Talk:Transformer/Archive 1

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FAC

I think this is good candidtate for Featured article consideration, once we get it stable. Thoughts?--Light current 18:52, 12 January 2006 (UTC)

A basic explanation would be nice

This article is too technical to the lay man, making no effort to explain to those unfamiliar with electronics what a transformer is and does, or even how it works. I suspect that many who've read this have become lost in a sea of technical terms in an attempt to garner some intelligable information, and have probably given up trying. Learning about the meaning of each and every single term and word used on this article is a pointless waste of time and energy if all that's needed is a simple explanation of the JOB and PURPOSE of a transformer, and possibly a few words on how they work - this explanation should be understandable with a bare minimum knowledge of basic electronics. This can be added at the beginning as a "basic explanation" or added alongside each section to clarify.

Before anyone launches into a critical rebuttal telling me that I'm wrong to ask for such a thing, please consider that wikipedia is for everyone, not just experts or students - this article requires a higher level of knowledge to understand than it should, making it inaccessible and unhelpful to a large number of people, and practically assumes that people who fall below that level of knowledge wouldn't have a reason to search for "transformer" anyway. There are numerous people who would probably like to get into electronics whose lives would be made easier by simplified explanations, as well as just casual readers curious about what a transformer is and does (it is afterall a common piece of equipment in domestic electronics), who would benefit from a simpler explanation. Regardless of the reasons people might have for looking up this article, the required level of knowledge for it is too high, and I am therefore marking it as being too technical. Please discuss this by responding to my post here on the talk page.

--Badharlick 04:54, 14 November 2005 (UTC)

hi,First of all without technical words it is really very difficult to describe any electrical or electronic device,still one can simplify it. Secondly one has to stretch his brain to understand such devices though they are simplified.

In a lehmans language i can say transformer is a static device which changes the volatge levels(either increase it or decrease it) without changing frequency. Now why it is necessary to change the voltage levels? Different devices that we use in our offices or homes or industries they are designed for specific voltages and frequency.It may be different for different devices.To make these devices work we have to supply them with appropriate voltages.For that we use transformers.

From generation to end devices, voltage is stepped up and down at various points. In fact, genaration volatge is quite less than transmission. It is generally in the range of 11kv to 16kv. It is so because generators are always rotating devices, for high volatages,insulation may be the problem. Thats why generating volatge is kept low. After that volatge is stepped up to a very high level(in the range of 400kv). These transformers are generally called as "power transformers".- Shilpa Choudhari

Maybe we need a simple digaram of a core with a couple of windings round it and showing the mag flux to show how it works?--Light current 16:31, 30 November 2005 (UTC)

Good idea. I learned a lot by taking apart transformers when I was in grade school. It would be good if the diagram shows two coils, one with twice as many as the other to show step up/down ratio. On a related note, how about comparing a transformer to a transmission with two gears, one small, the other large? The turns ratio is like the gear ratio. You could also make analogies to RPM and torque as well. Madhu 22:20, 30 November 2005 (UTC)

I think there may be a copyright problem on this image--Light current 03:31, 2 December 2005 (UTC)

I really do not think so. After taking it from internet i have pasted it in Paint and modified a bit -

--Shilpa.Choudhari 04:47, 2 December 2005 (UTC)

I dont think you have modified it enough to make it look different enough so that people cant tell where its come from!!--Light current 03:34, 6 December 2005 (UTC)

The diagram is here. Let me first clarify that structure shown in diagram is just a representation of transformer. In actual,construction opf transformer is quite different. Alongwith Faraday's law you should also refer Lenz's law. Both the primary and secondary windings are wounded on the limbs of core. When primary is supplied with certain voltage, current flows through it. Flux is produced and flow through core. As both the windings are wounded on same core, by Faraday's law current is induced in secondary winding also. If you have a closed circuit at secondry you can measure current alse voltage can be measured across secondary. Volatge across secondary is proportional to turns in it. You can see it in diagram.--Shilpa Choudhari

proper theoretical treatment

We should have a proper theoretical treatment of how a transformer works, including treatment of:

• impedance transformation
• current ratio and voltage ratio
• non-linear effects and losses

Perhaps an elementary introduction using induced e.m.f. balance and conservation of energy is the right way to get into it? -- The Anome 08:10 12 Jul 2003 (UTC)

conversion to motion=loss?

