Litz wire
in [Design]
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From: John Larkin on 20 Feb 2010 14:04 On Sat, 20 Feb 2010 11:01:23 -0800, life imitates life <pasticcio(a)thebarattheendoftheuniverse.org> wrote: >On Sat, 20 Feb 2010 07:46:39 -0800, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Sat, 20 Feb 2010 07:33:54 -0600, "amdx" <amdx(a)knology.net> wrote: >> >>> >>>"life imitates life" <pasticcio(a)thebarattheendoftheuniverse.org> wrote in >>>message news:sauun5t4ct7i1ule9dj0lsihmjv5u5ecvs(a)4ax.com... >>>> On Fri, 19 Feb 2010 17:57:41 -0800, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Fri, 19 Feb 2010 13:21:36 -0600, "Tim Williams" >>>>><tmoranwms(a)charter.net> wrote: >>>>> >>>>>>Who sells this stuff (without paying for miles at a time)? >>>>>> >>>>>>I'm especially interested in stupid thick stuff, like, as large as 8AWG >>>>>>equivalent. Nebraska Surplus for instance doesn't stock wire like this. >>>>>> >>>>>>Tim >>> >>> >>>> Trial and error with gauges and strand count do >>>> more to optimize the result than ANY specialized, presumed to be required >>>> braiding or weaving. The segregation is the key to increasing surface >>>> area within a given cumulative "gauge". >>> >>> No need to do trial and error, Here's a table that gives recommended gauge >>>with regard to frequency. >>>See Table B. >>> http://www.litz-wire.com/technical.html >>>Same thing in pdf. >>>http://www.litz-wire.com/New%20PDFs/Frequency_Chart_3.01.13.09.pdf >>> >>>Regarding "ANY specialized, presumed to be required braiding or weaving": >>>This is used to equalize proximity effects which equalizes currents in the >>>individual wires. >>> >>>Quote from; http://www.dartmouth.edu/~sullivan/litzwire/skin.html >>>"The objective of twisting or weaving litz wire, as opposed to just grouping >>>fine conductors together, is to ensure that the strand currents are equal. >>>Simple twisted bunched-conductor wire can accomplish this adequately in >>>situations where proximity effect would be the only significant problem with >>>solid wire. Where skin effect would also be a problem, more complex litz >>>constructions can be used to ensure equal strand currents. Thus, in a >>>well-designed construction, strand currents are very close to equal." >>> >> >>Yup. He's AlwaysWrong. >> >>John > > You're a goddamned retard, Larkin. As we all know, you're AlwaysWrong. John
From: life imitates life on 20 Feb 2010 14:10 On Sat, 20 Feb 2010 12:04:21 -0600, Tim Wescott <tim(a)seemywebsite.com> wrote: >On Sat, 20 Feb 2010 05:38:23 -0800, dcaster(a)krl.org wrote: > >> On Feb 20, 5:47�am, life imitates life >> <pastic...(a)thebarattheendoftheuniverse.org> wrote: >>> On Fri, 19 Feb 2010 16:58:13 -0600, Tim Wescott <t...(a)seemywebsite.com> >>> wrote: >>> >>> >>> >>> >On Fri, 19 Feb 2010 16:18:49 -0600, Tim Williams wrote: >>> >>> >> "George Herold" <ggher...