Principle of Sensors传感器原理热电式传感器Thermoelectric Sensors 7.2.2 热电偶的工作定律Working Law of Thermocouple 中间导体定律中间导体定律中间导体定律中间导体定律The Law of Intermediate Conductors The Law of Intermediate Conductors 如图，在T0处接入第3种导体C，若A、B节点处温度为T，其余节点温度为T0，且TT0，则三种材料组成的闭合回路总热电势为：As shown in the figure,the third conductor C is connected at T0.If the temperature at nodes A and B is T,and the temperature at other nodes is T0,and T T0,the total thermoelectric potential of the closed loop composed of the three materials is:根据上述原理，可以在热电偶回路中接入电位计E，只要保证电位计与连接热电偶处的接点温度相等，就不会影响回路中原来的热电势，接入的方式见下图所示。
According to the above principle,the potentiometer E can be connected to the thermocouple circuit.As long as the temperature of the potentiometer and the contact where the thermocouple is connected is equal,the original thermoelectric potential in the circuit will not be affected.The connection mode is shown in the following figure.中间导体定律：当热电偶引入第三导体中间导体定律：当热电偶引入第三导体中间导体定律：当热电偶引入第三导体中间导体定律：当热电偶引入第三导体C C 时，只要时，只要时，只要时，只要C C导体两端温度相同，回路总电势不变导体两端温度相同，回路总电势不变导体两端温度相同，回路总电势不变导体两端温度相同，回路总电势不变Law of intermediate conductor:When the thermocouple is introduced into the third conductor C,as Law of intermediate conductor:When the thermocouple is introduced into the third conductor C,as long as the temperature at both ends of the conductor C is the same,the total potential of the loop long as the temperature at both ends of the conductor C is the same,the total potential of the loop remains unchanged.remains unchanged.电位计接入电位计接入电位计接入电位计接入 热电偶回路热电偶回路热电偶回路热电偶回路Potentiometer connected to Potentiometer connected to thermocouple circuit thermocouple circuit 中间温度定律中间温度定律中间温度定律中间温度定律 ：如果不同的两种导体材料组成热电偶回路,其接点温度分别为T1、T2(如图所示)时,则其热电势为EAB(T1,T2)；当接点温度为T2、T3时，其热电势为EAB(T2,T3)；当接点温度为T1、T3时，其热电势为EAB(T1,T3)，则Law of intermediate temperature:Law of intermediate temperature:If the thermocouple circuit is composed of two different conductor materials and its contact temperature is T1 and T2 respectively(as shown in the figure),its thermoelectric potential is EAB(T1,T2);When the contact temperature is T2 and T3,the thermoelectric potential is EAB(T2,T3).When the contact temperature is T1,T3,and the thermoelectric potential is EAB(T1,T3),then 讨论：讨论：讨论：讨论：当在原来热电偶回路中分别引入与导体材料A、B同样热电特性的材料A、B(如图)即引入所谓补偿导线时，则回路总电动势为(Discussion:Discussion:When the materials A B with the same thermoelectric properties as the conductor materials A B(as shown in the figure)are respectively introduced into the original thermocouple circuit,i.e.the so-called compensation wire is introduced,the total electromotive force of the circuit is)只要T1、T0不变，接入AB后不管接点温度T2如何变化，都不影响总热电势。
这便是工业上运用补偿导线进行温度测量的原理As long as T1 and T0 remain unchanged,the total thermoelectric potential will not be affected no matter how the contact temperature T2 changes after being connected to AB.This is the principle of temperature measurement using compensation wire in industry.）中间温度定律为热电偶分度表分度表分度表分度表的制定提供了依据如当T3=0时，则可求出参考温度不为零时的温度值(The law of intermediate temperature provides a basis for the formulation of thermocouple indexing table.If T3=0,the temperature value when the reference temperature is not zero can be obtained)diagram of thermocouple compensation wire参考电极定律参考电极定律参考电极定律参考电极定律 Reference electrode law Reference electrode law 如果任意两种导体材料的热电势是已知的，它们的冷端和热端的温度又分别相等，如图所示，它们相互间热电势的关系为:If the thermoelectric potentials of any two conductor materials are known,and the temperatures of their cold and hot ends are equal respectively,as shown in the figure,the relationship between their thermoelectric potentials is as follows:。