| 摘要 |
The output from a solid state sensing device associated with an electrical supply line is fed to a differential amplifier (8). The output from the amplifier (8) is fed to an auto compensating amplifier (10), the time-constant of which is determined by a capacitor (11) and a resistor (12). This time-constant is made long with respect to the sinusoidal supply frequency generating the measured current. By this means all D.C. components at the output of the amplifier (8) will be removed so that slow changes due to temperature and age of components in the solid state device (1) and the amplifier (8) will not affect the output from the amplifier (8). |
