Talk:Leakage inductance/Archive 3

Archive 1

Archive 2

Archive 3

Notes / copyedit

The amount of discussion belies the amount of real work done on this article. It appears that outside EE's possibly associated with research institutions, rather than seasoned WP editors, have been in charge here.

Lead

• Leakage inductance derives from the electrical property of an imperfectly-coupled transformer whereby each winding behaves as a self-inductance constant in series with the winding's respective ohmic resistance constant, these four winding constants also interacting with the transformer's mutual inductance constant. The winding self-inductance constant and associated leakage inductance is due to leakage flux not linking with all turns of each imperfectly-coupled winding. What?
• Leakage flux... acting as an inductance in series with...?? Consider the electric circuit equivalent of that statement: (some kind of)current... acting as an inductance in series with [a resistor]. That makes no sense at all: current isn't inductance and doesn't act like inductance, and neither does flux. Inductance is a derivative of a magnetic vector field at a fixed point; flux is a quantization of the field. We don't want to go into vector calculus here, but we should be very clear for the purpose, what the terms actually represent. Maybe we just want to say in the second phrase (since the first phrase referred to leakage flux), "...; the resultant leakage inductance is a series inductance." (inferred to be in series with the self- or mutual inductance).
• Although discussed exclusively in relation to transformers in this article, leakage inductance applies to any imperfectly-coupled magnetic circuit device including motors. Wordy -> "Leakage inductance applies to any imperfectly-coupled magnetic circuit device."
• last para of lead - we don't do references in text like that - move to footnote

Section 1

• This section is a lengthy juxtaposition of two disjoint topics and should be split into separate sections
• it says: The magnetic circuit's flux that does not interlink both windings is the leakage flux No! No! No! It is the magnetic flux NOT traveling in the magnetic circuit that interlinks both windings, which is the leakage flux.
• eq. 1.3, 2.1 and 2.9 are duplicates; eq. 2.1 is replicated in the sidebar
• In eq.1.1, substituting in for the right-hand side, I get $L_{P}=L_{P}$; when I do the same in eq.1.2, I get $L_{S}=L_{S}$. Are these supposed to be definitions?...axioms?...identities?
• At the bottom of section 1 and again in the sidebox, $a^{2}$ is used, but '$a$' is not defined
• Section 1 sidebar uses terms, additive and subtractive series connection. This procedure is not described, and is not patently obvious
• In section 1 sidebox, Campbell bridge is not described, but used as if familiar. No reference to it can be found in the encyclopedia.
• In eq. 1.3, $\left|M\right|$ appears, but '$M$' is undefined; below, $L_{sc}^{sec}$ is defined but not used
• In Inductive coupling factor subsection, it says, Per Eq. 2.7, but eq. 2.7 hasn't been seen yet

Section 2

• This section is a lengthy juxtaposition of two disjoint topics and should be split into separate sections (see also section 1)
• In section 2, it says five impedance constants as shown in the diagram at right, but I see 13 symbols, presumptively constants, in that diagram
• It appears that five impedance constants may refer to $L_{P}$ and $L_{S}$; these constants are inductances, not impedances; their associated impedances must be their inductive reactances, $X_{L_{P}}$ and $X_{L_{S}}$
• Eq. 2.2 uses symbol '$a$', but the text uses symbol 'a' - just distracting; anyway, the turns ratio is more conventionally and mneumonicly designated '${\mathcal {n}}$'.
• The term mesh equations in section 2 isn't described.
• Eq. 2.10 is a duplicate of eq. 2.2
• eq. 2.14-teeny, tiny little text - use "math /math"
• $a=N_{P}/N_{S}=v_{P}/v_{S}=i_{S}/i_{P}={\sqrt {L_{P}/L_{S}}}$ ------ (Eq. 2.1) I don't like this at all: only one of these things defines the turns ratio; it may be approximately inferred from the other relations, which are measured quantities, and such inferred ratios are likely to differ from each other and from the defined value.