I'm a little uncomfortable with

The energy converted to motion is one form of core loss.)

since some of that motion is not lost immediately, but stored as elastic compression. I expect resonating at the mains frequency might ameliorate the loss (or might destroy the unit!) and an inspection by a power-systems EE might be valuable here. --Jerzy(t) 01:19, 2004 Mar 5 (UTC)

There is a whole lot about energy storage that could be included. (I remember Professor Jerrold Zacharias pointing out that the trick in a necessarily simplified introduction was not teaching anything that would have to be unlearned later.) There is not only mechanical energy storage, but magnetic and even electrostatic energy storage to consider in a real transformer. You are right, some of the stored energy is recovered, some is dissipated. I am uncomfortable with leaving out any link to ideas related to power factor, the issue that the current and voltage waveforms may not be in phase. Maybe there is an article on reactive power to link. Also of practical importance is that transformers sometimes have non-sinusoidal waveforms applied. Harmonic distortion of nominally sinusoidal power waveforms can be a big problem. The imperfect relation between B and H is critical in practical transformers. A power transformer can overheat and fail if there is a significant DC component to the current, for instance. And you can not arbitrarily change the voltages applied - sucessful use depends on more than the turns ratio.

It is possible to have significant unintentional transformers. Some examples:

• AC wiring practice always uses two wires, and they are always run together.

If you run the two wires in two separate metalic conduits, for instance, you have created a simple transformer with a single turn secondary - the conduits, (and a single turn primary, the two wires) - the conduits can get quite hot.

• Twisted pair is often used in balanced circuits to minimize inductive coupling from ambient fields. However, if you have two circuits and you cross wire the twisted pairs, the circuit will look fine at DC, but transient signals in one circuit will transformer couple into the other circuit in a mysterious manner. The twisted pairs have become a transformer! The first time I encountered this wiring mistake it took a while to figure out.

This sounds a bit like a transmission line transformer to me. Light current 14:41, 3 September 2005 (UTC)

This is all good information, which I shall add to the article if I get time. Unless you do it first, of course. ;-) -- Heron 22:14, 5 Mar 2004 (UTC)

Pacinotti

I removed this line:

"Antonio Pacinotti (1860)"

from the list of inventors, because I can find no evidence that Pacinotti had anything to do with transformers. He did, however, invent a dynamo in 1860. Perhaps there was a mistranslation somewhere. -- Heron 20:06, 24 Jun 2004 (UTC)

---

The definition of transformer are related only to electromagnetic transformers. There are piezoelectric transformers, electronic transformers etc. Therefore definition must be: The electrical transformer is device, which transfers the power from input to output and changes the magnitude of input voltage (voltage transformers) or current (current transformers). Ilgaitis Prūsis.

Power transformers

I've added some content pertaining to power transformers, hysteresis, and fire-resistant cooling fluids. I'm not sure D'Arsonoval belongs here . I removed the pejorative description of PCBs as "toxic waste" since the people who invented PCB and thought it was perfect for the job didn't think of it as such. --Wtshymanski 17:21, 11 Dec 2004 (UTC)

Autotransformers?

Ignition coils and flyback transformers aren't autotransformers. An ignition coil only has three terminals, but there are two discrete windings that happen to share a ground connection. An ignition has far too high a ratio to benefit from an extra 12 volts on the primary. Similary with a flyback transformer.

Ignition coils (the old-fashioned kind that are used with spark distributor) are typically connected as an

autoformer with the center tap at ground. I am not aware of any rules that preclude autoformers from

changing wire size between taps, so I would say that most ignition coils are, in fact, autoformers.

The exceptions would be the coils that fire out both ends of the secondary, such as are used in DIS and

other direct-firing ignition systems.

