| 摘要 |
PURPOSE:To reduce the number of thermometers and compensating lead wires used for break connection, by making the constitution of strands different in each of hot junctions of a thermocouple which are connected in series. CONSTITUTION:When strands of a thermocouple are connected in series, thermo- electromotive forces of hot junctions 3-6 for temperature are different from one another because of the constitution of strands. This difference of thermo-electromotive force is utilized to detect a break. Since hot junctions 8, 9, 10, and 11 of the thermocouple are used only to detect the temperature difference among hot junctions, cold junctions are unnecessary, and it is unnecessary to use compensating lead wires as conductors 7 which lead thermo-electromotive force to a thermo-electromotive force discriminating circuit 12. When a break occurs in an instrumentation piping, the temperature of this instrumentation piping is saturated to a certain temperature (tx), and therefore, thermo-electromotive force for saturation is discriminated by the thermo-electromotive force discriminating circuit 12 to discriminate this instrumentation piping. |
