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检定工业用热电偶时,要求把热电偶冷端置于0℃的冷端恒温器中。由于条件限制,检定时热电偶冷端往往无法实现0℃,而是裸露于空气中或置于一定温度(如25℃)的油中。《0—1300℃工业用热电偶检定规程》规定:在检定热电偶时,必须把热电偶冷端置于0℃的冷端恒温器内。不然,则各连接点温度必须保持稳定,并用水银温度计测出冷端温度,然后用下式进行修正: E(t,t_o)=E(t,t′)+E(t′,t_o)式中,E—热电偶热电势值,t—热电偶工作端温度,t_o—冷端规定温度,即0℃;t—冷端的实际温度。但是,从热电偶分度表可以看出,热电偶
When testing industrial thermocouples, it is required that the cold junction of the thermocouple be placed in a cold junction thermostat at 0 ° C. Due to limited conditions, the thermocouple cold end of the test often can not achieve 0 ℃, but exposed to the air or placed in a certain temperature (such as 25 ℃) oil. “0-1300 ℃ industrial thermocouple test procedures” provides: When testing the thermocouple, thermocouple cold junction must be placed at 0 ℃ cold-side thermostat. Otherwise, the junction temperature must be kept constant and the cold junction temperature measured with a mercury thermometer and then corrected using the following equation: E (t, t_o) = E (t, t ’) + E (t’, t_o) , E-thermocouple thermoelectric potential value, t-thermocouple working end temperature, t_o- cold end specified temperature, that is 0 ° C; t- cold end of the actual temperature. However, thermocouples can be seen from the thermocouple index table