Talk:Magnetic circuit

Schematics?

Are there symbols for drawing schematics of magnetic circuits? — Omegatron 14:50, 29 November 2006 (UTC)

There is a magnetic circuit drawn in the section "Circuit Laws" but it does not seem to be mentioned in the text and doesn't have anything useful to say. For example there are 5 flux arrows labelled Φ1 to Φ5. But this is a series magnetic circuit so all 5 values are identical! There are 5 lines called A1 to A5 which make most sense as areas. This drawing would be more useful if Φ values were converted to B values (flux density). Then we would have Flux Density times Area = Flux. B1 x A1 = B2 x A2 = B3 x A3 = B4 x A4 = B5 x A5 87.113.149.155 (talk) 21:56, 23 June 2013 (UTC)LOG

Someone needs to actually DRAW something. — Preceding unsigned comment added by 99.225.225.1 (talk) 21:14, 23 February 2015 (UTC)

Yes, if I get the time I could probably draw something up. Magnetic circuits are not normally as complicated as electric circuits. They normally consist of a single loop containing a source of flux (coil or permanent magnet) and a single reluctance. --Chetvorno^TALK 21:40, 23 February 2015 (UTC)

Reluctance: R or S?

If we're making analogies to electric circuits, we probably shouldn't use R for both reluctance and resistance on the same page. The Reluctance article uses S for reluctance, but I don't know if this is in common use elsewhere. Is it? We don't want to make up our own terminology unless absolutely necessary. — Omegatron 15:15, 29 November 2006 (UTC)

• All of my books use a fancy ${\mathfrak {R}}$ like the Reluctance article.-W0lfie (talk) 16:49, 5 March 2009 (UTC)

Merge proposal

I am proposing merging magnetic reluctance, magnetic complex reluctance,magnetic capacitance, and magnetic capacitivity into this article. Together they would make an ok start to magnetic circuits; apart they cannot carry their own weight. Eventually these articles will make great sub-articles to the main page of magnetic circuits; but eventually is not now.

Unless someone objects I will probably do the merge myself. TStein (talk) 03:25, 11 May 2009 (UTC)

I think magnetic reluctance, magnetic complex reluctance,magnetic capacitance, and magnetic capacitivity should be merged, but I'm not sure if they should be merged into this article. They could be merged into magnetic reluctance, which may be an important enough concept to stand on it's own, or they could be merged into magnetic permeability. It seems to me that readers who are just looking for a definition of these widely used electromagnetic quantities shouldn't have to plow through the magnetic circuit article to find them. --Chetvorno^TALK 15:50, 24 May 2009 (UTC)

I agree with Chetvorno - it was a relief to me to find the "reluctance" definition directly. —Preceding unsigned comment added by Shumpi (talk • contribs) 17:35, 11 June 2009 (UTC)

• "Reluctance" must be by analogy with "Electrical resistance"!--Angstorm (talk) 11:31, 5 July 2009 (UTC)

Electrical circuit analogy

Isn't there a mistake in the heading of the table comparing the two types. It seems the magnetic header is above the electrical proporties —Preceding unsigned comment added by 129.31.80.191 (talk) 14:18, 24 May 2009 (UTC)

Yes. However the table also just seems plain ol' broken in several places, so I'm reluctant to just switch the headers around. I'm sorely tempted to just delete it and wait for someone to put it back in more accurate form, but I'll restrain myself and let someone more expert sort it out. --207.173.201.99 (talk) 16:57, 11 June 2009 (UTC)

Thanks 129.31.80.191 for pointing out the mistake with the headers. It was easy enough to fix. Somehow I missed it until 207.173.201.99 comments. What else is broken about it besides the fact that the data needs to be justified better?

I created the table as a quick summary of the material and in order to better show the analogy together in one place. It is not perfect. I believe, though, that it is better to have it even in its imperfect state then not to have it. Deleting it will not help fix it nor to make the article any better. TStein (talk) 21:49, 11 June 2009 (UTC)

Template for magnetic circuit articles (and their "electric" analogues)

I am seriously seeing the need for a navigation template for these things. The information right now seems to appear really scattered. Also, there does not seem to be any clear justification for merging all these materials. Separate articles are preferable. The use of navigation template would facilitate transparency to the material. I see no need for this to be approved. As I soon finish working up some of the other articles to maintain consistency, then I will do something about the navigation template.Kmarinas86 ^(6sin8karma) 04:13, 23 June 2009 (UTC)

Magnetic circuits vs. Cap-Gyrator model

We got a mess to clean up. There are two different systems of magnetic circuits: the common one, and the gyrator capacitor model [1]. They are different--different variables, different analogies between physical quantities and circuit variables. But we've got a single navbox that unifies them all. Ack!!!

