System for calculating an electric quantity, transformer sub-station comprising such a system and method for calculating an electric quantity with such a system

A method for calculating an electric quantity relative to an electrical installation, the electrical installation comprising a primary electrical conductor and several secondary electrical conductors electrically connected to the primary electrical conductor, the method being implemented using a calculating system including:

• a first module including a wireless transmitter,
• a plurality of second modules, each including a wireless transceiver and a current sensor capable of measuring the intensity of a current circulating in a corresponding conductor from among the primary and secondary electrical conductors,
• wherein the method comprises the following steps:
• a) the transmission, by the first module and to each second module, of a first time synchronization message of the measurement of the intensity of the current circulating in the primary or secondary conductors,
• b) reception of the first message by each second module,
• c) the quasi-simultaneous measurement, preferably with a synchronization margin of error smaller than 10 μs, of the intensity of the current circulating in the corresponding primary or secondary conductors by each current sensor,
• d) the transmission, by each second module and to a third module, of a second message containing at least one value of the intensity measured by the corresponding current sensor,
• e) the reception of the second messages by the third module,
• f) the calculation of the electric quantity from intensity values measured quasi-simultaneously and received via said second messages.