| 摘要 |
<p>PURPOSE:To detect an AC including a DC component highly accurately, by integrating the voltage induced in a current detecting current transformer, detecting magnetic deflection, and generating the electromotive force in the reverse direction in the current transformer. CONSTITUTION:The current, which is proportional to a primary current I1 flowing in a main circuit 10, is flowed in the secondary side of the current transformer 52. The voltage induced in the current transformer 52 is integrated by an integrating circuit formed by a resistor 22 of a magnetic deflection preventing part 18 in a current detecting circuit 16, a capacitor 24, and an operation amplifier 26. The integrated value is applied to operation amplifiers 36 and 38. When the magnetic deflection of the current transformer 52 becomes a specified value or more in the positive or negative direction, a transistor 28 or 30 is turned OFF through the amplifier 36 or 38. A Zener voltage caused by a Zener diode 32 or 34 is fed back to the secondary side of the current transformer 52, and the magnetic deflection is prevented. Thus, the AC including the DC component is highly accurately detected by an output synthesizing part without affecting the magnetic deflection.</p> |
