Overcurrent and distance protection for low, medium and high voltage electric line circuits, uses semiconductor switch controlled by overcurrent and distance sensing circuits

摘要

Electric line (5) protection system (1) having two fault sensors (4a,4b). The first (4a) is in active connection to a semiconductor switch (6) fitted in the line (5), which sends, when a first trigger condition is fulfilled, a disconnection signal (7a) to the switch (6), which causes it to open the line circuit. The second sensor (4b) interrupts the disconnection operation when a second triggers condition is not satisfied. The two sensors (4a,4b) and the semi-conductor switch are designed to operate in low, medium and high voltage circuits. The sensor (4b) includes a part for detecting and maintaining a current (i) at a voltage (u), a computing unit, a comparison unit and elapsed time control. The switch (6) has a varistor in parallel with it. The first sensor provides overcurrent protection and the second (4b) distance protection. An Independent Claim is also included for: a protection method.