Dear Robert, -48 Vdc supplied by CO may be considered as SELV if tolerance is up to 60 Vdc as in most COs in North America. In Europe and some other countries, CO supply tolerance exceeds 60 Vdc and could reach 72 Vdc. In this case, dc supply is considered as a secondary hazardous voltage cricuit or in some countries, like Germany, the supply may be considered a TNV-2 circuit.
Happy New and Safe Year to All > Hello All, > I have a question about classifying the CO power environment: > Would one consider the -48VDC power supplied by the CO to be a SELV > circuit as defined in EN60950/UL1950 etc? > How is the DC circuit isolated from the mains supply? > Thanks in advance, and > Happy Holidays, > Bob Tims > Compliance Engineer > Ericsson Messaging Systems Inc. > robert.t...@ericsson.com > 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