(a)gmail.com> wrote in message >>> >>news:550831a9-5935-4e3d-b37e- >c664ebd9d752(a)o3g2000yqb.googlegroups.com... >>> >>> We get Litz wire from MWS but nothing that big. �If you don't need >>> >>> that much have you thought of 'rolling your own'? >>> >>> >> I do sometimes, but only for small things. �I'm contemplating 10A at >>> >> 1MHz, so it needs to be pretty fine = way more strands than I'd want >>> >> to deal with. >>> >>> >> I actually have some copper rope, which is about 1/4" diameter and >>> >> looks to be made of 28AWG or so. �I don't remember how many strands >>> >> it is, but if I guess the rope is wound from 7 strands of 31 strand >>> >> twist, that's 7*31 = 217. �If 28AWG is good for ~200mA, 217 strands >>> >> should be good for 40A, which sounds about right, I'd call it 8 or >>> >> 10AWG equivalent. �I salvaged this stuff from some old motor driver, >>> >> which used a spool of this stuff for air-core inductors. >>> >>> >> Tim >>> >>> >Isn't there some magic braiding pattern for Litz wire? >>> >>> � No. �The wire strands have to be mag wire, which segregates them >>> � from >>> each other, allowing the skin effect to be taken advantage of. �Without >>> strand segregation, it becomes a single strand, from the POV of the >>> current flowing in it, with only one skin for the entire mass. >> >> No again. The wire strands have to be segregated and also braided so >> that some of the time a strand is on the outside of the bundle and >> sometimes on the inside of the bundle. See attached from Wiki. >> >> Litz wire uses some different tricks. Instead of using one big >> conductor, it uses lots of little conductors (strands) in parallel >> (forming a bundle). Each little conductor is less than a skin-depth, so >> an individual strand does not suffer an appreciable skin effect loss. >> However, that is not the complete story. The strands must be insulated >> from each other -- otherwise all the wires in the bundle would short >> together, look like a single large wire, and still have skin effect >> problems. Furthermore, the strands cannot occupy the same radial >> position in the bundle: the electromagnetic effects that cause the skin >> effect would still disrupt conduction. The bundle is constructed so the >> individual strands are on the outside of the bundle (and see low >> resistance) for a time, but also reside in the interior of the bundle >> (where the EM field changes are the strongest and the resistance is >> higher). If each strand sees about the same average resistance, then >> each strand will contribute equally to the conduction of the entire >> cable. > >Why, then, does it work to make up multi-strand wire bundles for SMPS >service where the wires are just lightly twisted into a bundle? Are >these getting one part of the way there, but not all? Yes. Depending on the gauge, woven will perform better, but ANY configuration that splits up the current flow into smaller diameter runs is going to yield some litz effect and will definitely be better than a single solid strand of equivalent gauge for both transformer operational efficiency, as well as current handling capacity. > >I had heard about the Litz wire 'gotta be a magic braid pattern', but >then I've seen all these SMPS transformers that just have almost-parallel >strands. I obtained huge improvements, and the use of pro grade "real" litz would have only improved it a slight bit more.
From: life imitates life on 20 Feb 2010 14:12 On Sat, 20 Feb 2010 12:16:04 -0600, "amdx" <amdx(a)knology.net> wrote: > It's just a matter of good, better, and best. >Best would be properly braided* and would have the least AC resistance. > Mike >*I'm not sure braided is the proper term. Each wire needs to have equal >exposure to all positions in the bundle. Please tell this to the Larkin retard that attacked me after your last post.
