The structure and working principle of thermocouple - Shanghai dragon instrument electric appliance co. , LTD

A, what is a thermocouple thermocouple is industry one of the most commonly used temperature detecting element, the thermocouple operating principle is based on baker ( seeback) Effect, that is, two different ingredients of conductor connection into a loop, such as two different cohesive end temperature, the thermal current physical occur within the loop. Second, the basic principle of thermocouple temperature measuring thermocouple is a temperature sensing element, is an appearance, it direct measurement of temperature, and the temperature signals into a thermoelectric emfs, repass electric appearance ( Secondary appearance) Convert the temperature of the measured medium. Thermocouple temperature measurement is the basic principle of two kinds of different ingredients of closed loop conductor material composition, when there is a temperature gradient when two loop will have current through the, two head existed between the electromotive force at the moment - — Thermoelectric emf, this is the so-called seebeck effect. Two different components of homogeneous conductor electrode as heat, the temperature is higher at one end of the end for homework, temperature low end to end, free end under a constant temperature. According to the thermoelectric emfs associated with 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. Access the third metal materials in the thermocouple loop when only two contacts at the same temperature, the data of thermocouple thermoelectric is set to remain the same, which is not affected by the third metal access in the loop. Therefore, when the thermocouple temperature measurement, can access measurement appearance, measured after the thermoelectric emfs, can know the temperature of the measured medium. When the conductor A and B two persistent point temperature difference between 1 and 2, occurs between the electromotive force, thus forming A range of current in the circuit, this kind of phenomenon called the thermoelectric effect. Thermocouple is using this effect to homework. Two kinds of different ingredients of conductor ( Called the thermocouple wire or hot electrode) Juncture of synthesis loop at both ends, when the temperature is not at the same time, the electromotive force occurs in the loop, this kind of phenomenon called the thermoelectric effect, and the electromotive force called thermoelectric potential. Thermocouple is using the principle of temperature measurement, meanwhile, directly used as a measurement of the medium temperature is called the homework at the end of the end ( Also known as the measurement end) , on the other side called cold end ( Also known as compensation) ； The cold end and appearance looks or supporting they cohesion, show appearance will point out the thermocouple thermoelectric potential of what had happened. Thermocouple is actually a kind of energy converter, it converts heat energy to electricity, with the thermoelectric potential measurement of temperature, the thermocouple thermoelectric potential, we should pay attention to the following questions: 1: thermocouple thermoelectric potential is thermocouple temperature function is poor, both ends instead of thermocouple temperature difference both ends functions; 2: what happens to thermocouple thermoelectric potential of intrusive, when thermocouple information is uniform, has nothing to do with the length and diameter of thermocouple, only with thermocouple data elements related to the temperature difference between the two; 3: when the thermocouple two thermocouple wire material composition is determined, the thermocouple thermoelectric potential intrusive, only related with the thermocouple temperature difference; If the thermocouple cold end temperature keeping, this into the thermocouple thermoelectric potential is only part of the job end temperature of single value function.