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Interesting idea but I don't think so. Basically this hysteresis uses a bit of energy each time the direction of the current changes in the coil. Power = energy x freq. so the power demanded by this hysteresis increases with frequency of current direction change. Maybe this power could be somehow represented as a frequency dependent resistance, but it is not to my knowledge. The resistances that are part of the Q factor are all small-signal resistances, and this would be a large-signal resistance, which is definitely not part of DCR. [[User:Snafflekid|Snafflekid]] 07:23, 14 October 2005 (UTC)
Interesting idea but I don't think so. Basically this hysteresis uses a bit of energy each time the direction of the current changes in the coil. Power = energy x freq. so the power demanded by this hysteresis increases with frequency of current direction change. Maybe this power could be somehow represented as a frequency dependent resistance, but it is not to my knowledge. The resistances that are part of the Q factor are all small-signal resistances, and this would be a large-signal resistance, which is definitely not part of DCR. [[User:Snafflekid|Snafflekid]] 07:23, 14 October 2005 (UTC)

* after putting my thinking cap on I remembered that the hysteresis is represented by magnetizing inductance, which is in parallel with the coil. The magnetizing inductance requires magnetizing current. So no, hysteresis is not reflected in ESR. [[User:Snafflekid|Snafflekid]] 16:53, 14 October 2005 (UTC)



:''All practical inductors exhibit losses due to the resistance of the wire or absorption by materials within the magnetic field surrounding it. It is possible to model these losses as a resistance, R, in series with a perfect or loss free inductance L.'' - From[http://www.ee.surrey.ac.uk/Workshop/advice/coils/power_loss.html] [[User:Meggar|Meggar]] 01:57, 21 September 2005 (UTC)
:''All practical inductors exhibit losses due to the resistance of the wire or absorption by materials within the magnetic field surrounding it. It is possible to model these losses as a resistance, R, in series with a perfect or loss free inductance L.'' - From[http://www.ee.surrey.ac.uk/Workshop/advice/coils/power_loss.html] [[User:Meggar|Meggar]] 01:57, 21 September 2005 (UTC)

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ESR in capacitors

How does leakage thro' the dielectric of a capacitor affect its ESR, I wonder??--Light current 04:26, 12 September 2005 (UTC)[reply]

Oh yes. Nearly forgot. What are the other factors affecting the ESR?--Light current 04:29, 12 September 2005 (UTC)[reply]

Isolating transformer- is this statement really true??

An isolating transformer uses its ESR to limit current. I have never heard this one before. Does anyone have any references please before I alter this statement??--Light current 04:33, 20 September 2005 (UTC)[reply]

There won't be a reference for that. A standard isolating transformer will have a low ESR to keep output voltage steady with load changes. On short circuit it will burn out unless protected by a fuse. Meggar 05:05, 20 September 2005 (UTC)[reply]

Yeah. thats what I thought. but I thought I'd check-- just in case!--Light current 11:48, 20 September 2005 (UTC)[reply]

I suppose that the author may have been thinking about why an isolation transformer is used - to isolate the Earth reference from the chassis so that a fault current to Earth will be very small. So, in this broad sense, you could say that the isolation transformer limits the fault current. This, however has nothing to do with ESR. Alfred Centauri 13:14, 20 September 2005 (UTC)[reply]

Is hysteresis reflected in increases esr for inductors?

I dont know about this one. Does hysteresis of a core affect coils esr?--Light current 21:12, 20 September 2005 (UTC)[reply]

Interesting idea but I don't think so. Basically this hysteresis uses a bit of energy each time the direction of the current changes in the coil. Power = energy x freq. so the power demanded by this hysteresis increases with frequency of current direction change. Maybe this power could be somehow represented as a frequency dependent resistance, but it is not to my knowledge. The resistances that are part of the Q factor are all small-signal resistances, and this would be a large-signal resistance, which is definitely not part of DCR. Snafflekid 07:23, 14 October 2005 (UTC)[reply]

  • after putting my thinking cap on I remembered that the hysteresis is represented by magnetizing inductance, which is in parallel with the coil. The magnetizing inductance requires magnetizing current. So no, hysteresis is not reflected in ESR. Snafflekid 16:53, 14 October 2005 (UTC)[reply]


All practical inductors exhibit losses due to the resistance of the wire or absorption by materials within the magnetic field surrounding it. It is possible to model these losses as a resistance, R, in series with a perfect or loss free inductance L. - From[1] Meggar 01:57, 21 September 2005 (UTC)[reply]

THis ref [2] only quotes resistive losses in inductors. It doesnt mention the term ESR--Light current 21:23, 25 September 2005 (UTC)[reply]

As far as I know, ESR is not quoted for inductors. What is quoted is the Q. I believe ESR is limited to capacitors- unless someone else knows different!--Light current 06:39, 25 September 2005 (UTC)[reply]

