Transformer insulateing tape?
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From: Jan Panteltje on 20 Jun 2010 12:04 On a sunny day (Sun, 20 Jun 2010 11:19:26 -0400) it happened Hammy <spam(a)spam.com> wrote in <f2cs16t8rhf6nbf5b1i2jge90dn6tvtk4j(a)4ax.com>: >On Sun, 20 Jun 2010 14:57:32 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>On a sunny day (Sun, 20 Jun 2010 07:43:29 -0700 (PDT)) it happened Proteus IIV >><proteusiiv(a)gmail.com> wrote in >><8316ba75-68e0-4f76-96fd-04cbc92ddbb8(a)u26g2000yqu.googlegroups.com>: >> >>>I AM PROTEUS >> >>An other Apple user flips out. >> >>FYI Steve Jobs wil die one day. > >Yep there is a reason I KF anything from google groups to much spam >and nutjobs. I rarely see any spam or wackos unless someone quotes >them. There are some decent posters from google but far and away the >junk is ridicoulous. I dont know how anyone can even keep track of >anything in GG it gets spam bombed several times a day. > >Their is already enough borderline wackos here I can live without a >further contribution from Google. > Sorry, I did see a whole lot of 'I AM PROTEUS' replies and could not resist. To stay on the (original) subject, I remember one word from my transformer factory days: Melinex. That said, I have wound a TV hor output transformer with normal A4 paper as isolation. As long as temperature stays low, and it does not get wet, it works. I am not sure if you can get Melinex in low quantities.
From: Archimedes' Lever on 20 Jun 2010 12:16 On Sun, 20 Jun 2010 07:57:36 -0400, Hammy <spam(a)spam.com> wrote: >On Sun, 20 Jun 2010 06:07:33 +0000 (UTC), Cydrome Leader ><presence(a)MUNGEpanix.com> wrote: > > >> >>This info helps quite a bit. >> >>For a single unit you might be able to scavenge the yellow tape from a >>junked switching power supply from from a computer. Some peel apart if you >>smash the ferrite, some don't. Do avoid plain electrical tape- it creeps >>and "pressure" inside a coil with hundreds or thousands of turns can sink >>right though it. >> >>Other sources of insulating material are in your junk pile. Those white >>plastic sheets that replace fish paper to keep pins from hitting close >>fitting chassies can be cut up and used. Junked computer power supplies >>have lots of goodies like this inside them. >> >>It works fine for quick and dirty projects. secure it with scraps whatever >>tape you can peel from a transformer or inductor and you're good. > >Thanks for the suggestion. > > I have two boxes of junk I can dig through. This is likely what I'll >do next order to Newark I 'll get the proper tape for future projects. You can find stuff like this at an industrial liquidator shop, if there is such an animal as that in your town. In this area, there are several. Suprizingly, old mil surplus shops can also have raw goods.
From: Bill Sloman on 20 Jun 2010 12:16 On Jun 20, 5:47 am, Archimedes' Lever <OneBigLe...(a)InfiniteSeries.Org> wrote: > On Sat, 19 Jun 2010 20:08:16 -0700 (PDT),Bill Sloman > > <bill.slo...(a)ieee.org> wrote: > >The polyester backing film is nominally 1 mil thick, but with the > >adhesive it builds up to 2.5 mils - nominally 63.5 microns. We used it > >between layers of round wire, so presumably some of the adhesive was > >squeezed sideways into the gaps between the wires. > > Nope. Plenty of variations about. The specific tape that I was talking about is a 1 mil thick film with a 1.5 mil layer of adhesive, as specified in the data sheet for which I gave the URL (which you have snipped). Since the data sheet also lists a thicker variant of the same tape, you aren't telling me anything I didn't know. Since the OP was asking for material that he could buy off the shelf and in small quantities, the availability of thicker and thinner tapes that you can only order in volume from specialised distributoers who mostly don't hold stock isn't of that much relevance to this thread. > I had a lot of .5 mil tape with .5 mil adhesive. But where can we get it? Off the shelf and in small quantities? > The taut use of the tape will cold flow it as far into any crevices it > can. Then baking 'relaxes' it 'in' further. Sure. -- Bill Sloman, Nijmegen