Section 3

• justification for this whole section is absent: "refined" with respect to what? Why do we need a refined factor, and how much better is it?
  • I note that this section was deleted in its entirety once, and my gut feel is that it should be so again, or the whole section moved to a footnote
  • Refs for this section are a college course handout, no longer available and not commercially published; these are not valid citations per WP:RS
• the stuff in eq. 3.7 duplicates the derivation in the sidebox
• most of the reductions in eq. 3.7 are superfluous anyway - move the algebra to a footnote, the encyclopedia is not a math textbook
• Section 3: teeny, tiny little font - use "math /math"
• Section 3 sidebox references eq. 3.7a-e, but there are no such equations.

Section 5

• It says, i_M is magnetizing current excited by flux Φ_M. Figure 5 in that section is of the electric circuit. Without a corresponding diagram of the magnetic circuit, we really don't know where flux Φ_M flows. We're mixing models here and the result is uncertainty.

Applications section

• In applications section, it says Leakage inductance can be an undesirable property... In many cases it is useful. That's an untenable clash in semantics.

Overview

• can't discriminate knowns from unknowns in equations, or constants from variables
• what's important? If I pick up any random numbered equation, I don't have any sense of its relevance
• no discussion of techniques to reduce leakage inductance, like interleaved winding layers, bifilar windings, toroidal cores, etc
• article uses two different methodologies, open-circuit and short-circuit to compute the various measures, without any discussion of their validity, trade-offs or applicability. We never use transformers in short or open circuit, so it casts doubt on the whole article.
• there is no definition of leakage inductance, coupling factor, leakage inductance factor, or the 'inductance constants' (we compute something for them but it doesn't matter what we compute if that doesn't correspond to what we want assessed; and what is that?
• The symbol $=$ in many, maybe most, cases doesn't represent relational equality, but a whole variety of other relationships like assignment, 'is defined as', 'implies', 'may be inferred from', 'is congruent to', 'may be represented as', and etc. The ambiguity renders equations as written confusing and just plain inaccurate.

This article needs some serious work in technical diction/accessibility, organization, presentation, formatting and copyediting. Sbalfour (talk) 02:50, 27 November 2017 (UTC)

Validity of sources

I would like to comment about the vadility of sources such Hameyer's 2001 course document, which was available only until at least 2013 and which, some are of the opinion, that since no longer available online should be considered as not a valid source. I for example happen to have a copy of Knowlton's 1949 Standard Handbook for Electrical Engineers as we;; as copies of a number of 1960s vintage textbooks, which I refer to extensively. Does that mean that if I cite these books in articles in these sources, which later no longer becomes available from me for any particular reason that references in these no longer a valid citations/ What happens to all the broken links in articles for papers, articles and other lesser publications that later only become available by purchasing? If the answer to these questions are that sources need to be only generally available, Wikipedia has a huge problem that greatly threatens the quality of some, in some cases, inherently high quality articles.Cblambert (talk) 05:27, 19 January 2017 (UTC) An IEEE Explore search shows Kay Hameyer figuring between 1994 amd 2016 in 159 conference publications, 126 journal & magazine articles and in 5 early access articles. 94 of these documents being published by the IEEE Transactions on Magnetics.Cblambert (talk) 23:50, 20 January 2017 (UTC)

The standard for scholarly citation is publication in a peer-reviewed professional journal with a reputation for accuracy. "Hameyer's 2001 course document" fails on all counts. You might want to review WP:RS, or better yet, WP:MEDRS. Sbalfour (talk) 02:10, 28 November 2017 (UTC)

I agree. Even if Hameyer is an authority, there is no guarantee that he was rigorous in his course notes. He might have made approximations or simplifications appropriate for his audience. Part of the information might have been verbal and not part of the notes. Yes, I agree that Hameyer is not a RS, although it seams that the standard has fallen as more content finds its way on to the internet. Constant314 (talk) 04:52, 28 November 2017 (UTC)

Notes / structure

In the current article, we can't see the forest for the trees. Most of the definitional type equations were (and should be again) annotations in the circuit diagrams. That'd leave the content of the article essentially 4 (or 5) diagrams. Then we need to write the article around them. I propose the following restructure of the article:

Lead

---

Definitions - things we'd find in an engineering specification of a transformer or other device

What goes here aren't equations, but descriptions of the concepts and relationships. In an engineering spec, they'd eventually be assigned some number derived from measurement. The concepts tell us what we'd like to assess.