Clean up

Page needs some serious work I feel. Coiuld do with a diagram or two and a bit more detail. Any offers?--Light current 15:07, 23 September 2005 (UTC)[reply]

Adding diagrams and more detail is not "cleanup". Gene Nygaard 15:58, 23 September 2005 (UTC)[reply]

Clean up is covered under my mention of 'serious work' & 'more details'--Light current 16:36, 23 September 2005 (UTC)][reply]

No, it isn't (as I already pointed out in the case of "more details"). Tell me what is currently here and in need of cleanup. If nothing, or nothing that cannot be easily fixed, go find the proper tag to add here and remove the cleanup tag, or I will. Gene Nygaard 17:01, 23 September 2005 (UTC)[reply]

If you actually read the cleanup tag: {{cleanup}} you will see that it refers to the article as being of insufficient quality. Its the name of the tag thats wrong, not my usage of it.--Light current 14:23, 25 September 2005 (UTC)[reply]

I don't see any real problem with the tag; cleanup is just one factor affecting quality. Gene Nygaard 19:50, 25 September 2005 (UTC)[reply]
Usually this sort of request is what people use {{expansion}} for. "Cleanup" is generally used for remedial work - cleanup, as in what you do to a mess. -- Beland 03:20, 29 September 2005 (UTC)[reply]

Merge or redirect?

There isnt really enough meat in this subject at the moment to sustain a separate article I feel. Any thoughts?--Light current 06:36, 25 September 2005 (UTC)[reply]

Does Meggar have any more details on the application of ESR to circuits in general?. I'm not familiar with this particular use of the term. Could Meggar also say how this measurement is done? As I said I think the term Q covers it for coils-- unless youre talking about dc resistance which is not the same as ESR --Light current 21:21, 25 September 2005 (UTC)[reply]

Yes, the ESR is not the DC resistance. I did put up the entry about hysteresis and eddy current losses adding to the DC resistance. Do you see that small equivilent circuit in dashed lines under the quote in the above link? The one showing an equivilent resistor representing the sum of the various losses in series with an ideal inductor? Both coils and capacitors have ESR and Q ratings, the two are inseperable. A drawing could be added to expand this, but it is futile since there is also a merge tag. If you are intent on merging it there is no point in making it too big to fit back into the capacitor article. How about picking one of these incompatable tags and removing the other? Meggar 04:42, 27 September 2005 (UTC)[reply]

I ve looked at the link quite carefully, but I cant see the diagram to which you refer. Could you say exactly where it is please?--Light current 04:59, 27 September 2005 (UTC)[reply]

Here is a link to the .gif [3]. Meggar 06:17, 10 October 2005 (UTC)[reply]

Yes I see it. ESR is not mentioned but Q is. Thats what Ive been saying about coils!--Light current 06:28, 10 October 2005 (UTC)[reply]

I recommend that the page be turned into a disambiguation page, because ESR refers to both capacitors and inductors. I know that inductors are not spec'ed in terms of ESR, but it is still correct to speak of the ESR in an inductor, in circuit analysis. A redirect just to capacitor is too simplistic IMO. I can do this, in the free time I have between my 3 chip projects and 2 grad classes, ugh. Snafflekid 22:17, 12 October 2005 (UTC)[reply]

No I disagree!. ESR is NEVER referrred to WRT inductors. Give me a quote!.--Light current 02:19, 13 October 2005 (UTC)[reply]

There are some here [4]. ESR isn't a term, only an abbreviation. The full phrase is used for many things. ESR is also a common spec for quartz crystals. Meggar 03:00, 13 October 2005 (UTC)[reply]

It seems that ESR is used in the SMPS world to describe the non idealites of inductors. OK. In other circuits however the term Q is exclusively used. If we mention ESRs narrow applicability to electronic power supplies, I suppose I could drop my objection to its use for certain types (not all) of inductor application.--Light current 00:42, 14 October 2005 (UTC)[reply]

You are correct (BTW that's what I do, switch-mode power supply ICs). Some background--"Q" of an inductor is important in resonant circuits, because the "R" that is part of the "Q" could be two or three R's, has frequency dependence and does not lend itself to the concept of lumped elements and is not necessarily a series resistance either. "Q" factor is also a function of frequency. Inductors have DC resistance spec'ed because when they saturate, they turn into resistors, or worse fuses, and also to power rate them. DCR is an important spec for SMPS because significant current is in the inductor, Q factor isn't. This DCR value is the value of the ESR element when shown in circuit diagrams. I think this naming convention is historical. Calling it DCR must be intuitive because it's measured with an ohmmeter. Have I beaten this dead horse enough? Snafflekid 06:48, 14 October 2005 (UTC)[reply]