| 摘要 |
<p>46,960 GROUND FAULT CIRCUIT INTERRUPTER WITH GROUNDED NEUTRAL PROTECTION A ground fault circuit interrupter includes a differential current transformer sensing winding supplying input to an integrator which is reset to zero at the end of each half-cycle of AC line current. A line-to-ground fault current will cause the integrator output to exceed a predetermined limit value and produce a trip indication. A saturable neutral transformer supplies a voltage to the neutral line and a reference current proportional to the neutral voltage to a comparator. The peak value of the reference current is compared to the peak value of the sensing winding output. A low resistance neutral-to-ground path causes the sensing winding output to exceed the reference current and a signal to be added to the integrator input, thereby producing a trip indication which energizes an SCR to activate a solenoid. Means are provided to produce a positive feedback signal to insure a "hard" turn-on of the SCR upon receipt of a trip indication, the feedback means also including capability to "remember" a trip indication at the end of a half-cycle near current zero, and to produce the positive feedback signal at the beginning of the next succeeding half cycle.</p> |