• Coupling coefficient & coupling factor
• Leakage flux
• Leakage inductance
• Leakage inductance factor
• etc

---

Nonideal linear two-winding transformers

• Transformer operation (meta description - there shouldn't be much math here)
  • Magnetic and electric circuits
  • Self-Inductance and mutual inductance

Next section is in two parts: first are definitions of measured or measurable quantities (since we can't actually measure things like leakage flux or leakage inductance). These would be in instructions to a lab tech and come back as a set of numbers on a datasheet. These are contextual constants (since once measured, they can't change), so may never appear on the left-hand side of an assignment. The second part is derived quantities and the mathematics (probably vector & integral calculus) to obtain them. For clarity in the article, derived and measured quantities could/should be distinguished by different fonts or colors. It would help here if the relational equality operator '$=$' were distinguished from the assignment operator '$:=$', the transitive operator '$\rightarrow$', the 'is defined as' operator '$:\Leftrightarrow$', the 'implies' operator '$\Rightarrow$', the 'may be inferred from' operator '$\Leftarrow$' and in some cases the congruence operator '$\cong$ '.

• Inductance models
  • Terminal models
    • Open circuit
    • Open+short circuit
  • Duality models
• Equivalent circuits w/annotations (most of the existing article would go in this section)
• Advanced theory (operational factors influencing magnetic reluctance of core)
  • Eddy currents
  • Soft saturation
• Reducing and increasing leakage inductance
  • Concentric windings
  • bifilar windings
  • interleaved layers
  • doped windings
  • air-gapped cores
  • toroidal cores

---

Other transformers and devices

• air-core transformers (explanation of magnetic circuit, inductance and leakage inductance in absence of magcore)
• Multiwinding transformers
• Nonlinear transformers (maybe for separate article; leakage inductance for these is a hyperbolic topic)
• Inductors (leakage inductance just becomes part of self-inductance)
• Induction motors and generators
  • Synchronous & asynchronous motors (i.e. inductive vs capacitative reactance and losses)
• Leakage inductance devices (ones designed to exploit leakage inductance)

Sbalfour (talk) 15:40, 29 November 2017 (UTC)

Core of the article

What this article is about is simple. There's only three things on the output side: leakage inductance, and two ratios, coupling factor and leakage factor. We might need to distinguish primary and secondary leakage inductance in some of the math. There are only 4 things on the input side, which we measure: voltage, current, DCR and winding ratio. Again we might need to distinguish these for primary and secondary. Everything else is cruft. So, we need three definitions, one for leakage and two for the ratios (these last are one-liners). We describe a procedure for measurement (put in a sidebox), do some math, and at the bottom, three (possibly 4) equations whose left-hand sides are leakage inductance, coupling factor and leakage factor, and right-hand sides are functions of the measured quantities. And that's it. 3 (maybe 4) equations, no more. Anything else, goes in a footnote, sidebox, link to other article, etc.

That's the core. The core needs context, so we pack it on, above and below, but we keep it out of the core.

Sbalfour (talk) 00:46, 1 December 2017 (UTC)

Symbol notation conventions

There are several confounding "styles" of symbol notation in the article. For example, designating various inductances on the primary side:

• $L_{P}$ primary self-inductance
• $L_{M}$ magnetizing inductance referred to the primary
• $L_{sc}^{pri}$ primary short-circuit inductance
• $L_{S}^{\sigma '}$ leakage inductance from secondary referred to the primary (formerly; deleted from article but still used in diagram)

There are only 5 referred to quantities, yet it seems necessary to denote two of them with super- and sub- scripts? And as shown, two more with triple super- sub- scripts?? We could easily designate the 5 quantities P, S, M, l1, and l2. Their semantics are very clear even though I've not defined them here. We don't need L to tell the reader these are inductances - everything in the article is an inductance. If we need to reference reactance, it could be written $X_{P}$, etc. We also have the components of $L_{P}$: $_{M}$ and $\sigma$, one designated by a subscript $L_{M}$ and the other by a superscript $L_{P}^{\sigma }$. In addition, $M$ and $L$ are both used to represent inductance; the logical $L_{M}$ for mutual inductance is used for something else, doubly confounding. $L_{M}$ (and $L_{M2}$) don't have the same kind of existence as $L_{P}$ (and $L_{S})$; they're placeholders for a mathematical computation. They could be represented like this $L_{p\leftarrow M}$ or $L_{p/M}$ or maybe $L_{p\subset M}$. That frees $L_{M}$ to represent mutual inductance. The relationship of these symbols could be denoted clearly by using the identity $L_{M}$ = $L_{p\leftarrow M}\circ L_{s\leftarrow M}$. "Short-circuit inductance" ($L_{sc}^{pri}$) is often referred to inexactly as leakage inductance; it's almost an alternate definition. $L_{P}^{\sigma '}$ might be a plausable way to represent it. The prime isn't very prominent, so maybe $L_{P}^{\sigma +}$ is more noticeable.

