| 摘要 |
<p>1397414 Protective arrangements RUCKER CO 25 April 1972 [7 May 1971] 19198/72 Heading H2K An earth fault protective arrangement comprises a core-balance transformer 201 with its secondary winding 217 connected to an amplifier 202, an integrator 203, e.g. a capacitor 246, connected to the output of the amplifier and producing a trip signal having a magnitude corresponding to the magnitude and duration of the fault signal, and switching means, e.g. a silicon controlled rectifier 248, operated when the magnitude of the trip signal reaches a predetermined level. In the arrangement shown, when the capacitor 246 is sufficiently charged, a Zener diode 249 breaks down to trigger the SCR 248 into conduction. This causes sufficient current to flow in a circuit including a coil 259, bridge rectifier 261 ... 264 and the controlled rectifier 248, to cause the coil 259 to open contacts 258 in the protected circuit 211, 212. The bridge rectifier also supplies a pulse generator 208 which limits the voltage applied to the amplifier and provides a pulse current to a transformer 209 which couples the pulses to the conductors 211, 212 so that should the earthed neutral conductor 212 become earthed remotely, or the line conductor 211 become shorted to an unprotected conductor, the resulting pulse current would unbalance the core-balance transformer and cause operation of the protective arrangement. Reference has been directed by the Comptroller to Specification 1,353,411.</p> |
