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热电偶输出的热电势只有在参比端温度t_0.恒定或已知时,才能反映测量端的温度t,但是,热电偶参比端所处的环境温度总有波动,使测量得不到正确的结果.因此,用热电偶测温时必须对其参比端温度进行处理.参比端温度补偿器是一种对热电偶参比端温度变化自动进行修正的装置.常用的参比端温度补偿器为一不平衡电桥,如图1示.我国统一设计生产的补偿器电源电压E=4V,桥臂电阻R_1=R_2=R_3=1Ω,R_cu为随温度变化的铜热电阻,在参比端温度为t_0.时,R_Cu=1Ω,电桥处于平衡状态,其输出电压V_d=0,热电偶输出热电势为E_AB(t,t_0).当热电偶参比端温度升高到t_0时,热电偶输出热电势为E_AB(t,t_0)-E_AB(t_0,t_0),这时,补偿器输出电压V_cd=E_AB(t_0,t_0),使测量回路中总电势维持E_AB(t,t_0)不变,从而实现对参比端温度变化的实时自动修正.
Thermocouple thermocouple output only in the reference junction temperature t_0. Constant or known to reflect the temperature measuring terminal t, However, the thermocouple reference junction where the ambient temperature there is always fluctuating, the measurement is not correct The thermocouple temperature measurement, therefore, the reference junction temperature must be processed.Reference junction temperature compensator is a thermocouple reference junction temperature changes automatically corrected device commonly used reference junction temperature compensation As an unbalanced bridge, shown in Figure 1. China’s unified design and production of compensator supply voltage E = 4V, arm resistance R_1 = R_2 = R_3 = 1Ω, R_cu copper temperature resistance with temperature changes in the reference When the temperature of the terminal is t_0, R_Cu = 1Ω, the bridge is in equilibrium, the output voltage V_d = 0, the thermocouple output thermoelectric power is E_AB (t, t_0) .When the thermocouple reference junction temperature rises to t_0, Thermocouple output thermoelectric power E_AB (t, t_0) -E_AB (t_0, t_0), then compensator output voltage V_cd = E_AB (t_0, t_0), the total potential in the measurement circuit to maintain E_AB (t, t_0) Change, in order to achieve real-time automatic correction of temperature changes at the reference junction.