| 摘要 |
<p>PURPOSE:To perform good-linearity noncontact type current detection with high accuracy by measuring a detection coil current at the balanced point between the magnetic field produced by the current to be measured of an electrical wire and another magnetic field for compensating the first-mentioned magnetic field produced by the current of the detection coil. CONSTITUTION:This noncontact type current detecting device is constituted in such a way that a detection coil 2, both ends of which are connected with a control circuit 4 through conductors 5 and 6, is provided near an electrical wire 1 of a straight linear conductor having an infinite length and a magnetic field detecting element 3, the detecting signal of which is connected with the control circuit 4 through a conductor 7, is provided at the center P of the coil 2. The circuit 4 makes an electric current (i) which produces a magnetic field H2 for compensating the magnetic field H1 produced by an electric current to be measured at the position of the element 3 at the same position to flow to the coil 2. The element 3 reacts the resultant magnetic field of both magnetic fields and outputs a voltage signal which changes proportionally to the resultant magnetic field. The circuit 4 controls the current (i) so that the input voltage (=resultant magnetic field) can be approximated to zero. Since the current to be measured when the input voltage becomes zero can be found from the current (i), the voltage corresponding to the current (i) is outputted to a measuring instrument 9 through a resistor 4i connected in series with the coil 2.</p> |
