has a "powerful tendency to rotation", which I think is his way of saying this motor has much more starting torque than his earlier synchronous motor. The motor of patent #382,279 is clearly an induction motor, so this article should reference this patent as the first Tesla induction motor.
The best reference I know for this is an essay on induction motors written by me, posted on my homepage , and I would like to change the Tesla patent reference to this essay. My credentials: 40 years as a motor control design engineer (retired), MIT graduate, 14 US patents several on induction motors, and since I retired and had an interest in motors I made a serious study of Tesla's early motor and generator patents. 24.61.212.124 (talk) 05:51, 4 October 2012 (UTC)
replies: text: Feel free to make changes. Wikipedia does have guidelines for  citing yourself. In a nut shell from what I have seen the gist is "if you are an expert and have written well researched material on a subject then you should easily be able to cite the sources you used for your own material". The tricky bit is when you cite primary sources. Wikipedia does not encourage interpretation of primary source material unless you can cite where that interpretation has already been made in multiple peer-reviewed generally accepted secondary sources. A personal website also does not meet the WP:RS secondary source standard. Not that you have to master any of that to make a change or edit, if you want to make an edit that seems sensible, it will probably be right.  Fountains of Bryn Mawr (talk) 14:19, 4 October 2012 (UTC)
thread_title:  Wrong Tesla patent is referenced 

message: I like Andy's suggestion that we allow "invisible elves" as an alternative explanation; after all, it can't be refuted by a reliable source. You'd also have a hard time finding a reference that says eddy currenrs aren't DC. I quoted a couple of books but who cares about that, they aren't on-line and so must be wrong.  --Wtshymanski (talk) 17:11, 22 October 2012 (UTC)
replies: text: They're related to the lift demons that keep aircraft flying. Andy Dingley (talk) 19:06, 22 October 2012 (UTC)
replies: text: I suppose you think you have to resort to insults, since you have no valid arguments so far as I can tell. Physics textbooks are reliable sources and not fiction.Embrittled (talk) 21:25, 22 October 2012 (UTC)
replies: text:  The theory is spreading:  Andy Dingley (talk) 12:45, 23 October 2012 (UTC)
replies: text: Well, that isn't actually, technically, a reliable source in Wikipedia's definition, but it should at least have given them pause for thought; professors aren't usually flatly wrong about things like that. There's another example (about 31 minutes in and 47 minutes in) of  this being taught as Eddy currents at MIT. Of course, that's not a reliable source(tm) either, but this is a reliable source:  and says the same things. Embrittled (talk) 15:34, 23 October 2012 (UTC)

text: Please note that Guy Macon is currently using those above pages to engage in multiple acts of hypocrisy revert warring, and major battlegrounding.Embrittled (talk) 20:46, 31 October 2012 (UTC)
replies: text:  Please stop attacking other editors. If you continue, you may be blocked from editing Wikipedia.  --Guy Macon (talk) 03:00, 1 November 2012 (UTC)
thread_title: Fiction in Wikipedia

message: Hopefully I come to the right place. I have a question concerning with the torque-speed curve.
I did quite a bit search on google and the model calculations I found based on equivalent circuit of a transformer are not good enough to me.
http://www.uotechnology.edu.iq/dep-eee/lectures/3rd/Electrical/Machines%202/IV_I.Machines.pdf
http://www.scribd.com/doc/18815834/188/Equivalent-Circuit-of-3-Phase-Induction-Motor-at-Any-Slip
http://www.scribd.com/doc/27304673/Torque-Slip-Characteristics
http://www.ece.ualberta.ca/~knight/electrical_machines/induction/basics/trq_speed.html
http://what-when-how.com/induction-motor/developed-torque-induction-motor/
Most calculations are based on the equivalent circuit, usually referred to as "transformer equivalent circuit". The key point of the derivation is that the part of the rotor which transforms electric energy into mechanic energy can be viewed as a resistance and its value is associated with the "slip" (s) by
:R_r = \frac{R_2}{s}\, 
Using the circuit diagram on this wiki page, one can determine the power consumed by this resistance, it reads
:w = |\frac{\varepsilon}{R_s+R_r+j X_r}|^2 R_r\,
         = \frac{\varepsilon^2}{(R_s+\frac{R_2}{s})^2+X_r^2} \frac{R_2}{s}\,
 
Note that X_s does not enter the expression since it does not affect the power consumed on R_r  once the input potential \varepsilon  is given.
If one notices that the power is associated with torque \tau and rotation speed of the rotor(not the "slip") \omega (up to some constants) by the follows
:w = 2\pi r \tau \omega,
 
