Peter, Thank you for your help. Actually you've helped me two things, they are the Nomex thickness in microwave oven transformers and here again in UL 1950. Thks.
Robin Chan. >From [email protected] Wed Dec 16 21:33:01 1998 >Received: from [209.88.190.98] by hotmail.com (1.0) with SMTP id MHotMail30913255715046843506532474351225405037180; Wed Dec 16 21:33:01 1998 >Received: from peter ([209.88.190.101]) by nt-server.itl.co.il > (Netscape Mail Server v2.02) with SMTP id AAC94; > Thu, 17 Dec 1998 07:37:59 +0200 >From: [email protected] (Peter Merguerian) >To: [email protected], > [email protected], > "robin chan" <[email protected]> >Date: Thu, 17 Dec 1998 07:25:38 +0200 >MIME-Version: 1.0 >Content-type: text/plain; charset=US-ASCII >Content-transfer-encoding: 7BIT >Subject: Re: Triple insulated wires in UL 1950 >CC: [email protected] >Priority: normal >In-reply-to: <[email protected]> >X-mailer: Pegasus Mail for Win32 (v3.01b) >Message-ID: <19981217053753934.AAC94@peter> > >Dear Robin, > >I hope you have your UL1950 standard since I will refer you to >some important clauses which will help you a lot. The following >serves to respond to your questions: > >1. Creepage is defined in clause 1.2.10.1 as "the shortest path >between two conductive parts, oe between a conductive part and >the BOUNDING SURFACE of the equipment, measured along the >surface of the insulation". > >Bounding Surface is defined in clause 1.2.10.3 as "the outer >surface of the ELECTRICAL ENCLOSURE, considered as though >metal foil were pressed in contact with accessible surfaces of >insulating material". > >Electrical Enclosure is defined as ............ I give up since I can go >on and on and on! > >Also, refer to Annex F which gives some good examples for >creepages and clearances. > >2) Need more information on how transformer is being used before I >can answer the question. What type of circuit do you have in the >primary and secondary winding(s) (hazardous primary, hazardous >secondary, SELV, ELV). Are these circuits reliably earthed or >unearthed? What are the voltages involved between the primary and >secondary windings? > >3) TIW is a copper magnet wire with three ultra thin layers of >insulation. The wires that I came across have been both UL >Recognized and TUV Approved and have been investigated to >comply with clause 2.9.4.2 and/or 2.9.4.4 of the standard >(exemption for 0.4 mm thick insulation requirement for reinforced or >supplementary insulation in 2.9.4.1). > >4) I can't tell you about costs but I am seeing more and more >constructions of switching power supplies using TIW - I can only >assume it is cheaper to use in large production runs. The other >advantage is that you do not have to use margin tape or other >insulating tape. For example, between a hazardous primary >winding (copper magnet wire only) and an unearthed SELV winding >(TIW) no additional insulation is needed (assuming the TIW was >previously investigated for reinforced insulation in clauses 2.9.4.2 >and/or 2.9.4.4 of the standard. The other advantage is safety >engineers at the various test labs who hate to dissect transformers >love looking into transformers with TIW! > >5) Quantum shield? Doesn't seem to be TIW. > >Hope the above helps. > > > > > >> Dear all, >> >> We have designs for ferrite transformers need to be compliant >> to UL1950. However, some concepts still confused me, >> >> (1) How do UL define the creepage distance? >> (2) We use marginal tapes for the primary winding and >> the interwinding also. Then do we need to add >> marginal tapes for the secondary winding? >> (3) What is triple insulated wire? What are the >> critical electrical properties for this wire? >> (4) If triple insulated wires are used, what is the >> advantages? >> (5) Phelps Dodge has got a wire called TZQS wires (wire >> with quantum shield), is it a triple insulated wires. >> >> Many thanks >> >> Robin Chan >> >> >> ______________________________________________________ >> Get Your Private, Free Email at http://www.hotmail.com >> >> --------- >> This message is coming from the emc-pstc discussion list. >> To cancel your subscription, send mail to [email protected] >> with the single line: "unsubscribe emc-pstc" (without the >> quotes). For help, send mail to [email protected], >> [email protected], [email protected], or >> [email protected] (the list administrators). >> > > >PETER S. MERGUERIAN >MANAGING DIRECTOR >PRODUCT TESTING DIVISION >I.T.L. (PRODUCT TESTING) LTD. >HACHAROSHET 26, P.O.B. 211 >OR YEHUDA 60251, ISRAEL > >TEL: 972-3-5339022 >FAX: 972-3-5339019 >E-MAIL: [email protected] >Visit our Website: http://www.itl.co.il ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
