Fault locator in an electrical power transmission system

A fault locator for an electrical power transmission system comprises a power system signal sensor unit 1 comprising a module 5 for sensing the currents in each phase, a module 7 for sensing the voltages of each phase, and a protection module 9 linked to the power system breakers 10. The current, voltage and status signals of the breakers are transmitted to a first microprocessor 18 with memories 19 and means for detecting the existence of a fault by comparing the measured values in each cycle of received signals. A corresponding fault signal is sent to a second microprocessor 22 with memories 24 and means for calculating, by means of an iterative process and a fault-locating algorithm, the distance at which the fault is located and its resistance.