- System for measuring the electrical power of the current flowing in at least one secondary electrical conductor (42A, 44A, 46A, 42B, 44B, 46B,..., 42N, 44N, 46N), the secondary conductor (42A, 42B,..., 42N; 44A, 44B,..., 44N; 46A, 46B,..., 46N) being electrically connected to a primary electrical conductor (34; 36; 38), the primary conductor (34; 36; 38) and the or each secondary conductor (42A, 42B,..., 42N; 44A, 44B,..., 44N; 46A, 46B,..., 46N) having substantially the same voltage (V1; V2; V3), with this measurement system comprising: - a primary module comprising a radioelectric emitter and a unit for measuring the voltage of the primary conductor (34, 36, 38), - at least one secondary module (62A,..., 62N) comprising a radioelectric receiver (80A,..., 80N), a sensor (76A,..., 76N) of the intensity (I1A, I2A, I3A, I1B, I2B, I3B,..., I1N, I2N, I3N) of the current flowing in the corresponding secondary conductor (42A, 44A, 46A, 42B, 44B, 46B,..., 42N, 44N, 46N) and a unit (126A,..., 126N) for calculating the electrical power (E 1, E 2, E 3, E 1 -, E 2 +, E 2 -, E 3 +, E 3 -) of said current flowing in the corresponding secondary conductor (42A, 44A, 46A, 42B, 44B, 46B,..., 42N, 44N, 46N), characterised in that - the primary module comprises first means of compression of the measured value of the voltage (V1, V2, V3) and means of emitting, from the radioelectric emitter to the radioelectric receiver (80A,..., 80N) of the or of each secondary module (62A, 62B,..., 62N), a first message containing the compressed value of the voltage measured by the unit for measuring, - the measurement system comprises means (106, 120A,..., 120N, 122A,..., 122N) for the temporal synchronisation of the or of each intensity sensor (76A,..., 76N) in relation to the unit for measuring voltage, and - the calculating unit (126A,..., 126N) is connected to the radioelectric receiver (80A,..., 80N) and able to calculate the electrical power from the value of the measured voltage (V1, V2, V3) received from the primary module and from the value of the intensity (I1A,..., I3N) measured by the intensity sensor (76A,..., 76N), and In that the first message comprises synchronisation data for the temporal synchronisation of the or of each intensity sensor (76A,..., 76N) in relation to the unit for measuring voltage, the date of reception of the first message being the date of reference for the synchronisation of the at least one first secondary module (62A,...,62N) in relation to primary module, the at least one first secondary module (62A,...,62N) being able to check that the first message contains the synchronisation data and to then carry out the temporal synchronisation with the primary module. - a primary module comprising a radioelectric emitter and a unit for measuring the voltage of the primary conductor (34, 36, 38), - at least one secondary module (62A,..., 62N) comprising a radioelectric receiver (80A,..., 80N), a sensor (76A,..., 76N) of the intensity (I1A, I2A, I3A, I1B, I2B, I3B,..., I1N, I2N, I3N) of the current flowing in the corresponding secondary conductor (42A, 44A, 46A, 42B, 44B, 46B,..., 42N, 44N, 46N) and a unit (126A,..., 126N) for calculating the electrical power (E 1, E 2, E 3, E 1 -, E 2 +, E 2 -, E 3 +, E 3 -) of said current flowing in the corresponding secondary conductor (42A, 44A, 46A, 42B, 44B, 46B,..., 42N, 44N, 46N), - the primary module comprises first means of compression of the measured value of the voltage (V1, V2, V3) and means of emitting, from the radioelectric emitter to the radioelectric receiver (80A,..., 80N) of the or of each secondary module (62A, 62B,..., 62N), a first message containing the compressed value of the voltage measured by the unit for measuring, - the measurement system comprises means (106, 120A,..., 120N, 122A,..., 122N) for the temporal synchronisation of the or of each intensity sensor (76A,..., 76N) in relation to the unit for measuring voltage, and - the calculating unit (126A,..., 126N) is connected to the radioelectric receiver (80A,..., 80N) and able to calculate the electrical power from the value of the measured voltage (V1, V2, V3) received from the primary module and from the value of the intensity (I1A,..., I3N) measured by the intensity sensor (76A,..., 76N), and