The energy transition is characterized by a broad application of power electronic systems and components in power supply systems. The higher dynamics and flexibility of these systems also poses new challenges for high-voltage testing technology, which can also be advantageously solved by the use of power electronic actuators. Variable frequency converter based power supplies for high voltage test systems best meet technical and market requirements if they can be modularly adapted to different power classes and at the same time are cost neutral compared to conventional technology. A high test voltage quality, low electromagnetic emissions with respect to partial discharge measurements and low electromagnetic disturbances in the network are only some of the requirements, but their solution also represents an added value compared to conventional supplies for HV test systems. The article describes the changes of a cable test with a frequency converter based power supply. This supply replaces the classic actuator with improved performance. The implementation of the requirements is discussed and concrete measurement results of the test system are presented which prove the suitability and describe the advantages of the new inverter platform for high-voltage testing technology.