An electric power system comprises recording devices (101-105) located at different elements of the electric power system and configured to record waveform samples of quantities related to operation of the elements of the electric power system. The electric power system comprises a central device (106) configured to receive the recorded waveform samples from the recording devices. The recording devices are synchronized to maintain a common clock time and to associate, to each of the recorded waveform samples, one or more timing values indicative of the clock time during recording the waveformsample. As the timing values are associated to the waveform samples, it is possible to reconstruct a time order of phenomena indicated by the recorded waveform samples. Thus, it is possible to identify which of the phenomena are causes and which are consequences when analyzing for example what happened prior to a fault situation.