The present invention relates to a simple and reliable device for recognizing disruptions in an on-board power supply. The device comprises a reception unit adapted to receive a first and a second temporal sequence of measurement values, the measurement values of the first sequence being measured at a first measuring point of the on-board power supply and the measurement values of the second sequence being measured at a second measuring point of the on-board power supply differing from the first measuring point, and the measurement values representing current or voltage values, and an evaluation unit adapted to recognize the occurrence of a disruption based on a comparison of the first dispersion of the measurement values of the first sequence and a second dispersion of the measurement values of the second sequence.