Thanks, guys!
I have not received a fully explanation from the safety lab, but I assume they are concerned about this: * With only one insulation layer between Prim/Sec winding in the transformer, a fault in the insulation tape will result in 230VAC in the secondary circuits. OK, but there are no cable interfaces on the secondary side and no conductive parts. The entire enclosure is flame category V-1 or V-0. But one part of the enclosure is a little piece that is pressed onto the main part of the enclosure. This little part can be demounted, and since the product is plugged into a 230VAC socket that is located 20 cm above the floor, a child could manage to remove this little part and access the secondary circuit (now 230VAC) by its fingers. I guess this is the reason for requiring two layers in the transformer. Or make it impossible to remove this part which can give access to secondary circuits. Best regards Amund Fra: Richard Nute Sendt: 16. februar 2022 23:09 Til: 'Amund Westin' <[email protected]>; [email protected] Emne: RE: [PSES] Numbers of insulation layers in transformer (IEC62368) Hi Amund: Since the unit does not have grounding/earthing, it is therefore double-insulated with respect to the input 230 volts (and must bear the double-insulated symbol). This requires all accessible conductive parts and accessible surfaces to be double-insulated from the 230 volts. If the secondary circuit has any accessible conductive parts (e.g., metal antenna), then the secondary must be double-insulated from the 230 volts: transformer must have two insulation layers, basic and supplementary. (This is the most common construction.) If the secondary has no accessible conductive parts, then the insulation between the secondary and accessible surfaces (whether or not conductive) is "supplementary insulation": transformer can have one insulation layer, basic. (This is uncommon construction and will likely be not acceptable to many certification houses.) Good luck, and best regards, Rich From: Amund Westin <[email protected] <mailto:[email protected]> > Sent: Wednesday, February 16, 2022 1:02 PM To: [email protected] <mailto:[email protected]> Subject: [PSES] Numbers of insulation layers in transformer (IEC62368) Do I need one or two insulation layers (tape) between the primary and secondary windings? Can find an absolute answer in the standard IEC62368. Product: Input 230VAC Secondary 24VDC for other Low volt circuits No grounding /earthing No cable outputs Plastic enclosure Radio HUB product Thanks. Best regards Amund - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
