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#1
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B-H curve for transformer steel
Anyone got a complete DC B-H initial curve and loop for GOSS, or
link to same? I need scale and enough detail to extract data for regression. M4 or M2 would be best. Suggestions as to the best function to fit to the initial curve would be appreciated too. Ideally it should be continuous through the origin, and be symmetrical in first and third quadrants, asymptotic to B/H = µ0, and get close to the initial curve from the origin. Wish I had paid more attention to statistical distributions at school coz I suspect that's what is needed. BTW, with reference to earlier contributions on core losses, I find frequent reference to skin effect in windings, and its equivalent in the magnetic circuit of the core, but I haven't found any data. Also BTW, what are we going to do for transformers when everyone else is using switched mode for everything? Will GOSS sheet become hard to find? I gather for large transformers in power grids, amorphous is being dumped on the "third world" because it is not much good, so perhaps GOSS has a secure future there. cheers, Ian |
#2
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On Thu, 31 Mar 2005 10:56:07 GMT, "Ian Iveson"
wrote: Anyone got a complete DC B-H initial curve and loop for GOSS, or link to same? I need scale and enough detail to extract data for regression. M4 or M2 would be best. Suggestions as to the best function to fit to the initial curve would be appreciated too. Ideally it should be continuous through the origin, and be symmetrical in first and third quadrants, asymptotic to B/H = µ0, and get close to the initial curve from the origin. Wish I had paid more attention to statistical distributions at school coz I suspect that's what is needed. BTW, with reference to earlier contributions on core losses, I find frequent reference to skin effect in windings, and its equivalent in the magnetic circuit of the core, but I haven't found any data. Also BTW, what are we going to do for transformers when everyone else is using switched mode for everything? Will GOSS sheet become hard to find? I gather for large transformers in power grids, amorphous is being dumped on the "third world" because it is not much good, so perhaps GOSS has a secure future there. cheers, Ian You can go to www.tempel.com and get the data on all grades of steel including grain oriented steel. Jerry |
#3
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Ian Iveson wrote: Anyone got a complete DC B-H initial curve and loop for GOSS, or link to same? I need scale and enough detail to extract data for regression. M4 or M2 would be best. Suggestions as to the best function to fit to the initial curve would be appreciated too. Ideally it should be continuous through the origin, and be symmetrical in first and third quadrants, asymptotic to B/H = µ0, and get close to the initial curve from the origin. Wish I had paid more attention to statistical distributions at school coz I suspect that's what is needed. BTW, with reference to earlier contributions on core losses, I find frequent reference to skin effect in windings, and its equivalent in the magnetic circuit of the core, but I haven't found any data. Also BTW, what are we going to do for transformers when everyone else is using switched mode for everything? Will GOSS sheet become hard to find? I gather for large transformers in power grids, amorphous is being dumped on the "third world" because it is not much good, so perhaps GOSS has a secure future there. cheers, Ian SMPS are not entirely dominating designs for PS or causing dramatic falls in GOSS production. It has become routine for steel companies to make decent GOSS, and its real price is cheaper than ever before. It is in demand because it is cost effective against non oriented iron with higher losses where weight is an issue, like in an amp or microwave oven for export, and it does not have to be interleaved when a tranny is wound; butting and machine welding is a cheaper more effective mass manufacturing method. There are millions of tones of inductors used in lighting, flurescents and sodium street lights use inductors. Thre there are all the electric motors which need GOSS to run cooler, and be lighter. So GOSS will be around for awhile since there is little that can replace it. Curves and properties of GOSS is at a few websites if you search. Its not easy to understand all data you find. Better to compare measurements with differently cored OPTs to find out what happens at extremes of F. Patrick Turner. e |
#4
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"Gerald Stombaugh" wrote
You can go to www.tempel.com and get the data on all grades of steel including grain oriented steel. Unfortunately not. I've searched for ages. Perhaps I will email one of the suppliers. Tempel only goes to M6, BTW. cheers, Ian. |
#5
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"Patrick Turner" wrote
Curves and properties of GOSS is at a few websites if you search. An example would be useful. I wouldn't have asked if I hadn't looked already. Its not easy to understand all data you find. The principles are nice and simple, but not so easy to model as an electrical circuit. The main problem is finding detailed data measured under stated conditions. Better to compare measurements with differently cored OPTs to find out what happens at extremes of F. If I could measure flux inside the core...but I can't. I hoped it might be easier to find a BH curve. So GOSS will be around for awhile since there is little that can replace it. Phew. cheers, Ian |
#6
