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熱電対構造熱電対01Thermocouple熱電対1．熱電対素線用語の意味熱電対の両脚となる金属線及び合金線Thermocouple 2.絶縁碍子熱電対の素線相互間の短絡を防ぐための管3.保護管測温接点や素線が、被測温物又は雰囲気などに直接接触しないように保護するために付ける管4.測温接点熱電対の素線を接合した接点で、温度を測る位置に置かれるもの5.補償導線TA When two dissimilar metal conductors are connected together to form a closed circuit and the two junctions are kept in different temperatures, thermal electromotive force(EMF) is generated in the circuit. Thus, when one end (cold junction) is kept constant at a certain temperature, normally at 0℃, and the other end (measuring junction) is exposed to unknown temperature, the temperature at latter end can be determined by measurement of EMF so generated. This combination of two dissimilar metal conductors are called "thermocouple".The direction and magnitude of the EMF generated depend upon the temperature of the two junctions and upon the materials making up the thermocouple, and not affected by the size or length of the thermocouple wire.StructureDefinitions1．Thermocouple Wires A thermocouple assembly consists of thermocouple element, protection tube, terminal head, insulators and mounting bracket.Metallic wire and alloy wire to be used for both legs of thermocouple.2．InsulatorsInsulators are used to prevent from mutual short circuit of thermocouple wires3．Protection TubeA protection tube is used to protect the temperature measuring junction and element wires from touching directly to the object under measurement of temperature or environment.4．Hot junction Hot junction formed by the thermocouple wires, shall be set on the position to be measured the temperature.5．Compensating CableA couple of insulated conductors having approximately the same thermoelectric characteristics with the thermocouple to be used jointly, within adequate temperature range including normal temperature, and shall be used for compensation of error produced by the temperature variation at the terminal part of thermocouple by connecting it between the terminal of thermocouple and reference junction. 二種類の異なった金属導体の両端を電気的に接続し、この両端に温度差を与えると、この閉回路に熱起電力が発生し、回路中に電流が流れます。　一端（基準接点）の温度を一定温度（原則として０℃）に保ち、熱起電力の値を測定することで、他端（測温接点）の温度を知ることができます。 この二種類の金属導体を”熱電対”といいます。 熱起電力の大きさとその極性は、両端の温度と二種類の金属導体の組み合わせによって決まり、太さや長さには影響されません。 常温を含む相当な温度範囲において、組み合わせて使用する熱電対とほぼ同一の熱電的特性をもつ一対の導体に絶縁を施したものをいい、熱電対の端子と基準接点との間をこれにより接続し、熱電対の端子部分の温度変化によって生じる誤差を補償するために使用する 熱電対は実用上、熱電対素線、保護管、端子箱、絶縁碍子その他必要な取付金具などから構成されます。

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