In case (b) of this clause, I do not understand how the decisive voltage (classification) is to be correctly calculated. For those of you who have the standard, try using (for example) Udc = 30 V and Udcp = 35. The method outlined in the standard (with the formula given) will indicate that in this case, Um is 2000 Vdc.
For a voltage Udc = 200 V, Udcp = 205, the method will indicate that the circuit lies in the Um = 120 V category. Either I am missing part of the "picture", or there is something wrong with the way that the formula is laid out. Hopefully somebody can make this clear for me. Arjen
