The voltage withstand value specified in the current version of transformer Standard IEC 61558 is smaller than that of IEC 60317-0-7 because

●IEC 60317 is calculated using the thickness of double sided insulation (finished outer diameter - bare wire diameter). However, IEC 61558 is calculated based on the thickness of single side insulation ((finished outer diameter - bare wire diameter) / 2), so the breakdown voltage value of IEC 61558 is only half of that of IEC 60317-0-7.

●The specific withstand voltage values per micron are: measured at 180 ° C according to IEC 60317-0-7 and IEC 61558, and measured at room temperature according to IEC 60317-0-7. The actual working temperature of switching power supply is between room temperature and 180 ° C.

●For the calculation of breakdown voltage, IEC 60317-0-7 takes the average value of the finished outer diameter tolerance, while IEC 61558 takes the maximum value of the outer diameter tolerance for calculation. This makes the value of IEC 61558 slightly higher.