From: amdx on 20 Feb 2010 14:27 "life imitates life" <pasticcio(a)thebarattheendoftheuniverse.org> wrote in message news:evc0o5t3pbvt7372jcbj7n283n2fcelolo(a)4ax.com... > On Sat, 20 Feb 2010 12:16:04 -0600, "amdx" <amdx(a)knology.net> wrote: > >> It's just a matter of good, better, and best. >>Best would be properly braided* and would have the least AC resistance. >> Mike >>*I'm not sure braided is the proper term. Each wire needs to have equal >>exposure to all positions in the bundle. > > > Please tell this to the Larkin retard that attacked me after your last > post. Please reread my last response to you, 2-20 7:33am that was a rebuttal (attack) on your 2-20 12:06am post. I see someone used the term woven, maybe a better term than braided? Mike
From: amdx on 20 Feb 2010 14:31
"life imitates life" <pasticcio(a)thebarattheendoftheuniverse.org> wrote in message news:dlc0o5d79sckha2l6lqqa6090aba6eqkfd(a)4ax.com... > On Sat, 20 Feb 2010 12:04:21 -0600, Tim Wescott <tim(a)seemywebsite.com> > wrote: > >>On Sat, 20 Feb 2010 05:38:23 -0800, dcaster(a)krl.org wrote: >> >>> On Feb 20, 5:47 am, life imitates life >>> <pastic...(a)thebarattheendoftheuniverse.org> wrote: >>>> On Fri, 19 Feb 2010 16:58:13 -0600, Tim Wescott <t...(a)seemywebsite.com> >>>> wrote: >>>> >>>> >>>> >>>> >On Fri, 19 Feb 2010 16:18:49 -0600, Tim Williams wrote: >>>> >>>> >> "George Herold" <ggher...(a)gmail.com> wrote in message >>>> >>news:550831a9-5935-4e3d-b37e- >>c664ebd9d752(a)o3g2000yqb.googlegroups.com... >>>> >>> We get Litz wire from MWS but nothing that big. If you don't need >>>> >>> that much have you thought of 'rolling your own'? >>>> >>>> >> I do sometimes, but only for small things. I'm contemplating 10A at >>>> >> 1MHz, so it needs to be pretty fine = way more strands than I'd want >>>> >> to deal with. >>>> >>>> >> I actually have some copper rope, which is about 1/4" diameter and >>>> >> looks to be made of 28AWG or so. I don't remember how many strands >>>> >> it is, but if I guess the rope is wound from 7 strands of 31 strand >>>> >> twist, that's 7*31 = 217. If 28AWG is good for ~200mA, 217 strands >>>> >> should be good for 40A, which sounds about right, I'd call it 8 or >>>> >> 10AWG equivalent. I salvaged this stuff from some old motor driver, >>>> >> which used a spool of this stuff for air-core inductors. >>>> >>>> >> Tim >>>> >>>> >Isn't there some magic braiding pattern for Litz wire? >>>> >>>> No. The wire strands have to be mag wire, which segregates them >>>> from >>>> each other, allowing the skin effect to be taken advantage of. Without >>>> strand segregation, it becomes a single strand, from the POV of the >>>> current flowing in it, with only one skin for the entire mass. >>> >>> No again. The wire strands have to be segregated and also braided so >>> that some of the time a strand is on the outside of the bundle and >>> sometimes on the inside of the bundle. See attached from Wiki. >>> >>> Litz wire uses some different tricks. Instead of using one big >>> conductor, it uses lots of little conductors (strands) in parallel >>> (forming a bundle). Each little conductor is less than a skin-depth, so >>> an individual strand does not suffer an appreciable skin effect loss. >>> However, that is not the complete story. The strands must be insulated >>> from each other -- otherwise all the wires in the bundle would short >>> together, look like a single large wire, and still have skin effect >>> problems. Furthermore, the strands cannot occupy the same radial >>> position in the bundle: the electromagnetic effects that cause the skin >>> effect would still disrupt conduction. The bundle is constructed so the >>> individual strands are on the outside of the bundle (and see low >>> resistance) for a time, but also reside in the interior of the bundle >>> (where the EM field changes are the strongest and the resistance is >>> higher). If each strand sees about the same average resistance, then >>> each strand will contribute equally to the conduction of the entire >>> cable. >> >>Why, then, does it work to make up multi-strand wire bundles for SMPS >>service where the wires are just lightly twisted into a bundle? Are >>these getting one part of the way there, but not all? > > Yes. Depending on the gauge, woven will perform better, but ANY > configuration that splits up the current flow into smaller diameter runs > is going to yield some litz effect and will definitely be better than a > single solid strand of equivalent gauge for both transformer operational > efficiency, as well as current handling capacity. >> >>I had heard about the Litz wire 'gotta be a magic braid pattern', but >>then I've seen all these SMPS transformers that just have almost-parallel >>strands. > > I obtained huge improvements, and the use of pro grade "real" litz > would have only improved it a slight bit more. Can you quantify that? What frequency? What size wire? How many in the bundle? What was the original single wire design size? And what do you mean by huge improvements? Is this a Q measurement or a reduction of heat. Mike |