I think we should have just two articles--one on magnetic circuits and one on the cap-gyrator model. An alternative would be to have two headings in the navbox to show that they are two different systems. If you mix them up you get nonphysical stuff happening--energy sources, etc.

I'm going to go ahead and delete the navbox from the main articles, because I think sending people off to incompatible components is more harm than help. -Ccrrccrr (talk) 01:31, 25 July 2009 (UTC)

Two navboxes are needed then. I am not qualified to know which goes where, so if someone could politely inform me which goes where, I can see if I can sort it out. If not, I think someone else should do it.Kmarinas86 ^(6sin8karma) 23:24, 25 July 2009 (UTC)

I can try to help, but the problem is that most of the articles are in really bad shape, so it's not always easy to tell what's going on. Some contain no English language references, so it's not even clear that the terms exist in English, prior to Wikipedia. So it's hard to establish what would be the "correct" terminology. I'm wondering whether we should delete the individual articles, and just have two articles, one for each model type, with the rest being redirects to these two. The Gyrator-Capacitor model could start as a stub linking to the paper I linked above.

As a start:

• Magnetic circuits use MMF, Magnetic flux, reluctance, and complex reluctance.
• The magnetic tension force article is not anything related. I think some of these articles used that term as a mistranslation, perhaps of MMF.
• Permeablilty is not a magnetic circuit concept, even though it's related. Mag ckts are distinguished from other magnetic field calculations in that they are in terms of reluctance rather than permeability.
• The use of z for magnetic reluctance should be removed from the navbox, as that's non-stantdard.
• All the stuff with an M subscript is from the gyrator capacitor model. All of those articles are really confusing and full of bizarre terminology that probably originated as mistranslations. So I vote for making them all redirect to a new gyrator capacitor model page, perhaps keeping a disambigation header on them.

-Ccrrccrr (talk) 02:57, 27 July 2009 (UTC)

Limitations of the analogy

Recently, some changes were made to the third bullet point of the "Limitations of the analogy" section, pointing out that electrical circuits can have nonlinearity and hysteresis like magnetic circuits. With respect, this is not relevant to the article. This article specifically compares a magnetic circuit to a linear, resistive electric circuit, with only voltage sources and resistances, that obeys Ohm's law. It is based on the similarity between Ohm's law and Hopkinson's law. Typical resistive electric circuits obey Ohm's law to accuracies of 4 to 6 significant figures. Typical magnetic circuits obey Hopkinson's "law" only very approximately, with variations of the flux due to nonlinearity of 50% or more, and residual flux of 20% or more left in the circuit after the "sources" are turned off. --Chetvorno^TALK 19:40, 12 May 2012 (UTC)

Quoting from the above "This article specifically compares a magnetic circuit to a linear, resistive electric circuit." That may be true for some revision of the article, but I believe that would be a poor choice. Magnetic circuit analysis is widely used for nonlinear magnetic circuits. So it would be a mistake to limit an article under this title to that narrow scope. Here is just one of many articles you can find on google scholar on nonlinear magnetic circuits.

Takahashi, N.; Nakata, T.; Uchiyama, N.; , "Optimal design method of 3-D nonlinear magnetic circuit by using magnetization integral equation method," Magnetics, IEEE Transactions on , vol.25, no.5, pp.4144-4146, Sep 1989 doi: 10.1109/20.42549 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=42549&isnumber=1621

Limiting the scope of this article to linear magnetic circuits would be like limiting the scope of the electrical circuit article to linear circuits. If it would be useful, we could create a new article titled linear magnetic circuit, but that would be a bad idea for the reason you point out above--it's very often a poor approximation. On the other hand, if you want to limit the scope of the discussion to linear reluctances, we do have a magnetic reluctance article which might be a more appropriate place for that.

Ccrrccrr (talk) 22:11, 24 May 2012 (UTC)

Well, I agree. I don't like the way this article is written. The whole article tries to define "magnetic circuit" by the very limited analogy between a magnetic circuit and an electric circuit. The intro says: "The concept of a magnetic circuit exploits a one-to-one correspondence between the equations of the magnetic field in an unsaturated ferromagnetic material to that of an electrical circuit." As long as that's the definition we're limited to linear circuits. That's why I added the section "limitations of the analogy". I'd suggest taking that sentence out of the intro, along with the other content on the electric-magnetic circuit analogy, and putting it in a subsection entitled something like "Analogy with electric circuits". Then the rest of the article can cover the nonlinear and other aspects that don't fit that analogy, which you so rightly point out should be included. --Chetvorno^TALK 22:40, 24 May 2012 (UTC)

I think the limitations are partly a result of that definition. What happens when a magnetic circuit is defined differently such that you can determine/specify energy outflows from say interactions with ferromagnetic materials? Then you have power dissipated in 'reluctances'. TEK1 (talk) 19:56, 15 October 2023 (UTC)

Magnetomotance?