If one assumes that  \omega is big enough therefore it can be treated as a constant, 
:\tau = \frac{1}{2 \pi r \omega}\frac{\varepsilon^2}{(\frac{R_2}{s}+R_r)^2+X_r^2} \frac{R_2}{s}\,
 
Above expression of the torque \tau as a function of slip  s (and assuming everything else as constants) possesses exactly the feature shown in the plot on the page, and is reproduced from the above sources I have cited. A more realistic model may introduce more parameters but it will adopt essentially the same key features. 
HOWEVER, look closely, the above model does not sound realistic to me at all. I will give two arguments below. First, let us for a moment consider that the the stator circuit and rotor circuit in general are physically separated (as in a transformer) and consequently they do have different currents, namely, i_1 and i_2. If one want to establish an equivalent circuit diagram as the one shown on the page, one has to take more care when calculating its effective resistance R_r and reactance X_r. Considering two extreme cases. (1) When s=0, no induction will be present in the rotor circuit, therefore i_2=0 but in general i_1 \ne 0. (2) When s=1, no work will be done, hence no energy transforms at all, this implies that the effective resistance is (almost) zero in the rotor circuit and the reactance is basically an inductance. In general one has i_1\ne 0 and i_2 \ne 0. Note that these two cases are corresponding to end-points on the torque-speed curve. Now if one think the motor as a transformer, one should have 
:\frac{i_1}{i_2} \approx \frac{N_2}{N_1} = Const.\,
where N_1, N_2 are the corresponding turns. Obviously, here is not the case. The second argument is simple, the rotation speed \omega in the above derivation is in fact associated with the "slip" by the following relation
:\omega = Const.\times (1-s)\,
This is simply because the later is related to the difference of rotation speed between the stator and the rotor and the former is the rotation speed of the rotor. If one substitute this into the above expression, one no longer gets the "desired" torque-speed curve, so what now?
Following this line of thought, I actually tried to write down a proof by myself (a model of course, which reproduces the main feature of the observed torque-speed curve) and it turned out to be very different from the derivation shown above that I got from google.
I am not at all familiar with electronic circuit (except from those from college physics textbook), I am quite confused at this moment. If possible, could anyone please point out a source where one may find a well-established and well-recognized explanation, thanks in advance.
Gamebm (talk) 15:12, 8 November 2012 (UTC)
thread_title:  Torque-speed curve, a short discussion on its derivation 

message: It would be incredibly helpful if ya'll could re-write this lead. As it is, you pretty much have to already know what an induction motor is in order to understand it. Sometimes we forget that we're not writing these things for other experts, but for 6th graders and people who know zero engineering terminology.
Go 'head and nerd yourselves into oblivion in the body of the article, but please, for the sake of humanity.... re-write the lead as if you're explaining it to someone who's never heard of an induction motor. Seriously. Just try.
THANK. YOU.--Atlantictire (talk) 02:47, 19 June 2014 (UTC)
thread_title: Lead issues

message: "Synchronous speed
An AC motor's synchronous speed, n_s, is the rotation rate of the stator's magnetic field,
n_s={2f\over{p}},
where f is the motor supply's frequency, where p is the number of magnetic poles and where n_s and f have identical units.[26][27] That is, for a four-pole three-phase motor with two pole-pairs set 180° apart, p equals 4, thus n_s = {2f\over{4}} which equals 25 Hz (1,500 RPM) and 30 Hz (1,800 RPM) respectively for 50 Hz and 60 Hz supply systems."
Although I am an electrical engineer, it is many decades since I last thought about induction motors.  Hence I read this with the fresh eyes of the uninitiated:-  "That is, for a four-pole three-phase motor with two pole-pairs set 180° apart".  Apart from 'that is' instead of 'for example', I have this to say: As I understand it, the windings on the stator of a 3-phase motor will typically be of the distributed type, making it difficult to identify individual poles, but nevertheless the winding will produce a rotating field similar to that produced by a salient-pole type having 3 pole faces for a '2-pole' machine, and 6 for a '4-pole' machine.  Thus 'poles' is being used in a particular and potentially confusing way, by analogy with the construction of a single-phase motor. The simplest type of three-phase stator (a 2-pole stator) actually has 3 magnetic pole faces.  Moreover, in a 3-phase stator the physical pole faces are at 120 degree intervals around the stator in the first case (2-pole), and 60 degree intervals in the second (4-pole). so 'set 180° apart' also has a specialised jargon meaning which very few readers will understand.  Only a motor specialist will understand that 'two pole-pairs set 180° apart' actually refers to a physical arrangement which can be more clearly described as 'two pole-triplets each occupying 180 degrees of the stator'.  Or, alternatively '3 pole-pairs R-R', Y-Y', B-B', set at 60 degree intervals'.  Would someone like to sort this out ?  — Preceding unsigned comment added by 82.37.54.83 (talk) 07:02, 13 April 2016 (UTC)
thread_title:  This should be made more clear ! 

