| 摘要 |
<p>A GFCI utilizes a single transformer in responding to ground faults on either of the line and neutral conductors of a distribution circuit. The transformer, a differential current transformer, has a secondary winding which is periodically strobed during a first sampling interval for the presence of a fault signal indicative of a line-ground fault. During a second sampling interval, a negative resistance network sets up a ringing oscillation in the transformer secondary circuit. If the neutral conductor is grounded through a low impedance ground fault, the oscillation is damped, and circuit interruption is initated. Absent a low impedance ground fault on the neutral conductor, the oscillation amplitude increases to exceed a predetermined threshold level during the second sampling interval, and circuit interruption is not initiated.</p> |
