Fault rules when the compensation wire and the thermocouple graduation number do not match

charmfaith

Fault rules when the compensation wire and the thermocouple graduation number do not match [Copy link]

Figure 1 Schematic diagram of the thermoelectric potential of the circuit when the compensation wire and the thermocouple are mismatched The compensation wire and the thermocouple graduation number do not match yunrun.com.cn/tech/2053.html When the compensation wire and the thermocouple graduation number do not match, taking Figure 1 as an example, the total thermoelectric potential of the temperature measurement circuit is: EABCD (t, tn, t0) = eAB (t) + eBC (tn) + eCD (t0) + eDA (tn) It can be seen from the formula that the compensation wire and the thermocouple are mismatched. The total thermoelectric potential of the measuring circuit is not only affected by the temperature t, tn, and t0 of each junction, but also related to the type of compensation wire and thermocouple. Therefore, the display of the instrument may be too high or too low, which complicates the fault judgment. But there are still rules to follow. ① When tn＞t0, the thermoelectric potential value of the compensation wire per degree is greater than the thermoelectric potential value of the connected thermocouple per degree, and the temperature displayed by the instrument will be higher than the actual temperature; if the thermoelectric potential value of the compensation wire per degree is less than the thermoelectric potential value of the connected thermocouple per degree, the temperature displayed by the instrument will be lower than the actual temperature. ② When tn＜t0, the thermoelectric potential value of the compensation wire per degree is less than the thermoelectric potential value of the connected thermocouple per degree, and the temperature displayed by the instrument will be lower than the actual temperature; if the thermoelectric potential value of the compensation wire per degree is greater than the thermoelectric potential value of the connected thermocouple per degree, the temperature displayed by the instrument will be higher than the actual temperature.