A combined measuring and detection system is disclosed which includes an electronic evaluation unit for analyzing a broad frequency spectrum of measured quantities and one or more measuring devices for measurement of one or more of a magnetic field, an electric field, a current, and a voltage. The measuring devices are operatively connected to the electronic evaluation unit, which is provided with at least one frequency splitter dividing the measured quantities into a low frequency component and into a high frequency component. Low frequency components are used for measurement and protection analysis and high frequency components are used to detect partial discharges activity.