message: "An induction motor therefore does not require mechanical commutation, separate-excitation or self-excitation for all or part of the energy transferred from stator to rotor, as in universal, DC and large synchronous motors."  I suggest this as a replacement:- "An induction motor can therefore be made without electrical connections to the rotor as are found in universal, DC and synchronous motors."
I particularly dislike "for all or part of the energy transferred from stator to rotor" does this refer to electrical power converted to mechanical power (in which case it would be inappropriate for a dc machine), or to electrical power supplied by a separate source such as an exciter (in which case the power is not transferred from the stator).  — Preceding unsigned comment added by 82.37.54.83 (talk) 07:34, 13 April 2016 (UTC)
thread_title:  I also don't like this... 

message: "Paraphrasing from Alger in Knowlton..."
This phrase makes no sense in this context, nor can Google shed any light on it. Can the author link it to an explanation (or just delete it)?
Mark.velocino (talk) 16:18, 31 July 2016 (UTC)
replies: text: It was added here, and is referenced.GliderMaven (talk) 20:04, 31 July 2016 (UTC)
thread_title: Huh?

message: I've seen multiple references recently to something called an Advanced Induction Motor, a few web searches suggest this is not just marketing language, but a change in technology for building induction motors suitable for low-speed operation, and useful in marine propulsion systems. https://www.researchgate.net/publication/3973201_The_Advanced_Induction_Motor It would be great if technology received more coverage in Wikipedia.
Burt Harris (talk) 20:04, 11 December 2016 (UTC)
thread_title: Advanced Induction Motor?

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thread_title:  External links modified 

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thread_title:  External links modified 

message: I believe the most relevant and misunderstood thing about 3 phase pole motors isn’t addressed. People see 3 main wound coils and don’t understand how and 3 legs feeding but don’t understand how you get 2 poles. They don’t understand only 2 coils have magnetic energy while the third coil is feed by equal energized legs equaling out or having little potential. The graphic showing 4 magnetic fields 90 degrees out equally confuses and misleads people as is 120 degrees. I look at other google recommendations for motor poles and most seem to not explain or just copy off wiki and copy the same mistakes  Ox1111 (talk) 18:09, 20 December 2017 (UTC)
thread_title:  Pole pair explanation  

message: According to, for example, Ottó Bláthy:Kálmán Kandó, started work at the electrical section of the Ganz Works in 1894, understood that Nicola Tesla's induction engine could be used for railway traction. He and Bláthy began to investigate the problems of three-phase electric system including the traction. Bláthy developed the one-phase generator and transformer into a three-phase one and it was he, in fact, who actually improved the phase-converter electric locomotive devised in 1923.
According to, for another example, Biography of Otto Titusz Blathy}:Blathy’s interest was also aroused by the three-phase system. (The system was discovered by the British engineer Hopkinson in 1880, when he realized that three alternating currents in phase shift with each other can be transmitted easier than normal alternating current.) Otto Titusz Blathy developed the up to now one-phase generator and transformer into a three-phase one.
The lesson here is that in principle the induction motor and the transformer are very similar and Steinmetz's equivalent circuit for the induction motor is essentially the same except for the motor slip having to be accounted for.
Bottom line, Induction motor#History's 2nd sentence that follows below here is definitely in error:The first commutator-free single-phase AC induction motor was invented by Hungarian engineer Ottó Bláthy; he used the single-phase motor to propel his invention, the electricity meter.  
His genius stems from inventing a single-phase generator and a single-phase transformer that were successfully used to work as a three-phase electric system. But he did not invent the induction motor. Cblambert (talk) 03:12, 30 January 2022 (UTC)
thread_title:  Otto Blathy invented the induction-based transformer but not the induction motor 

message: The 37th link is dead, requires replacement or addition source to provide further explanation 2607:FEA8:7A64:300:282A:3BF9:220E:432F (talk) 18:26, 25 March 2023 (UTC)
thread_title:  Link 37 dead