Sbalfour (talk) 20:50, 3 December 2017 (UTC)

Inductive relationships, independent variables and equations

Starting with the first three equation 2.1 and two following unnumbered equations,

$L_{P}=L_{P}^{\sigma }+L_{M}$

$L_{P}^{\sigma }=L_{P}\cdot {(1-k)}$

$L_{M}=L_{P}\cdot k$

like any mathematician, I substituted the value of k from equation 4.3 below into the equations expecting to elucidate some fundamental relation:

$L_{P}^{\sigma }=L_{P}\cdot {(1-{\frac {M}{\sqrt {L_{P}\cdot L_{S}}}})}$

$L_{M}=L_{P}\cdot {\frac {M}{\sqrt {L_{P}\cdot L_{S}}}}$

$\rightarrow L_{P}=L_{P}\cdot {(1-{\frac {M}{\sqrt {L_{P}\cdot L_{S}}}})}+L_{P}\cdot {\frac {M}{\sqrt {L_{P}\cdot L_{S}}}}$

$\rightarrow L_{P}=L_{P}-M\cdot {\sqrt {\frac {L_{P}}{L_{S}}}}+M\cdot {\sqrt {\frac {L_{P}}{L_{S}}}}$

$\rightarrow L_{P}=L_{P}+{\sqrt {\frac {L_{P}}{L_{S}}}}\cdot (-M+M)$

$\rightarrow L_{P}=L_{P}+0$

$\rightarrow L_{P}=L_{P}$

After that monumental effort, the result is a tautology. The reason is two-fold: the third equation above isn't independent- it follows directly from the other two. And k itself is twice substituted into an equation defining $L_{P}$, which is a constituent part of the definition of $k$ itself. $k$ is not actually an independent variable here - it's an alternate name, a shorthand for <expr>. The relationship is thus: $k\cong$<expr>

There are 20 equations in the article not counting sec. 5. There are as I can see, only 5 independent equations (defining 5 independent quantities): $L_{P}$, $L_{S}$, $L_{P}^{\sigma }$, $L_{S}^{\sigma }$, and $M$. There is also one inductive relationship not defined, or derivable from any of those, which is missing from the presentation. The rest of the equations are just shuffling between representations; no new relationships are thereby established. It's cruft - those who have or need different inputs to the model can do the math. This article is about elucidation of relationships, not representations. I'm going to shrink it down dramatically to just a set of independent equations/variables, in terms of the inputs to the inductive transformer model.

It's a total waste of effort. I wouldn't trust an equation in WP to convert from Fahrenheit to Celsius. Even if you sweat out the maths typesetting and make it match some credible reference, WP:Randy from Boise will shortly be along and put his own unique stamp on it. Delete all the equations and just explain it in general terms; anyone who really needs to know quantitatively what's going on, should pay for a professionally edited textbook. --Wtshymanski (talk) 00:58, 4 December 2017 (UTC)

Hmmm... I'd not suspect you'd want to trim everything. Some editor will come along an drop it back in, because "the article didn't have it". I'm already sort of down to the definitions... there's no conversion math, except one equation, and I'll delete it forthwith. I hated sifting through all that math, to make sure I didn't omit anything. It was cruft... (Stay tuned.) I was imagining you sitting in the background laughing your @ss off while I sweated bullets. Cheers, Sbalfour (talk) 04:44, 4 December 2017 (UTC)

Article rewritten; archive?

