Current editions of UL 1950/CSA 22.2 No. 950 (3rd Ed) and EN 60950 (2nd Ed 4th Amd) would require BASIC INSULATION (see 6.2.1.2) between TNV-2 & SELV.
I believe that a working voltage of 150VDC (Max TNV + some left over on SELV side) and 200Vpk (ringing) is generally accepted as the working voltage between TNV-2 & SELV. At least this works for the labs I talk to. (UL is a bit different here, as TNV limits are lower). 150VDC would determine CREEPAGE DISTANCE, 200Vpk CLEARANCE: Table 6: (CREEPAGE, 150VDC, MG III) = 1.6mm - for the US this may be reduced to 1.5mm as the TNV limits are lower. Table 5: (CLEARANCE, 200Vpk, PD 2) = 0.9mm (Mains supply < 150Vrms) Table 5: (CLEARANCE, 200Vpk, PD 2) = 1.0mm (150Vrms<Mains Supply<300Vrms) As Helmut indicated below, BASIC INSULATION (clause 6.2.1.2) may not be required if your SELV ckt has a PE connection...but this, of course, may not be acceptable in all countries... Also, I do not know that anyone (CB's at least) is testing to IEC 60950 yet? Let me know if I'm wrong on this.. Regards, Mel Pedersen, Midcom Inc. mailto:[email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Friday, June 16, 2000 1:34 AM To: [email protected]; [email protected] Subject: AW: TNV-2 to SELV Spacing Gary, between TNV2 and PE (ground) the only requirement is functional insulation. For max TNV2 (120Vdc) the following spacings apply: clearance: 0,6mm (table 2K last column) creepage: 0,6 up to 2,4mm depending on the PD and MG (table 2L) eg for PD 2 MG IIIa 1,5mm relevant document: IEC 60950 3.ed 1999 best regards helmut hintz ---------- Von: Gary.McInturff / unix ([email protected]) An: [email protected] Betreff: TNV-2 to SELV Spacing Datum: Donnerstag, 15. Juni 2000 16:44 Temporarily without my standard, and need a spacing requirement. Seems to me that over surface it was 1.4 mm or 1.0 mm through air, but it also seems to me that it was contingent upon whether or not the secondary was grounded or not. How about TNV-2 to ground? As always there is no room, no time and we need to spin the board. Thanks Gary ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
