Alexandru - You have received several good answers. I would add the following.
To Rich Nute's descriptor of "active devices," add, "nonlinear devices," to those types of components not acceptable for use in place of insulation. This would expand the scope to include gas tube and other voltage surge suppressors, fuses and the like. Keep in mind that Double Insulation can be achieved by two separate pieces (or collections) of insulation. For instance, one transformer provides Basic Insulation and another Supplementary Insulation. Since you claim to have ELV, there is the presumption that you have at least Basic Insulation from Primary and Hazardous Voltage circuits. Addition of a second bit of Basic Insulation gets you close to your goal, but not quite. If you can demonstrate that either or both of the two bits of Basic Insulation also comply with the additional requirements for Supplementary Insulation, then you've achieved your goal, since Double Insulation is equivalent to Reinforced Insulation. If you wish to take transients into account for reduction of Clearance Distances, you may refer to ยง2.10.3 and Annex G. This doesn't work for Creepage Distances. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA [email protected] > -----Original Message----- > From: Alexandru Guidea > Sent: Tuesday, May 06, 2003 9:47 AM > > Dear colleagues, > > As part of a PCB design required to be compliant > with EN60950, we want to > use the configuration described below, to be able > to relax the traces > separation. The circuit intended to become SELV > is accessible to the > operator. > > Questions: > 1. Is the combination of Basic Insulation + > Fuse&Transorb(15V) equivalent to > Reinforced Insulation? > 2. Does the transorb have to comply with a > specific EN safety standard (like > one applicable to Y caps)? > > Thanks, > > Alexandru Guidea > > CAE Inc. > Canada > > Basic > Insulation > | > | > ELV--------||-------FUSE--------------SELV (??) > | T > | R > A > N > S > O > R > B > | > | > GND (EARTH) This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