The article has essentially been rewritten, and talk page discussion for all sections above Notes / Structure is now irrelevant and closed. I'm considering archiving all dead topics so editors have a clear picture of active topics. I'm aware, though that another editor has been accused of vandalism for using [hide] templates and archiving to conceal active topics. That is not my intention; the content referred to in dead topics no longer exists. Yes, it can be restored, with necessary accompanying citations, and an editor so doing can start a new topic for the justification. However, given the new structure of the article, I just don't think that's going to happen. Sbalfour (talk) 19:27, 4 December 2017 (UTC)

I would not object to archiving. Constant314 (talk) 01:16, 6 December 2017 (UTC)

And I would like to stop seeing those reference to Hameyer at the end. Not only is it not a WP:RS it is not available.Constant314 (talk) 12:50, 6 December 2017 (UTC)

Point taken - I, too, object to the Hameyer sources. They now belong to deleted sections that are reproduced only here, on the talk page. I can confine them to the referencing sections, so that when archiving is complete, they'll be off the page. It's perhaps not fair to vanish them altogether, but they CAN'T go back into the article. Sbalfour (talk) 21:16, 6 December 2017 (UTC)

The definition of "a".

This is from Brenner and Javid. Do what you want with it.

The upper circuit has an arbitrary parameter a which is the turns ratio of the ideal transformer in the circuit. The circuit is equivalent to the actual non-ideal transformer. It works no matter what value you choose for a. If you choose a such that a² = L₁/L₂, then the top circuit reduces to the bottom circuit. L₁ and L₂ are the open circuit actual terminal inductance for each side of the transformer. The important point is that a is not the turns ratio, although it is close and often said to be the turns ratio but it the square root of the inductance ratio and reduces to the turns ratio as the leakage inductance reduces to zero. Constant314 (talk) 01:13, 6 December 2017 (UTC)

Hmmmm...I'm aware of this little anomaly. The difference between deterministic 'a' in an ideal transformer and 'a' as derived by measured quantities in a real transformer, is due to inexactitudes in measurement. The measured quantities include a little of this and that, so that 'a' does too. I've got a real transformer I use to check my sanity, and it's a pud*ucking example of why things are so hard. Even if I did count the turns, which I'm not going to do, it won't be the 'a' which makes everything else come out 'pretty close'. Sbalfour (talk) 21:29, 6 December 2017 (UTC)

P.S. Thanks, and stick around. I need some help on this article. It's been ~50 years since I worked with this stuff.Sbalfour (talk) 21:35, 6 December 2017 (UTC)

The equation $L_{P}=a^{2}\cdot L_{S}$ used to be in the article, it was sourced by B&J with a footnote comment almost like yours. It is only reliable if the leakage inductances are small (less than a few percent) and proportional to the self-inductances of the the coils. Fortunately, that is the case much of the time. It doesn't work very well at all for my bench transformer, because it has large and assymmetrical leakage losses (I designed it that way). So I deleted the equation from the article. I don't know that there's any way to indirectly determine the physical turns ratio in a real transformer. Transformers aren't spec'ed with turns ratios, but with voltage ratios. These aren't open-circuit ratios - they're voltages at rated load and won't correspond to the turns ratio. So, maybe it matters that we spell out some way of measuring $a$. The transformer model of the article postulates '$a$', as if we're told it. But note that we haven't spelled out how to measure $k$ or $\sigma$, either. Sbalfour (talk) 00:12, 8 December 2017 (UTC)

Short-circuit inductance

This subsection has been incorporated from what was originally an article (really little more than a dictionary definition) of the same name. There was originally a partial derivation of short-circuit inductance in the Leakage inductance article as part of a section titled abstrusely, Inductive leakage factor and inductance. It had a bunch of abstract flux equations rather lacking context, and no discussion of what role short-circuit inductance plays in the measurement of a transformer. I was unable, based on that, to incorporate short-circuit inductance into the redrafted article at that time.

Short-circuit inductance is one of two complementary methodologies, which together are called the "terminal measurement model". In contrast is the "flux duality model", which is based on assessment of flux paths in a window of the core where the windings pass through. This model ignores terminal measurements. The two models naturally give somewhat differing results, on account of incorporating different kinds of losses, and measurement and estimation errors.

