Talk:Magnetic core

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Core saturation is a critical consideration. There is a limit to the magnetic flux a core will carry. You really can not use magnetic cores safely without knowing about saturation. Air gaps are often used to avoid saturation. B/H curves could be shown and discussed.

There are already articles on Saturation (magnetic) and Saturable reactor and Hysteresis that can help. The hysteresis article covers all uses of the term, but does show a B/H curve. The Magnetic amplifier article references these, plus magnetic core and transformer.

The Transformer article also talks about cores, but omits pot cores. That article could benefit from this one.

AJim 03:48, 25 July 2007 (UTC)

Shaping magnetic fields

I notice that commercial magnetic knife holders all seem to have a few magnets surrounded by steel (e.g.). This configuration seems to be what is used in a magnetic base as well. Is this steel acting as a magnetic core? If I wanted to create a magnetic field that extended out particularly far from a permanent magnet, what shape magnet would I use and where would I put the steel? —Ben FrantzDale (talk) 12:07, 20 June 2008 (UTC)

"Soft" iron?

What is "soft" iron? Is it elemental iron (which is mechanically fairly soft) as opposed to steel, which has a little carbon in it, or cast iron which has a lot of carbon in it?

In this case "soft" is not referring to the mechanical property of hardness, rather to the magnetic property. A material that is magnetically "soft" is one that does not remain highly magnetised when an externally applied magnetic field is not present (i.e. has a low Coercivity and low Remanence)
202.12.105.132 (talk) 03:30, 23 July 2009 (UTC)

Merging "Ferrite bead" article over here

There was an article called "ferrite bead" which was apparently written by someone who doesn't know the proper terminology for this technology. I have turned the article into a redirect to here and I am putting whatever was useful from that article and merging it into this one... images, See Also, External links, and Translation links.

I created a section that tries to keep some of the "bead" article alive, distinguishing between a "torus" and a "ring/bead", though honestly I don't know if this is a valid distinction. The only major distinguishing factor is the application: toroids are usually wound multiple times around the perimeter, while the cylinders are axial only and the conductors usually only pass through the center of cylinder.

I'm going to have to defer to someone with more expertise in the field than me, to decide whether to keep the ring/bead section separate or merge it as an application of the toroid.

DMahalko (talk) 06:07, 23 March 2009 (UTC)

Missing theory of core losses, redirect or add in?

A couple weeks ago I added in a pictorial discussion of "parasitic induction" into the article on Faraday's law of induction. After finding this article today I see the information is useful as a discussion of why laminations or ceramics are used though the topic material is not totally specific to this one "applications of induction" article.

Electromagnetic induction#Parasitic induction and waste heating

I suppose I could merge in some of the images and have a jump-over redirect to that as the main article.

DMahalko (talk) 06:36, 23 March 2009 (UTC)

Section: Ferrite

In my opinion this section should redirect to Ferrite (iron) instead of Ferrite (magnet). —Preceding unsigned comment added by 20.133.32.18 (talk) 06:28, 10 September 2009 (UTC)

Laminations

I added a picture of an EI lamination under the section about Silicon steel lams. It is the same photo I uploaded to use with the Wikibook article I authored on Transformer Design.--Craxd (talk) 11:34, 20 September 2010 (UTC)

There is at least one core shape omitted: it consists of two pieces, the first is H-shaped, the second is rectangular ring; it was designed for miniature inductors of high inductance, where it has advantages over other core shapes: easy coil winding (using the H) and little permeance loss caused by gap (due to large area of contact between these two parts); note some gap is unavoidable (except ring ang bead cores), because of dust on contacting surfaces and imperfections of their polishing.

JerzyTarasiuk (talk) 06:43, 15 July 2015 (UTC)

Rod?

I don't agree to the term "Rod" refering to the coil's core. The definitions of "rod" in the wikipedia agrees. A rod is a rod is a rod. — Preceding unsigned comment added by 2.80.207.209 (talk) 13:51, 17 April 2012 (UTC)

Revert of removal of air core

Chetvorno removed air cores but I reverted the edit. Although an air core may or may not be considered a magnetic core, the section is equivalent to a section explaining why cores with a permeability above 1 are not always used, and that is clearly on-topic.GliderMaven (talk) 17:06, 29 November 2017 (UTC)

Chetvorno's most recent edits were last month. In the last couple of days you have 3RR'ed [1][2][3] in the text that "magnetic cores are only usually magnetic". This is nonsense. Magnetic cores are of magnetic materials, that's their definition.

Air cored coils are not magnetic cores. They should be briefly included here (I would agree with you on that point) as they are commonplace and a contrast to using a magnetic core instead. But they are not magnetic cores themselves. Andy Dingley (talk) 09:50, 16 December 2017 (UTC)

My reason for removing the section Air, which I still support, is that (1) Air core coils are already discussed in the introduction to the Core materials section. All the information can be put here, there is no need for a redundant discussion. (2)"Air core" coils do not necessarily have air as a core material; the term refers to any coil that does not have a ferromagnetic core. Even though this is stated in the section, listing "Air" under Core materials gives readers the false impression that that is what the core is made of. I would like to hear what other editors think about this.--Chetvorno^TALK 16:19, 16 December 2017 (UTC)

@GliderMaven: I support Andy Dingley and Wtshymanski's reversion of your edits to the introduction. This kind of freakishly stuffy, pedantic editing and tortured logic is exactly why Wikipedia technical articles have a reputation for being incomprehensible. --Chetvorno^TALK 16:19, 16 December 2017 (UTC)

There's many subtleties here. Things like: what mu is the borderline between a 'magnetic core' and a 'non' magnetic core? It says 'high', what the heck does that mean???? Note that free space supports magnetism otherwise air cores wouldn't work, it doesn't have zero or negative permeability. If air cores don't go in this article where do they go??? Or, if they are covered in the article, how does the reader know that the article covers air cores, since it's not mentioned in the lead at all right now because you guys repeatedly have deleted all mention of it?GliderMaven (talk) 01:17, 22 December 2017 (UTC)

EI Lamination: does the current inducted by the coil pass from the E to the I metal sheet?

This information is missing. I know that each layer of sheet is insulated, but what about the E ad I sheet? Does the current that is inducted under the primary coil goes under the secondary coil (or are the E and I plates insulated from each other?)? I would guess that the core doesn't need to be a conductive loop (to induce a magnetic field needed to move electrons of the secondary coil). Am I wrong? Nestashi (talk) 13:34, 27 October 2019 (UTC)

Right, the core doesn't need to be electrically conductive, it just needs to be a closed loop of ferromagnetic material, to provide a closed loop path for the magnetic field lines. The separate "E" and "I" pieces are usually butted together and held in place with some kind of plastic potting. The eddy currents flow in closed loops in planes perpendicular to the magnetic field lines, across the width of the core pieces, so it doesn't matter if the ends of the "E" and "I" laminations are in electrical contact, as the current doesn't flow in that direction. In most transformers the E and I laminations are interleaved by reversing the E and I pieces in alternate layers, to give the core more strength. --Chetvorno^TALK 18:03, 27 October 2019 (UTC)