Robin, Your question consists of many parts and here is the answer to some of the parts.
UL and other agencies measure creepage/clearance using the working voltages in a few places mainly across the isolation barrier. You then use the peak and RMS values that you have obtained and then calculate the necessary cr/cl using the tables 3-6 section 2.9 in IEC950. The TIW, as its name implies has several layers of insulations and hence can be used as reinforced insulation where needed. One of the main advantages of TIW is that you don't need margin tape in your transformer. i.e you can wind the primary on top of the secondary without the use of interwinding tapes or margin tape and therefore gain more space on your bobbin. On the other hand the main disadvantage of TIW is its cost as it is more expensive than conventional magnet wires. As for Phelps Dodge wire that you mentioned, I suggest you contact the manufacture direct and ask for specification of this particular wire. When using TIW, all agencies test your transformer in accordance with Annex U of 950 I hope this help. Have a good Christmas Regards Homi Ahmadi Cortech Systems E-mail: [email protected] "robin chan" <[email protected]> on 12/14/98 11:34:50 AM Please respond to "robin chan" <[email protected]> To: [email protected], [email protected] cc: [email protected](bcc: Homi Ahmadi/CORTECH) Subject: Triple insulated wires in UL 1950 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). --------- 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).