For derivation of Leakage inductance, there are only four relevant measurable quantities: open- and short-circuit primary and secondary inductances (or alternatively voltages and currents). Both sets of measurements are required, and both are part of standard laboratory procedure (I must state here that naively shunting across the terminals of a transformer and switching it on with the hope of measuring something, is extremely hazardous and likely to result in destruction of the transformer. This is not what is done in the laboratory.)

Justification for the validity of short-circuit measurements (that is, what do they actually mean) unfortunately relies on flux-path analysis, hence the original cryptic equations.

I do not think either laboratory procedures or magnetic circuit analysis (w/integral calculus) to be meaningful in the context of the article, since these confound the article's accessibility. Some more intuitive notion of what sounds like a dubious procedure is needed, which I have yet to formulate.

Sbalfour (talk) 17:05, 8 December 2017 (UTC)

I agree to move short-circuit inductance to this article. But generally, those who prefer theoretical writing don't like this being mentioned in the same article. That's because the short-circuit inductance is the measurement value, while the other parameters are theoretical amount. Therefore I thought that it would be better to make it independent and made another article. Originally "short-circuit inductance" was in this article. Please refer to the past description as well. (Leakage_inductance&oldid=401166149) Also, measurement of short-circuit inductance is simple, only measuring with LCR meter. It does not measure with actual specification power. Leakage inductance has been repeatedly rewritten largely from various standpoints. The most practical description is to describe only the results formula in the viewpoint of the electronics circuit designer. Then supplement the theory of the background according to the Electrical engineering textbook. Although the academic theoretical description method has a method described from the engineering viewpoint of the transformer and another from the magnetism viewpoint, and the previous description was biased to the magnetism viewpoint. Despite describing from either perspective the results are the same, it is very interesting matter for me. And why Europe like the "inductive coupling factor" and supports only positive values, whereas the textbook of engineering in other countries' transformer engineers like the "coupling coefficient" and also supports the positive and negative values. I understood the meaning at same time. --Discharger1016 (talk) 22:26, 8 December 2017 (UTC)

Open-circuit measurement, short-circuit measurement, direct current measurement of resistance, tank-circuit measurement, frequency response measurement and others are all complementary methodologies, some or all of which play a role in defining the specifications of a transformer including leakage inductance. Real world measurement is a complex and error-prone undertaking, which is not in most cases a topic of encyclopedia scholarly articles. The article as it existed when I found it was nearly inaccessible. In particular, algebra and higher math scares people off. Leakage inductance is an ephemeral topic - it can't be seen or measured directly. Bringing that into the understanding of a high school graduate without substantive scientific background (the average American) is the challenge. Short-circuit measurement is worth a paragraph, because as you note, stick an LCR meter on the terminals, and you're done (however, if the little battery can't magnetize the core, your measurements will be meaningless). Encyclopedia Britannica doesn't have an article on Leakage inductance; it's part, if anywhere, of the article on transformers. Maybe we should cop a clue - it's not possible actually to write a feature-length article on it, or short-circuit inductance. That's why I brought them together. Sbalfour (talk) 19:47, 9 December 2017 (UTC)

Impedance

Regarding in Notes section: This kind of "resistance" in an AC circuit is a related quantity properly called inductive reactance, or more generally, impedance.

Impedance Z of a resistance in series with an inductive reactance, such as in a transformer winding, is equal to ${\sqrt {R^{2}+X^{2}}}$, where R is resistance and X in inductive reactance!Cblambert (talk) 02:12, 7 August 2018 (UTC)

Kay Hameyer's research while affiliated with RWTH Aachen University and other places

Kay Hameyer, Dr.-Ing. Dr. h. c. dr hab. - Research contributions (367 Publications)

IEEExplore search for Hameyer show 318 documents Source: https://ieeexplore.ieee.org/search/searchresult.jsp?newsearch=true&queryText=hameyer

