High voltage spark over can be used in a controlled way. A spark over from a special electrode to a ground reference can be detected and evaluated. Perforations in plastic webs and products can be detected and counted. A High voltage generator provides the hardware and software to generate a controlled spark over, detect this and evaluate the spark over to produce a pulse signal. The pulse signal is available on the output connector and can be used for detecting spark-overs and thus perforations in materials.