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Ian Iveson wrote: "Patrick Turner" wrote Curves and properties of GOSS is at a few websites if you search. An example would be useful. I wouldn't have asked if I hadn't looked already. The basic facts about transformers might be found, but sure, you are right, not many give the nitty gritty details. Maybe you'd find more in a university library. Its not easy to understand all data you find. The principles are nice and simple, but not so easy to model as an electrical circuit. The main problem is finding detailed data measured under stated conditions. Better to compare measurements with differently cored OPTs to find out what happens at extremes of F. If I could measure flux inside the core...but I can't. I hoped it might be easier to find a BH curve. But at the end of the day, we need to know what the final results are, so if the OPT has a low Fsat, low distortion, wide bw, etc, then the steel must be OK. Users want to know if the BH curves are good, or bad. They will choose good over bad if the price is right. Audio nutters like us who worry and fuss over OPT construction are of no concern to large companies mainly making GOSS for major mainstream electical engineering. Most of them know how to make good iron for a mains tranny, but as F rises the knowlege rolls off. If you want to consider the BH curves from the purist's position, surely you ned to at least understand how they are measured, signal used, circuit, CRO method, and so on. The methods haven't changed much perhaps, and a search in a uni library would be where I'd go if BH measurment and knowledge isn't to be found on the web. I am grateful to have learnt so much from days spent in university archives in the cool basements of university buildings. I haven't seen too much pure theoretical stuff on the web. Tempel just have the details of the gear they sell and a clearly expressed message :- "we make the best". That's debatable of course. So GOSS will be around for awhile since there is little that can replace it. Phew. One could use cobalt cores. Bleedin expensive. If GOSS were to vanish, amorphous would become common, and cheaper, but whether it translates to better music is a moot point. The bretheren at Lundahl wax lyrical about amorphous cores, but offer not one syllable or graph explaining why amorphous is better from the technical point of view. Patrick Turner. cheers, Ian |
#7
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On Thu, 31 Mar 2005 10:56:07 GMT, "Ian Iveson" wrote:
Anyone got a complete DC B-H initial curve and loop for GOSS, or link to same? I need scale and enough detail to extract data for regression. M4 or M2 would be best. Suggestions as to the best function to fit to the initial curve would be appreciated too. Ideally it should be continuous through the origin, and be symmetrical in first and third quadrants, asymptotic to B/H = µ0, and get close to the initial curve from the origin. Wish I had paid more attention to statistical distributions at school coz I suspect that's what is needed. BTW, with reference to earlier contributions on core losses, I find frequent reference to skin effect in windings, and its equivalent in the magnetic circuit of the core, but I haven't found any data. Also BTW, what are we going to do for transformers when everyone else is using switched mode for everything? Will GOSS sheet become hard to find? I gather for large transformers in power grids, amorphous is being dumped on the "third world" because it is not much good, so perhaps GOSS has a secure future there. cheers, Ian There's some good info on grain oriented steel at: http://www.transformercore.com/technical.htm On another page they give some technical data, and 2/3 of the way down the page they say curves are available on request: http://www.transformercore.com/CRGO.htm I've noticed that the grades of steel better than M6 aren't readily available in the states, but there seem to be a number of overseas suppliers. |
#8
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On Thu, 31 Mar 2005 10:56:07 GMT, "Ian Iveson" wrote:
Anyone got a complete DC B-H initial curve and loop for GOSS, or link to same? I need scale and enough detail to extract data for regression. M4 or M2 would be best. Suggestions as to the best function to fit to the initial curve would be appreciated too. Ideally it should be continuous through the origin, and be symmetrical in first and third quadrants, asymptotic to B/H = µ0, and get close to the initial curve from the origin. Wish I had paid more attention to statistical distributions at school coz I suspect that's what is needed. BTW, with reference to earlier contributions on core losses, I find frequent reference to skin effect in windings, and its equivalent in the magnetic circuit of the core, but I haven't found any data. Also BTW, what are we going to do for transformers when everyone else is using switched mode for everything? Will GOSS sheet become hard to find? I gather for large transformers in power grids, amorphous is being dumped on the "third world" because it is not much good, so perhaps GOSS has a secure future there. cheers, Ian ARMCO Steel was one of the early developers and suppliers of GOSS and they have been bought by AK Steel. They supply grades as good as M2. See: http://www.aksteel.com/markets_products/electrical.asp They have some data you can download at: http://www.aksteel.com/markets_produ...l_oriented.asp but there are no curves. You may have to ask to get them. |
#9
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"The Phantom" wrote
ARMCO Steel was one of the early developers and suppliers of GOSS and they have been bought by AK Steel. They supply grades as good as M2. See: http://www.aksteel.com/markets_products/electrical.asp They have some data you can download at: http://www.aksteel.com/markets_produ...l_oriented.asp but there are no curves. You may have to ask to get them. Thanks for both, er, Phantom! Loved the diagram of squashed coils, and the general enthusiasm of the Indian site. I have e-mailed them asking for curves. Interesting stuff, iron. A serendipitous phenomenon, like water. Hence the iron age, I suppose. Still struggling with the maths so no great rush. Seems I need a hyperbolic cotangent but spice isn't keen. cheers, Ian |
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