I do not know anything about this topic, that's why I asked. I was told by a friend that the Low Voltage Directive in the EN61010 standard was the right place to look for answers, so I did and found some details but I do not understand it all. I found this http://www.ni.com/white-paper/2827/en/ which talks about instruments and isolation, which is interesting as it also mentions transformers and the categories used. So I emailed two transformer manufacturers and the Swedish National Electrical Safety Board and asked them about the use of transformer winding usage and also asked my insurance company.
One transformer manufacturer answered me that as long as the combined voltage of the secondary plus primary winding is within the isolation category, and voltage for the primary isolation barrier, it would of course work and be within the approval limits but they did not recommend it for a few reasons, the foremost reason being that a transformer is not tested for this connection and it would probably fail (not due to the voltages used but more so because there is no test for this condition) in an approval test under this condition and/or at least need an expensive new way of testing to be performed for an approval - being within the approval limits is not the same as being approved when used in a way that the approval testing has not tested nor taken into account they told me. One other reason for not using this way of connecting the windings is because the heating of the transformer windings in this condition is not taken into consideration when the transformer is designed and that could affect performance. When it comes to the insurance question it would not be ok if it did not have an approval and was the starting cause for the fire, if it had an approval it would be just fine. So, it will probably work ok but it might be hard to get an approval and therefore not good to use if it catches fire, at least in Sweden and with my insurance company. So I'll stick with transformer bought from reliable transformer manufacturers for now. /Martin -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/df368542-835c-4b09-86d6-40640cf80e4e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