I don't think a flyback transformer is "resonant" - as I understand them the flyback in a TV set captures the energy that's been stored in the deflection yoke, but is not a resonant circuit itself. I suppose an ignition coil is sort-of "resonant" since it does rely on energy storage as part of the spark generation process. I'd like to add some stuff about considerations in design of power transformers, in terms of trading off no-load and load losses...if this article hits 32K it will be time for a separate article on power transformers. --Wtshymanski 22:33, 16 Dec 2004 (UTC)

I can't say whether your average flyback is an autotransformer, but most flyback transformers used in ordinary television sets are definitely resonant. A common test for a suspect flyback used to be to apply a pulse and see if the transfomer "rang" (using an oscilloscope to monitor the voltage waveform of the ringing). If it did ring, the flyback was good, but defects like opens or shorted turns would kill the resonance. IIRC, they usually resonate at about 7 times the horizontal scan rate; this produces the best "flyback" of the trace.

I don't know how this works in multisync computer monitors; perhaps someone else can explain how they can be used at a wide range of sweep frequencies (or even a continuous range of sweep frequencies. At one point, I think multisync monitors used switched capacitors; perhaps nowadays high-voltage generation is separated from horizontal deflection and the horizontal deflection is just "brute-forced"?

Atlant 22:30, 28 Jan 2005 (UTC)

Years ago, several green screen monitors were discarded at the University. I pulled out the flybacks for use in high voltage bias supplies on our beam transport experiment. I conducted some simple tests to determine resonant frequency of a bare flyback and step up ratio. The secondary coil resonance was about 65 kHz, if I remember correctly. The step up was quite high, can't remember what it was though. The primary resonance was expectedly much higher. The sweep circuits were probably lifted from a standard B/W TV, so it's likely the sweep was standard [NTSC] of 15.75 kHz, so it wasn't exactly resonant. Like most solid state flyback circuits, it had a typical diode/cap tripler. My guess is the anode voltage was around 15 kV, so the flyback itself peaked at 5 kV. I think I was able to get as much as 30 kV out of it before the secondary broke down and arced out. Madhu 19:40, 21 August 2005 (UTC)

Step-across transformers

"step across" transformer appears to be a Wikipedia artifact only and is not actually used in the industry. I've been unable to locate a reference to that term either in my local library or on the Web, barring a bunch of quotes from Wikipedia itself. I've deleted this Wikifiction. --Wtshymanski 20:51, 28 Jan 2005 (UTC)

capacitive transformers

i heard there is a dual to the transformer, the capacitive transformer or electrostatic transformer, which I believe is just two coupling caps carrying AC to and fro so the circuits are floating relative to each other. does this deserve an article? are they used anywhere? - Omegatron 01:23, Mar 19, 2005 (UTC)

Capacitive voltage transformers exist and are used by utilities for high-voltage (greater than 66 kV) metering. They have a capacitive voltage divider but also have a dual-winding transformer to couple the divided voltage to the metering circuit. They tend to have lower allowable burdens than a wound transformer but can be made economically at higher voltage ratings. Another difference is that even though they decrease voltage, they do not increase current as found in wound electromagnetic transformers - an ampere drawn by the load is an ampere drawn from the primary circuit. And of course they can only reduce voltage, not increase. The article is talking about magnetically-coupled transformers and these "capacitive transformers" aren't really "transformers" in that sense. One could also mention optical "instrument transformers" but these don't use windings coupled by magnetic fields, either. --Wtshymanski 04:35, 19 Mar 2005 (UTC)

Hmmm... What I heard of was a purely capacitive device that operated in a way analogous or complementary to a transformer. This could be as simple as a coupling cap for all I know. Or it could not exist. It is the dual of an inductor transformer, as a capacitor is the dual of an inductor. By "optical instrument transformers" do you mean optocouplers? - Omegatron 00:33, Mar 24, 2005 (UTC)

I see what you mean, but I've never heard of a "dual" to a "magnetic" transformer. What the utilities call a "capacitive voltage tansformer" is really only a capacitive voltage divider. In a "magnetic" transformer you can have multiple turns around the same magnetic flux; in a "capacitive" device I don't see any way to do anything analogous. The lines of the electric field stop at the plates, so each plate can only "link" electric flux once. So you can't get the very useful property of changing voltages and currents so long as VI is roughly constant.

There used to be capacitive multplexers used to isolate analog signals from input to output - (may still exist, outside of my field) - these used two sets of relays, one to momentarily connect a capacitor to the input signal, and a second to connect the capacitor to the measuring circuit. This provided as much isolation as you could get in a pair of relay contacts, but wasn't a "transformer" as such.

