This invention concerns methods and devices for calibrating a partial discharge measuring device and for locating faults on cables. In the method, calibration signals, which can include a band-limited white noise, are used with a periodically repeated signal course. By averaging over a predetermined period duration (T) of the calibration signal, it is possible, in the case of a partial discharge measurement, to recalibrate the measuring device continuously during the measurement, and additionally on cables to determine the fault location with great precision.