Process for identification of the direction of rotation of two periodic electrical signals at the same frequency

A process and apparatus for identification of the direction of rotation of two periodic electrical signals present on two electrical conductors, particularly of a three-phase power system. In this process, the signals are sampled from two conductors by two wires of the test apparatus provided with a connection to ground via a user of the apparatus. The direction of rotation is determined from information provided by the two signals. The direction of rotation is determined during the zero-crossing of the voltage between the two phase signals. The invention can be used in a apparatus for testing of the direction of rotation of the phases of a three-phase network.