Kay Hameyer (Senior MIEEE, Fellow IET) received the M.Sc. degree in electrical engineering from the University of Hannover, Germany. He received the Ph.D. degree from University of Technology Berlin, Germany. After his university studies he worked with the Robert Bosch GmbH in Stuttgart, Germany, as a design engineer for permanent magnet servo motors and automotive board net components. In 1988 he became a member of the staff at the University of Technology Berlin, Germany. From November to December 1992 he was a visiting professor at the COPPE Universidade Federal do Rio de Janeiro, Brazil, teaching electrical machine design. In the frame of collaboration with the TU Berlin, he was in June 1993 a visiting professor at the Universite de Batna, Algeria. Beginning in 1993 he was a scientific consultant working on several industrial projects. He was a guest professor at the University of Maribor in Slovenia, the Korean University of Technology (KUT) in South-Korea. Currently he is guest professor at the University of Southampton, UK in the department of electrical energy. 2004 Dr. Hameyer was awarded his Dr. habil. from the faculty of Electrical Engineering of the Technical University of Poznan in Poland and was awarded the title of Dr. h.c. from the faculty of Electrical Engineering of the Technical University of Cluj Napoca in Romania. Until February 2004 Dr. Hameyer was a full professor for Numerical Field Computations and Electrical Machines with the K.U.Leuven in Belgium. Currently Dr. Hameyer is the director of the Institute of Electrical Machines and holder of the chair Electromagnetic Energy Conversion of the RWTH Aachen University in Germany (http://www.iem.rwth-aachen.de/). Next to the directorship of the Institute of Electrical Machines, Dr. Hameyer is the dean of the faculty of electrical engineering and information technology of RWTH Aachen University. Currently he is elected member and evaluator of the German Research Foundation (DFG). In 2007 Dr. Hameyer and his group organized the 16th International Conference on the Computation of Electromagnetic Fields COMPUMAG 2007 in Aachen, Germany. His research interests are numerical field computation, the design and control of electrical machines, in particular permanent magnet excited machines, induction machines and numerical optimisation strategies. Since several years Dr. Hameyer's work is concerned with the magnetic levitation for drive systems. Dr. Hameyer is author of more than 180 journal publications, more than 350 international conference publications and author of 4 books.

Dr. Hameyer is an elected member of the board of the International Compumag Society, member of the German VDE, a senior member of the IEEE, a Fellow of the IET and a founding member of the executive team of the IET Professional Network Electromagnetics.

Biography source: See link at http://info-optim.ro/hameyer.phpCblambert (talk) 15:34, 8 August 2018 (UTC)

Breath of fresh air

For a technical article (try magnetic reactance for the counter-example), this article is actually invigorating! It's free of jargon, differential, integral or algebraic math , wacky symbols like $\int ,\Sigma ,{\sqrt {,}}dy/dx$ (yeh, I fudged and left in a couple of sqrts... I'm thinking about that), discussions of magnetic circuits (most people are comfortable with electric circuits, but not magnetic ones) and vector fields, cryptic circuit diagrams and symbol names, and concepts that aren't defined in the article. The phraseology is a bit colloquial, but I don't think the technical accuracy is affected much. Sbalfour (talk) 04:24, 5 December 2017 (UTC)

'most people are comfortable with electric circuits, but not magnetic one'??!! Really?!. I call this a heroic assumption.Cblambert (talk) 19:43, 10 August 2018 (UTC)

Unbelievable! Someone purporting to have a strong interest in the Leakage inductance article suggesting that magnetism is not needed to explain Leakage inductance. There is something very, very wrong with this notion. I can't believe that a major contributor to this article would be willing to put his thumb on the balance to bias things in favor of electric aspects to the disadvantage of magnetism aspects!!?? Just so we are clear, EE301 – MAGNETISM AND TRANSFORMERS: "A transformer is a magnetically coupled circuit, whose operation is governed by Faraday’s Law. Right? Cblambert (talk) 22:49, 10 August 2018 (UTC)

Refined inductive linkage factor removed

Rubbish all of it -- single source, unreliable source & A major contributor to this section appears to have a close connection with its subject. Cblambert (talk) 20:37, 12 August 2018 (UTC)

Turns ratio II

AESO Tranaformer Modelling Guide makes 37 mentions the term 'turns ratio', the second mention of which says "Therefore, a transformer is typically described by its rated voltage $V_{H}$ and $V_{X}$, which gives both the limits and the turns ratio."

The above section The_definition of "a" says "I don't know that there's any way to indirectly determine the physical turns ratio in a real transformer. Transformers aren't spec'ed with turns ratios, but with voltage ratios. These aren't open-circuit ratios - they're voltages at rated load and won't correspond to the turns ratio.

This is partly misleading, partly wrong.

Partly misleading because the term 'turns ratio' is often used.

