The correction method for thermocouple is _ instrument

As a result of the thermocouple temperature a thermoelectric potential curve ( Thermocouple indexing table) Is in the cold end temperature to keep O ℃, under the condition of instrument to be used together with it is according to the curve calibration, so although USES compensation conductor should be make temperature with thermocouple cold end extends to the place, but as long as not for O ℃ cold end temperature, indicating value of the instrument must be treated in correction. If the hot end of the temperature measuring thermocouple temperature T, the cold end temperature of Tn rather than 0 ℃, the output voltage of the thermocouple have been measured for E ( T, Tn) , according to the law of middle temperature (E T O℃) =E( T, Tn) +E( Tn, O℃) To calculate the hot end temperature T, the cold end to the thermoelectric potential when O ℃, and then from the hot end of indexing table check temperature T. It should be noted that due to the thermocouple temperature nonlinear electric potential curve, addition of what is said above is the addition of a thermoelectric potential, rather than the temperature of the simple addition. For example: with nickel chromium nickel silicon thermocouple temperature measurement, temperature of the cold junction of the thermocouple Tn = 30 ℃, measured the cold end is 30 ℃ when the thermoelectric potential of E ( T, Tn) = 40. 347 mV, by dividing table look up to 30 ℃ hot end and cold end 0 ℃ when the thermoelectric potential (E Tn,0℃) = 1. 203 mV, E ( T，O) = E ( T, Tn) + E ( T O) = ( 40. 347 + 1. 203). mV = 41。 55 the mv, also by indexing table Chad T = 1010 ℃. Thermocouple temperature measurement is the basic principle of two kinds of different ingredients of closed loop conductor material composition, when when there is a temperature gradient at both ends, loop will have an electric current passes through, the existed between the electromotive force on both ends - Thermoelectric emf, this is the so-called seebeck effect ( 塞贝克效应) 。 Two different components of homogeneous conductor electrode as heat, the temperature is higher for work at the end of the end, one end of the low temperature as the free end, usually free end under a constant temperature. According to the thermoelectric emf as a function of temperature, the thermocouple indexing table; Indexing table is free end temperature at 0 ℃, under the condition of different thermocouples with different indexing table. Thermocouple thermoelectric properties is decided by two aspects of the thermocouple thermoelectric properties, it is to point to in a certain temperature, the two kinds of the metal contact surface, produce the phenomenon of electric potential difference. 1. The size of the thermocouple loop properties related to material properties and temperature on both ends, only has nothing to do with the length of the thermocouple, coarse fine. 2. There are only two different nature of the conductor to form a thermocouple. When the temperature of the thermocouple at both ends is not at the same time, will produce thermoelectric potential. 3. And the size of the thermoelectric potential only after the material is related to the thermocouple temperature on both ends. Thermocouple is based on thermoelectric effect measuring temperature sensor, is commonly used in temperature measuring instrument of temperature measuring element. The appearance of all kinds of thermocouple is often due to the need to vary, but their basic structure is roughly same, usually by the hot electrode, insulation sleeve to protect the main parts such as pipe and connection box, by compensating conductor and digital display table, recording instrument and electronic regulator.