Hi Peter,
The original discussion was based on the linear transformer. But what working voltage for barrier after 60950 switching power supply should be?
60950 power supply can provide one MOPP only, the insulation, after such SPS, between secondary and applied part should therefore meet one MOPP at least. For SPS, the measured working voltage between pri and sec is 350Vrms/ 670Vpeak, in this case. For barrier after the SPS, I think 240V reference voltage is appropriate. Because if pri shorts to sec, the switching circuit will be destroyed. That means 350Vrms/ 670Vpeak will die.
If I got something wrong, please correct me. Thanks.