AUTOMATIC LOOP CIRCUIT FOR CABLE FAULT TEST

摘要

PURPOSE: An auto-loop circuit for contrasting/testing an insulated conductor of a subscriber line is provided to easily test the insulated conductor in a telephone office at contrasting/testing the insulator conductor by forming a loop for testing the insulator conductor using the only testing power in a testing room in the telephone office. CONSTITUTION: A reverse current preventing part(310) allows a current to flow in same direction. A continuous current limiting part(320) blocks the current flow after passing a voltage from the reverse current preventing part(310). The first voltage detecting part(330) detects and outputs the voltage applied through the continuous current limiting part(320). The first switching part(340) switches the voltage applied from the reverse current preventing part(310). A delay part(350) delays the voltage from the first switching part(340). The second voltage detecting part(360) detects the voltage applied through the delay part(350). The third voltage detecting part(370) detects and outputs the voltage applied through the first switching part(340). The second switching part(380) switches the voltage from the reverse current preventing part(310) and passes it to two insulated conductor(L1,L2), by the voltage applied from the second voltage detecting part(360). The third switching part(390) switches the voltage from the reverse current preventing part(310) and passes it to two insulated conductor(L1,L2), by the voltage applied from the third voltage detecting part(370).