A measuring arrangement acquires signals of alternating electrical magnitudes. A sampling apparatus performs a sampling of the signals to form digital sample values. A clock tracking apparatus adapts a sampling clock used by the sampling apparatus in the light of the frequency of the signal to be sampled. In order to be able to acquire reliably signals of alternating electrical magnitudes even when they have different frequencies, the sampling apparatus samples at least two of the signals each with its own sampling clock and the clock tracking apparatus adapts the sampling clock in the light of the frequency of the signal to be sampled simultaneously for each of these at least two signals. There is also described a corresponding method for measuring electrical signals.