George, Do you have transient voltage surge supressors. Maybe this is why you failed the hipot. The standard allows you to pass the Impulse Test in lieu of hipot. Try this method.
Regarding insulation between TNV-3 and SELV/Earth the standard allows you the following alternatives routes to compliance: Min. Basic insulation (clearance/creepage) and the 6.4.1 tests (hipot or impulse). Installation by qualified personnel, permanent connection to earth instructions and the tests of 6.2.1.3 (surge test). However, please note that prior to the surge test, anything less than basic insulation on the board is shorted. By the way, a transformer is not always needed on a modem. The new design of modems have capacitors (not required to be Approved) between the TNV-3 and SELV. Hope this helps a little. Read your standard. You will find a statement which says "other solutions are possible". Therefore, you must discuss your problem with your friendly test lab. Best Regards, > > Hello Once Again .. Everyone, > > I have a modem product that failed the hipot requirement defined in > cls 6 of 950. My understanding is that an isolation xfmr between Telco & > SELV is needed and clearance from Telco & gnd is to be 3mm minimum. Does > anyone have any other general design guidelines that they can share on this > topic ? > > Also, Can anyone point me to any manufacturers app notes for > components used for telco isolation ? > > And if anyone can recommend any reading material, I'd like to read > up on these and other issues relating to compliance design aspects of Telco > circuits. > > > Thanks, > George > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > jim_bac...@monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (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: pe...@itl.co.il Visit our Website: http://www.itl.co.il --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
