As shown in table 4 is four measurements of the circuit, the cold end temperature change range: 0 ° C to + 70 ° C, hot end temperature kept at + 100 ° C. Table 4. Figure 4 circuit in different the cold end and heat end of the oven temperature measurement
Cold end temperature (° C) to measure the temperature of hot end * (° C)
Measured value # 1, 0.0 + 100.25
Measured value # 2 + 25.2 + 100.25
Measured value # 3 + 50.1 + 50.1
Measured value # 4 + 70.0 + 70.0
* hot side temperature is compensated values, were measured by the circuit.
conclusion
Due to the thermocouple temperature measuring device is difference, in dealing with a thermocouple signal must establish a reference point. Provided by the thermocouple voltage reflects the hot side and cold side temperature difference. If known to the cold end temperature and the relative to the cold end temperature of hot end, can identify the actual temperature on heat. Cold junction compensation device selection criteria and scope, cost, precision, linearity and temperature related, the highest platinum RTD precision, but the cost is the highest. Thermistor, low price, can work in relatively wide temperature range, but its poor linearity. Silicon temperature sensor detection IC working temperature range is narrow, but with reasonable accuracy and linearity, the cost is low, can meet the needs of most thermocouple used热电偶基本原理和使用方法常用热电偶分度号有S、B、K、E、T、J等，这些都是标准化热电偶。其中K型也即镍铬－镍硅热电偶，它是一种能测量较高温度的廉价热偶。由于这种 合金具有较好的高温抗氧化性，可适用于氧化性或中性介质中。它可长期测量1000度的高温，短期可测到1200度。它不能用于还原性介质中，否则，很快腐 蚀，在此情况下只能用于500度以下的测量。它比S型热偶要便宜很多，它的重复性很好，产生的热电势大，因而灵敏度很高，而且它的线性很好。虽然其测量精 度略低，但完全能满足工业测温要求，所以它是工业上最常用的热电偶。
概述：
作为工业测温中最广泛使用的温度传感器之一——热电偶，与铂热电阻一起，约占整个温度传感器总量的60%，热电偶通常和显示仪表等配套使用，直接测量各种生产过程中-40～1800℃范围内的液体、蒸气和气体介质以及固体的表面温度。 热电偶英文文献和中文翻译(6):http://www.youerw.com/fanyi/lunwen_9932.html