| 摘要 |
PURPOSE:To decrease the number of cores, to simplify an installation work, and also to realize a measurement in a short time and a stable measurement, by connecting three terminals of a potentiometer type variable resistance set in a remote place, to three terminals of a measurement side through a three-core cable, and providing a resistor, a voltage generating circuit and an arithmetic circuit among said three terminals. CONSTITUTION:A voltage V1 from a voltage generating circuit 4 is applied to the terminal 2a of a core wire 2-1 of a three-cover cable, and the other terminal of a resistor 3. A voltage obtained through a core-wire 2-2 from the movable piece side of a variable resistor 1, and a voltage generated in the terminal 2c of the resistor 3 are denoted as V2 and V3, respectively, and for instance, the movable piece of the resistor 1 is in a position having the resistance value of aR0 (0<=a<=1) from a terminal 1a. An arithmetic circuit 5 receives the voltages V1-V3, and calculates V4=V1-2V2+ V3=(2a-1)R0. The output V4 of the circuit 5 is inputted to an A/D converter 6, and by receiving the voltage V3, V4/V3=2a-1 is outputted from the A/D converter 6, and displayed on a displaying circuit 7. In this way, a resistance ratio determined by a position of the variable resistor 1 is measured.
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