Analysis of Three Major Causes of Industrial Thermocouple Measurement Error
Industrial thermocouples may produce errors during temperature measurement. The main reasons for errors are the following three aspects:
It is necessary to maintain a certain time during temperature measurement to achieve thermal equilibrium between the two. The length of the holding time is related to the thermal response time of the temperature measuring element. The thermocouple thermal response time depends on the structure of the sensor and the measurement conditions. 以上才能达到平衡;对于液体而言，最快也要在5min以上。 For gaseous media, especially stationary gas, it should be maintained for at least 30 minutes to reach equilibrium ; for liquids, the fastest should be more than 5 minutes .
2. Insertion depth
When an industrial thermocouple is inserted into the measurement site, a heat flow is generated along the length of the sensor. There is heat loss when the ambient temperature is low. As a result, the temperature of the thermocouple and the measured object are inconsistent, resulting in a temperature measurement error.
3. Heat radiation
The thermocouple inserted into the furnace for temperature measurement will be heated by the heat radiation from the hot object. It is assumed that the gas in the furnace is transparent, and when the temperature difference between the thermocouple and the furnace wall is large, a temperature measurement error will occur due to energy exchange. To reduce the heat radiation error, increase the heat conduction and make the furnace wall temperature as close as possible to the temperature of the thermocouple.