| 摘要 |
<p>4/dr 58414-4 A differential protection circuit is responsive to measured current pulses generated upon the occurrence of external and internal faults within a protected device for emitting blocking and tripping signals respectively upon the occurrence of an external and an internal fault of the protective device: The measured current pulses are rectified and level-sensing means in a stabilizing circuit is responsive to the rectified current pulses. A stabilizing potentiometer is connected in series with the level-sensing means and a differential circuit is connected to the sliding terminal of the potentiometer. Both the stabilizing circuit and the differential circuit include gating means such that the emission of tripping signals is blocked upon the emission of output signals of the gating devices in the stabilizing circuit; and tripping signals are emitted upon the emission of output signals from the gating devices in the differential circuit. The differential protection circuitry may include fast-acting mechanical relays or electric logic circuitry.</p> |