No, an optical current transformer uses some hi-tech physics to turn a varying magnetic field into varying polarization of a beam of light - this is called the Faraday effect. For example see www.nxtphase.com/sub-products-optical_ current-nxct_current-transformer.htm , or of course ABB has them also at www.abb.com/global/seitp/seitp332.nsf/ 0/177a4854b28ce5d0c1256eaf002cc96f?OpenDocument - (what would we do without Google?). These devices are only called "transformers" because that's what utilities like to call them; it would be more accurate to call them "voltage/current transducers". An optocoupler usually is just an on/off signal, and doesn't provide an analog value. A quote I read says "Optocouplers are just signal fires writ small."--Wtshymanski 16:17, 24 Mar 2005 (UTC)

Huh. I guess I heard wrong. Don't forget about piezoelectric transformers. - Omegatron 02:13, May 28, 2005 (UTC)

a static electrical device

why "static"? - Omegatron 01:29, Mar 19, 2005 (UTC)

As opposed to devices with moving parts - a transformer changes voltage with (in principle) no moving parts, unlike, for example, motor-generator sets. --Wtshymanski 04:35, 19 Mar 2005 (UTC)

The current edit now says "no moving parts" - this isn't as accurate as "static". Prefixing "magneto-" or "electro-" shows that there is a root meaning, which meaning is the one I had intended. Large power tranformers, (at any rate), have numerous parts that have to keep moving for the transformer to keep operating.( When I was a kid I would have thought "transformer oil" was a joke, like "propwash" in pilot school - the oil moves!) And of course there are a couple of varieties of transformer where the major elements do move with respect to each other, but that motion isn't the basis for energy transfer between primary and secondary. --Wtshymanski 16:27, 24 Mar 2005 (UTC)

So "no moving parts" is not perfect, but I don't like "static", either. It doesn't convey the right idea with just that word; plus newcomers will associate with this kind of static. It should just have a sentence describing what you meant by static. - Omegatron 02:13, May 28, 2005 (UTC)

Strange edits

Is this work in progress or should we revert to an older edition, that's less scrambled up? At this point the article has duplicated sections and some text has been cut. What's up ? --Wtshymanski 20:16, 21 Mar 2005 (UTC)

i'll fix it; sorry. work in progress. - Omegatron 20:30, Mar 21, 2005 (UTC)

Sorry to "experiment" on a live article. In the future this will be less ugly. see Wikipedia_talk:Extended_image_syntax#Multiple_images_in_one_frame for progress. these three articles have such tables: Transistor#Types, transformer, BJT. - Omegatron 20:35, Mar 21, 2005 (UTC)

Poly Phase Transformer

Does any one know how these work or something like that? Is this just three seperate transformers? Thanks

No, true polyphase transformers have three sets of windings that share a single set of core laminations. The usual arrangement is to have a core that is shaped like the letter "E" but with the open end closed. One set of coils is placed around each of the "legs" of the E.

I think this works out nicely because the phase relationship means that some of the magnetism from one set of coils is opposed by magnetism from other sets of coils, allowing a proportionally-smaller core assembly than would be required by three completely-separate transformers. Here are some images from out on the web click..., click..., or click. The second and third clearly show the wiring of the HT side of the transformer.

Atlant 14:53, 15 Apr 2005 (UTC)

This sounds right to me. I think that its obviously far more economical to make a 3ph transformer on a 3 limb core than to have 3 separate transformers. I am pretty sure that the total max flux density in the core due to 3 ph is probably not much greater than it would be for single ph. due to the 120 deg ph diff between consec phases. Anyway, the total flux density in a transformer is zero (apart from magnetising flux )if the secondary is loaded properly. Light current 00:35, 3 September 2005 (UTC)

Name change

The name "transformer" is ambiguous, so I propose to change the name of this article to "electrical transformer" or "electric transformer". Which name is the more correct one? --surueña 16:24, 2005 May 24 (UTC)

Then again, the electrical use of the term may be the principal use, in which case things are just fine as they are. Certainly, when I look at the two dab alternatives we have today, I think they pale in significance to this usage.