Partly wrong because rated voltage is often based on no-load conditions whereby one starts with rated voltage (no-load voltage). This is associated with the voltage regulation of constant-potential transformer which Knowlton 1949 says "is the change in secondary voltage, expressed in per cent of rated secondary voltage, which occurs when the rated kVA output at a specified power factor is reduced to zero, with the primary impressed terminal voltage maintained constant."

Some even say "Rated voltage, secondary: The voltage which is generated for the transformer’s secondary line terminals with or without load (depending on the standard)."Cblambert (talk) 01:05, 9 August 2018 (UTC)

Knowlton further says:

• The ratio of a transformer is the turn ratio of the tranformer, unless otherwise specified.
• The voltage ratio of a transformer is the ratio of the rms primary terminal voltage to the rms secondary terminal voltage, under specified conditions of load.
• The turn ratio of a trasformer is thr ratio of the number of turns of high-voltage winding to that in the low-voltage winding.

Note: in the case of a constant-potential transformer having taps for changing its voltage ratio, the turn ratio is based on the number of turns corresponding to the normal rated voltage of the respective windings, unless otherwise specified.

The true ratio of a current or a potential transformer is the ratio of rms primary current or voltage as the case may be, to the secondary current or voltage under specified conditions.

The marked ratio of a current or a potential transformer is the ratio of the primary current or voltage as the case may be, tothe secondary current or voltage, as given on the rating plate.

This is complicated by the fact that terminology is crucial for modelling of transformers for power system analysis purposes.Cblambert (talk) 01:42, 9 August 2018 (UTC)

AESO Transformer Modelling Guide says

• "When the adjusted turns ratio N is equal to the ratio of the system-rated voltages, the ratio is called nominal, and the transformer is omitted from the single-line diagram in a per-unit system. When the adjusted turns ratio N is not equal to the ratio of the system rated voltages, it is said the transformer has an off-nominal turns ratio. It should be noted that the off-nominal turns ratio is a definition used for modelling, and it is not to be confused with the physical transformer nominal ratio that may appear on the nameplate of the transformer. The off-nominal turns ratio can be a real number or a complex number. If is is a complex numer, the transformer is called a phase-shifting transformer. In such a case, the voltages on the two sides of the transformer differ in phase as well as in magnitude."Cblambert (talk) 04:20, 9 August 2018 (UTC)

All to say that as Saarbafi says "$E_{H}/E_{X}=N_{H}/N_{X}=I_{X}/I_{H}$ This is the basic equation for all types of transformers" (Empahis added). It is utterly useless to discuss Transformer and Leakage inductance articles unless one is 100% clear about the symbiotic dependence of turns ratio with winding voltages and currents.Cblambert (talk) 01:00, 10 August 2018 (UTC)

According to Megger's Ohlen 2010,

• §2.2 Definitions, §2.2.1 Turn ratio and voltage ratio: The turn ratio of a transformer is the ratio of the number of turns in a higher voltage winding to that in a lower voltage winding. The voltage ratio of a transformer is the ratio of the rms terminal voltage of a higher voltage winding to the rms terminal voltage of a lower voltage winding under specified conditions of load. For all practical purposes, when the transformer is on open circuit, its voltage and turns ratios may be considered equal.
• §3.4 Tolerances for ratio, §3.4.2 IEEE Std 62-1995 (field testing): The turn ratio tolerance should be within 0.5% of the nameplate specification for all windings.

(Italics emphasis added) Cblambert (talk) 20:59, 22 August 2018 (UTC)

References

Saarbafi, Karim; Mclean, Pamela (July 8, 2014). "AESO Transformer Modelling Guide" (PDF). Teshmont Consultants LP for Alberta Electric System Operator (AESO), Calgary, Alberta, Canada. pp. 304 pages. Retrieved August 6, 2018. {{cite web}}: Invalid |ref=harv (help)CS1 maint: year (link)Cblambert (talk) 01:00, 10 August 2018 (UTC)

Ohlen, Matz (18 October 2010). "A Guide to Transformer Ratio Measurements" (PDF). Täby, Sweden. {{cite web}}: Invalid |ref=harv (help)CS1 maint: year (link)Cblambert (talk) 20:59, 22 August 2018 (UTC)