| 摘要 |
<p>PURPOSE:To obtain a reliable transformer by protecting the instrument transformer with a nonlinear impedance circuit including thyristors connected to a reactor in parallel in the occurrence of secondary short circuit. CONSTITUTION:A principal capacitor 1 and a voltage dividing capacitor 2 are connected in series between a line and the ground, a transformer 3 is connected to the voltage dividing capacitor 2 in parallel, a reactor 4 is connected to the secondary circuit 7 of the transformer 3 in series, and a nonlinear impedance circuit 17 is connected to the reactor 4 in parallel. In this wiring, when a short circuit occurs on the secondary side of the transformer 3, an excessive current flows thereto, and the terminal voltage of the reactor 4 rises up to a certain value, the voltage of diodes 13 constructing the circuit 17 exceeds the Zener voltage of Zener diodes 14 and a current flows through the gates of thyristors 15 to short-circuit both the ends of the reactor 4. If the terminal voltage of the reactor 4, at which the thyristors 15 is converted into a conductive state, is determined with the Zener voltage of the diodes 14 and the resistance of resistors 16, the terminal voltage of the voltage dividing capacitor 2 is set to a fixed value or less to prevent the voltage from increasing.</p> |