Atlant 16:34, 24 May 2005 (UTC)

may i ask what other meanings you consider significan't enough to warrant such a move rather than just a link to a disambiguation page link at the top of the article? Plugwash 16:35, 24 May 2005 (UTC)

I'm not proposing the change because the term has other common meanings, but only because it is ambiguous and this can be easily corrected moving the article (and redirections are cheap, so it is not a performance penalty). In other articles it may be not obvious what are the destination of the link, so it is better to use the "whole" name. Another option is to have one redirection (or two) from "electrical transformer" or "electric transformer" to this article. I'm not a native English speaker so, are both names correct? Thanks --surueña 18:28, 2005 May 24 (UTC)

I am a native English speaker and practicing electrical engineer, so I can assure you with considerable confidence that the devices are never called "electric" transformers or "electrical" transformers. Transformer is a perfectly un-ambiguous word and has no other common meaning aside from the toy line. In my opinion any re-naming of the article would be a serious error and would be misleading to Wikipedia users. Articles about the toys should spell out what they mean if they have "overloaded" the meaning of transformer. Thanks again for the effort to build consensus. --Wtshymanski 21:34, 24 May 2005 (UTC)

BUT, the internet is used by more non-native English speakers.

Neither electric nor transformer are exclusively English words.

Rather: international words. Occuring in various forms.

And such can vary slightly (or completely) per region.

I am not saying I have a better idea for a title.

I would just like to point at a language problem we sooner or later need to solve on the internet.

[Hence, I could have posted this in any Wikipedia Talk-section].

When fussing about the right words for technical texts like these, we are lucky: it is scientific lingo, more standardized than abstract subjects.

--guest user 'Tristan'

2006-01-16

OK, last retry, I promise :-) What about a page named "Transformer (electrical)" or similar that redirects to this one? Thanks a lot --surueña 23:23, 2005 May 24 (UTC)

I think it's unecessary, and pointless, but considerably less of a problem than renaming this article. Will anyone actually type "Transformer {electrical)" when looking something up? Unlikely. Regards,--Wtshymanski 05:07, 25 May 2005 (UTC)

This article should stay under "transformer" and everything else should get parentheses. And I grew up playing with transformers (toy).  :-) - Omegatron 23:28, May 24, 2005 (UTC)

You're normal, I grew up playing with transformers (electrical) ;-) Madhu 18:57, 2 September 2005 (UTC)

Object. The largest ambiguity is due to those toys, which are disproportionately well-represented here on Wikipedia-at least the toy/movie articles are titled Transformers (toy line), etc. Neither of the proposed alternative names is more correct. I've spent a few hours looking up articles with "Transformers" and changing the links to the toys, movies, etc. where the electrical apparatus is not meant; anyone else who can spend 20 minutes on this would be a help. Thanks for asking first, though. --Wtshymanski 18:21, 24 May 2005 (UTC)

I've found a lot of Transformer (album) too, maybe there are still some of them. --surueña 23:23, 2005 May 24 (UTC)

I've got to admit, if I ever see a transformers (toy) that transforms into a transformer...I'm going to buy it. What would it's name be? "Pauwels" maybe, or "ABB"...--Wtshymanski 14:55, 11 August 2005 (UTC)

Wall warts and "no load" power consumption

So I always used to think that wall warts drew power while there was nothing connected to their outputs, since they are still a connection between the two wall terminals. Of course I forgot that it is an inductor which looks like a large resistance to the AC line. Mention this? - Omegatron 02:14, May 28, 2005 (UTC)

No, it looks like a large reactance!! Light current 23:49, 2 September 2005 (UTC)

Wall warts do draw both real and reactive power even under no load. Exactly how much depends on the design of the wall wart. Reactive power draw comes from the inductance of the transformer, Real power draw comes from the resistance of the coils and anything else that is connected inside such as regulater cuircuits, imperfect capacitors, imperfect diodes in a bridge design etc Plugwash 23:54, 2 September 2005 (UTC)

Don't forget core losses; I suspect that for a conventional transformer-based wall wart, that's probably the biggest source of no-load heating. (And, of course, nowadays, more and more of the wall warts are actually switching power supplies, running a bunch of high-frequency electronics whether loaded or not, so they have different no-load loss characteristics than the classical transformer-based warts.)

Atlant 19:42, 16 January 2006 (UTC)