For power capacitor life time tests according to IEC61071 there is the need to apply AC and DC voltage at the same time. For power capacitors this is a quite challenging task because of the high currents and voltages. Two power supplies are needed, they need to be decoupled and adjusted separately. During life time test the test object may have a breakdown or short circuit, the system must be able to handle these failures without damage. The stored energy is very high and dangerous, it must be discharged to keep the operation safe.