All, IEC60950-1 Section 2.2.3 specifies that SELV circuits are required to remain below 60Vdc in single fault conditions. Section 1.4.14 specifies functional and basic insulation must be shorted when single faults are simulated. This leads to believe that in some cases it may be required to provide reinforced insulation between earthed SELV circuits and unearthed SELV circuits. For example, if an unearthed SELV circuit of +40Vdc referred to an operator accessible floating logic ground is shorted to an earthed SELV circuit of -54Vdc, the floating logic ground could reach -94Vdc which exceeds SELV limits. On another hand, at the very beginning of Table 2G, it is specified that only functional insulation is required between unearthed SELV and earthed SELV circuits. Which is right? Did I miss something? Thanks, Eric
Éric Meunier Designer EMC/Environmental E-mail: <mailto:[email protected]> [email protected] Kontron Canada Inc. 616, rue Curé-Boivin Boisbriand, Québec Canada, J7G 2A7 Tel: 1-450-437-4661 ext. 2419 Fax: 1-450-437-8053 L'information contenue dans le présent document est la propriété de Kontron Canada inc. et est divulguée en toute confidentialité. Cette information ne doit pas être utilisée, divulguée à d'autres personnes ou reproduite sans le consentement écrit explicite de Kontron Canada inc. The information contained in this document is confidential and the sole property of Kontron Canada Inc. It shall not be used, disclosed to others or reproduced without the express written consent of Kontron Canada Inc. ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
