Talk:Electronics/Transformer Design

All,

I want to address some questions from where this was originally posted under wikipeida and moved here.

When I started this article, it was mainly for the basics of transformer design. It has been modified somewhat by several, especially mentioning the use of CAD software. In reality, the large transformer manufacturers use this method as they weigh cost and service life to get the most for their buck. Smaller companies who manufacture transformers under 10 kVA rely on the old design methods. In actuality, the CAD programs still use Maxwell's equations in their core, and so is the basis for every design. No matter the type of core in a transformer, these equations are still used today, and are in the most recent books published on the matter. This can be seen by the works of Colonel William T. McLyman who designs transformers for NASA, and he has written several books, along with some software on the subject. As regards for the references in the article, and their dates, they have all be carried over into the newest reprints of the books. Some new technology has been added, mainly in the alloy's used in the cores, and insulation used in the windings.

As far as other core types, there is already a page in wikipedia for them, if I recall, and was the main reason I never included them. At this though, toroids, Kuhlman Electric type folded cores, and G.E. type spiral cores are calculated the same as a standard EI core or C-Core.

RF transformers that use Ferrite are essentially matching transformers, and are the same as audio transformers. The core material is different between the two because of the frequency they are ran at. These were not added either as if I recall, there was a wikipedia article about them somewhere else. These would be under impedance matching transformers.

Someone mentioned something about switching transformers. They can run on square waves or modified square waves, etc. The formula is adjusted in square wave usage, and the multiplier is changed from 4.44 to 4.0, and is addressed in the article. This, and the core using different alloy's with thinner strips, is the only difference to standard EI core transformers running at 50-60 Hz., and is due to the higher frequency they are ran at. Therefore, these are designed the same as a standard transformer.

I stopped writing the article in 2006, and was hoping for others to add to it. Maybe someone could add something about how toroidal transformers are wound, as the machinery is totally different than a simple lathe that is used in EI and C-Core core transformers.

Last, please reference wikipedia with a search for transformer types, and transformer cores.

craxd 03-07-2009

Modeling Software
Today, I edited the first paragraph about using modeling software. The way the paragraph read, it dismissed the importance of the calculations and equations; the same ones that are written into the softwares code. The paragraph made it seem that using software was the only way to design large transformers or mass produced ones which is simply not the case.

Computer modeling may be fine for larger companies, but smaller manufacturers do not use it, mainly due to its cost, and they use either simpler design software that is indeed on the market, or do it by hand on paper.

craxd 03-07-2009

Edit & Cleanup
I cleaned up some text, and corrected some minor things, along with adding several pics to the page.Craxd1 (discuss • contribs) 19:08, 3 February 2013 (UTC)

I added some photos today, along with cleaning up the opening text.Craxd1 (discuss • contribs) 00:15, 19 February 2013 (UTC)

What is the window area
This page uses the term window area many times but doesn't seem to define what it means. w:user:plugwash

The window area is simply the window width times its height. There are two windows on a transformer using EI laminations, on either side of the core. I will add this to the content.

w:user:craxd

Window Area
I added the description of the window area measurement to both the section about the coil calculation, and the formula section under the WA product.

Craxd 9/18/10

DC switching transformers
I added a description of DC switching transformers at the bottom of the page. --Craxd1 (talk) 22:01, 18 September 2010 (UTC)

RF Transformers and Photos
I added a section on RF and audio impedance transformers, along with some cleaning up of the text. I also added three pictures to the text. --Craxd1 (talk) 06:35, 20 September 2010 (UTC)

Volt-Amperes
I corrected some things I found about the power factor, and added two links. --Craxd1 (discuss • contribs) 04:19, 10 February 2011 (UTC)

Adrignola, checking the book.
Adrignola,

Thanks for helping with this.

I noticed, too, that someone had added a long list of things on how 'they' constructed their transformers, and made it sound like a sales promotion, although they didn't list who did it this way. Here, I finally deleted this, as it was practically unreadable. I didn't know whether you saw this or not, but it was taken out by me.

Really, I haven't found the time to work on this in a while, and just happened to drop by to see that it had been cleaned up a bit. --Craxd1 (discuss • contribs) 08:22, 6 January 2012 (UTC)

source for BH curves
hi, i'm looking for more data like this http://upload.wikimedia.org/wikipedia/commons/f/f9/B-H_Curve.jpg, particularly for NOES (CRNO) steels, their B-H curves and core loss curves. Can't seem to find any on the internet that fall into that category (like M22, M15).

I can not find any similar either. I think that one was a screenshot from a computer application for designing transformers, but which one, I'm not sure.--Craxd (discuss • contribs) 20:42, 24 May 2014 (UTC)

the formula, the equation?!
Section "Power transformer design" constantly refers to "the formula" and "the equation" without linking which equation. This is a mess as it is hard to know which design equations the article is talking about without having some initial knowledge about the governing equations for transformers. In most scientific writing it is common place to number the equations, which I presume are derived in the section "Equations", and reference those numbers when talking about specific equations.

You have to list it as 'the equations', since either can be picked to arrive at what is needed, but the one to size the core by its power rating is always the first one, and the others should equal the same sums. However, to use the one for the core size by power, the power has to be calculated using the DC power equations if the load(s) is/are reactive.--Craxd (discuss • contribs) 20:48, 24 May 2014 (UTC)

Power equation
This seems to be wrong. The factor of 0.707 which I assume comes from 1/rt2, is not correct. Having done the algebra, it should be pi x rt2. I have verified this also by actually measuring a couple of commercial transformers as a check and using a current density of 1.8 amps/mm2. The current in the wires can be expressed as J*W/N. Rearrange the equation for E in terms of N and substitute, multiply by E to give E*I. I am reluctant to change this however since it all depends on how you measure the window area W because the primary takes only 50% of the area. That would bring in a factor of 2, but regardless of this there still seems to be a pi missing. Maybe someone else might want to chime in.

Further more, the equation is missing a factor of 1E-8. The equation seems to be using S.I. units rather than c.g.s. which would account for the error. It is important to be consistent with the units in this section. JohnPearcey (discuss • contribs) 19:30, 27 September 2023 (UTC)