Just as the poorly-named 'electromotive force' has been renamed 'electromotance' (EMF), the 'magnetomotive force', which is not a force, should be renamed magnetomotance.TAB (talk) 18:47, 11 June 2012 (UTC)

I agree. --Chetvorno^TALK 19:14, 11 June 2012 (UTC)

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Units for Reluctance and Permeance should match

At the moment we have:

"R is the reluctance [...] in [...] (a unit that is equivalent to turns per henry)."

and

"P = 1/R [...] Its SI derived unit is the henry (the same as the unit of inductance, although the two concepts are distinct)."

If the unit for R is turns/henry, then the unit for P is henry/turn, and is thus not confused with plain henry.

Doubtless confusion on this point arises from SI's classification of units for phenomena such as angle and turn as "optional", and by attempting to cover them with the "special unit 1" (as distinct from the number 1). Treating "special 1" as though it's number 1 (and thus droppable) leads to apparent equivalence of incompatible quantities when attempting to perform dimensional analysis, or, as here, just trying to convey to users the nature of a quantity.

My suggestion would be to at least provide units for R and P that are consistent, and to choose the option to include "turns" in the units so as to make clear the distinction from units that lack turns, and to allow the units to work in dimensional analysis. Gwideman (talk) 12:59, 19 June 2016 (UTC)

Circuit Laws section is profoundly misleading

At the moment, the Circuit Laws section is illustrated by a figure which is misleading in itself, and very misleading relative to the narrative it accompanies.

First off, the figure shows a magnetic circuit in which fluxes phi1, phi2...phi5 should all be equal, yet they are represented by different numbers of arrows (lines). Either this is wrong, or these arrows, though labeled as fluxes, are confusingly not intended to represent lines of flux.

Second, the narrative states the analog to Kirchoff's current law, spelling out phi1 + phi2.. = 0. Clearly this does not correspond to the diagram where phi1, phi2... do not all enter a particular node (and don't sum to zero... indeed they are all equal).

In short, it's not clear the intended purpose of the figure, and as it stands, it strongly detracts from the narrative. Gwideman (talk) 23:17, 20 June 2016 (UTC)

Merge of magnetomotive force

The edit summary proposing the merge of magnetomotive force here reads "just a definition, not an article". Well, first of all, many readers look up basic concepts on Wikipedia just to get the definition. We should not unnecessarily make them plough through another article to find it. Secondly magnetomotive force is an important parameter, maybe on the same level as magnetic flux so should have its own article, just as electromotive force and electric current have their own pages. Finally, I am sure the article is capable of being expanded significantly. William Gilbert (astronomer) could be mentioned just to start off with and I'd like to see more on the history of the term - when it first came into use, how it came to be called a force etc. When elastance, a rather more obscure parameter, was put up for deletion I thought that it was going to be a dead duck for sure, but with a bit of effort I was able to make this edit. SpinningSpark 18:53, 14 March 2018 (UTC)

Agree with the above. --Chetvorno^TALK 21:59, 14 March 2018 (UTC)

Agree TStein (talk) 18:31, 26 April 2018 (UTC)

History section

I have removed the history section from the article which I think is extremely problematic. The original text read,

References

Problems include,

• This mostly does not give the history of magnetic circuits per se, just the origin of certain terms
• The text is a pure copypaste from the magnetic reluctance article. No need to have it repeated here as well causing a maintenance problem
• It is entirely referenced to primary sources and a lot of it is dubious.
  • I'm confident that Heaviside/Reluctance is correct but that can sensibly be left to the reluctance article
  • Joule/magnetic resistance - 1884 sounds much too late for the priority of this idea and is contradicted by what is said about Rowland
  • Bosanguet/mmf is definitely incorrect. This was Rowland again - see the secondary sources I added to the magnetomotive force article on this: Rowland (1880) v. Bosanquet (1883)
  • Rowland/Ohm's law contradicts what the article said earlier (Hopkinson/Ohm's law). I've retained the Rowland ref but moved it earlier where it can be put in context with Hopkinson. SpinningSpark 12:54, 17 March 2018 (UTC)

I might be changing my mind about Joule, the cited source is actually a collection of earlier papers. The paper in question is cited to Annals of Electricity vol. 5 which would put it in 1840/41 although I can't find the original paper in the volume because the pagination seems to be screwed up. We still have the problem of no secondary sources and duplication. SpinningSpark 15:02, 17 March 2018 (UTC)

Problem with the schematic at the top of the page

The schematic at the top of the page shows field lines that are not perpendicular to the material at the interface between air and the material.

In my understanding of ferromagnetism, field lines should leave the material with a right angle. Dosettes-beryl (talk) 16:43, 13 January 2024 (UTC)

You can download and edit the image, upload the edited version, and then use it in the article. Rotideypoc41352 (talk · contribs) 16:58, 13 January 2024 (UTC)