Rating the dielectric withstand of equipment is based on the expected dielectric stresses. This is a combination of the stress caused by the power-frequency continuous
voltage and the stress caused by the mostly short-term overvoltages. The insulation coordination for power-frequency continuous voltages ≤1 kv is based on DIN VDE
0110 and DIN VDE 0109 (currently still in draft form). In the case of voltages > 1 kV the specifications in DIN EN 60071-1 (VDE 0111 Part l) and the application guide in
DIN EN 60071-2 (VDE 0111 Part 2) apply.