一种热电偶时间常数测试系统

A thermocouple time constant test system

时间常数是检测热电偶动态测试性能的重要指标.为了衡量热电偶的动态测试性能,设计了一种热电偶时间常数测试系统,包括热电偶、恒温槽、数据采集卡、激光对射式光电传感器.测试过程中,由激光对射式光电传感器记录热电偶接触恒温槽恒温介质时间点,由数据采集卡采集热电偶的温度数据以及激光对射式光电传感器的电压数据,由数据采集软件显示并记录温度与电压变化曲线.对热电偶的温度数据进行了拟合,测得热电偶的时间常数并与理论计算值进行了比较.最后对测试过程产生的误差进行了分析.分析结果表明,该热电偶时间常数测试系统可大幅度减少热电偶自身的热惰性所引起的测量误差,但仍会产生其它微小测量误差.

Time constant is an important indicator used to test the dynamic performance of a thermocouple. In order to measure the dynamic performance of a thermocouple, we designed a thermocouple time constant test system. The system is composed of a thermoeouple, a thermostatic bath, a data acquisition card and an opposite type laser photoelectric sensor. In the test process, when the thermocouple contacted the thermostatic bath thermostatic medium to capture the moment by the opposite type laser photoelectric sensor, the temperature data of the thermocouple and the voltage data of the opposite type laser photoelectric sensor were collected by the data acquisition card. The temperature and voltage change curves were displayed and recorded by the data acquisition software. The temperature data of the thermocouple were fitted. The time constant of the thermocouple was tested and the calculated values were compared with the theoretical calculation. Finally, the error of the tested process was analyzed. The results show that the thermoeouple time constant test system can greatly reduce the measurement error caused by thermal inertia of thermoeouple itself with other micro measurement errors.