| 摘要 |
PURPOSE:To attain the complete cut-off of an overload current and to eliminate the useless power consumption by continuing a cut-off state in case the overload current flows again after cutting off immediately the overload current. CONSTITUTION:A load current ILa increases owing to some fault of a load resistance RL. Then the signal P1 is delivered to a cut-off control circuit 21 and a time limiting signal generating circuit 22 from a load detecting circuit 20 when the current ILa exceeds a prescribed level. Thus the circuit 21 closes a cut-off switch SQ to cut off an overload current. While the actuation of the circuit 22 which sets the closed period of the switch SQ is stopped by a cut-off state continuing circuit 23 in case the current ILa is detected again. Thus the closed state of the switch SQ is continued. This prevents the consumption of useless electric power and eliminates the generation of heat or the damage by burning of defective parts that affect other parts. |
