| 摘要 |
PURPOSE:To enable reducing a shape of an input transformer in a digital protec tion relay. CONSTITUTION:A circuit comprises at least first, second and third resistors 1, 4, 5 and first and second capacitors 2, 6, an insulating transformer 3 and an arithmetic amplifier 7, connecting in series the first resistor 1 and the first capacitor 2 and also connecting in parallel the first capacitor 2 and the insulating transformer 3. The second resistor 4 is connected between the one end of secondary side of this insulating transformer and an inversion input terminal of the arithmetic amplifier 7, the second capacitor 6 between the inversion input terminal and output terminal of the arithmetic amplifier 7 and the third resistor 5 between the one end of the insulating transformer 3 and output terminal of the arithmetic amplifier 7. Moreover, the other end of the secondary side of the insulating transformer 3 is connected to an normal input terminal of the arithmetic amplifier 7 direct or via a compensating circuit. |