From: Archimedes' Lever on 20 Jun 2010 12:29 On Sun, 20 Jun 2010 05:24:54 -0700 (PDT), Wimpie <wimabctel(a)tetech.nl> wrote: >On 20 jun, 13:40, Archimedes' Lever <OneBigLe...(a)InfiniteSeries.Org> >wrote: >> On Sun, 20 Jun 2010 04:19:37 -0700 (PDT), Wimpie <wimabc...(a)tetech.nl> >> wrote: >> >> >> >> >On 19 jun, 18:50, Hammy <s...(a)spam.com> wrote: >> >> What kind of tape can you use for insulation between primary to >> >> secondary of flyback transformer. I know mass produced professional >> >> designs use a 3M specialty tape. What I'm looking for is a tape I >> >> could pick up at Staples or some office supply store or hardware >> >> store. >> >> >> The vinyl electrical tape I can find is only rated for 600V and 80C >> >> MAX TEMP. >> >> >> Is there a commonly available tape that is good for higher temp and >> >> offers higher insulation? I've read of people using a mylar tape is >> >> there a brand name ,type anyone could recommend? >> >> >> This is for a 90 - 140Vac input flyback. >> >> >Hello, >> >> >A flyback needs low spreading inductance (to avoid excessive loss in >> >the snubber). You don't want large barrier between your windings. >> >Don't trust hobby tape, but try to get polyimide tape (brand name >> >Kapton). It isn't cheap, but does the job. >> >> >Best regards, >> >> >Wim >> >PA3DJS >> >www.tetech.nl >> >without abc, PM will reach me >> >> � Kapton is usually too thick and is cumbersome to wind with. �the tapes >> that have been suggested are the right tapes to use. �Polyester tapes >> will get the windings as close together as they can be. > >Hello Archimedes' Lever, > >I assumed that he needs the tape to separate primary and secondary >windings only. For example: > >First half of primary turns in a layer > two/three layers tape for safety insulation >complete secondary winding > two/three layers tape for safety insulation >second half of primary turns in the last layer. > And why is it you wish to split the primary winding and place half UNDER the secondary, and half OVER the secondary? >In such an arrangement, kapton / polyimide is not that difficult to >use (from experience), Kapton is only feasible on larger form factors. If this is a small pot core it will not be as easy to use kapton, and Kapton does not"sink in" it stays flat, which defeats your original suggestion that they be nested as tightly together as they can. The poly tape has just as good electrical resistance, and takes up far less bobbin space. The stuff is just too inflexible for smaller applications. I have used it on say a 1.5" dia pot core, but it only had a few primary turns and they were inside a Teflon tube already and wound flat, so the Kapton fell on top of it flat. I doubt he will get the same winding profile with 3 x #30. > however I fully agree that suitable polyester >tape can do the job (cheaper, easier to work with and easier to >get). Not to mention the way the industry does it in nearly every case. > The reason for mentioning the polyimide was that he can be >almost sure to have something that is OK. If the step up is not that much, he is sure to be OK with cheap xformer tape too. > >Before making final decision, he also has to find out the expected >over voltage category and whether he requires single or double/ >reinforced safety barrier in his transformer (as this also determines >the required clearance and creepage distance). He mentioned 12V and 5V, so I do not think he is doing an HV application, and he could probably get away with zero transformer tape using simple double strength mag wire. Granted I would still separate primary from secondary, but I doubt he needs to worry about creepage distances in such a LV application. He is already isolated from the AC line. If there is bobbin space, I would do things like switching to say 3 x #28 if it fits. Or two flat wound. He gave a lot of info, but there were still a couple details to talk about.
From: krw on 20 Jun 2010 12:51
On Sun, 20 Jun 2010 08:43:34 -0700 (PDT), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Jun 20, 5:25�pm, Fred Abse <excretatau...(a)invalid.invalid> wrote: >> On Sat, 19 Jun 2010 20:08:16 -0700,Bill Slomanwrote: >> > The electronics industry is infested with dimensions expressed in >> > bizarre fractions of an inch >> >> Commonly: >> 0.1 >> 0.05 >> 0.001 >> >> This must be a usage of the word "bizarre" with which I am as yet >> unfamiliar. > >As an occasional woodworker, I understand half inch and quarter inch >thicknesses, and I've used veneer that was just one sixty-fourth of an >inch thick. Decimal divisions of the inch strike me as odd - if you >want to use decimal arithmetic, metric units make a lot more sense. SLowman, stupid as ever. The 'mil' is a quite standard unit of measure, and yes, it's used by woodworkers, too. |