The working principle of thermocouple temperature sensor

the basic principle of thermocouple temperature measurement are two different components of the material of conductor closed loop, when temperature gradient is at both ends, the 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. 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.

in the thermocouple circuit connected to the third kind of metal material, the two contacts at the same temperature as long as the material, produced by the 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 be connected to the measuring instrument, measured after the thermoelectric emfs, can know the temperature of the measured medium.

the working principle of thermocouple temperature sensor

two different ingredients of conductor ( Called the thermocouple wire or hot electrode) Two ends synthesis loop, when the junction temperature is not at the same time, in the circuit will generate electromotive force, this kind of phenomenon called the thermoelectric effect, and the electromotive force called thermoelectric potential. Thermocouple is to use the principle of temperature measurement, which directly used for measuring the medium temperature is called at the end of the working side ( Also known as the measuring end) , on the other side called cold end ( Also known as compensation) ； The cold end connected to the display instrument or meter, display instrument will point out the thermocouple thermoelectric potential.

thermocouple is actually a kind of energy converter, it converts heat into electricity, using thermoelectric potential generated by the measuring temperature, the thermocouple thermoelectric potential, several problems should be paid attention to the following:

1: thermocouple thermoelectric potential is thermocouple temperature on both ends of the work on the function of the poor, rather than the thermocouple cold end with the job, temperature difference on both ends of the function;

2: the size of the thermocouple thermoelectric potential produced by, when material is uniform thermocouple, has nothing to do with the length and diameter of thermocouple, and only at the ends of the thermocouple material composition and temperature difference;

3: when the two thermocouple wire thermocouple material component is determined, the size of the thermocouple thermoelectric potential, only related with the thermocouple temperature difference; If the thermocouple cold end temperature keeping, this into the thermocouple thermoelectric potential is only the end of the single value function of temperature. Two different welding material A conductor or semi-conductor A and B, form A closed loop, as shown. When the conductor A and B two persistent point temperature difference between 1 and 2, produces an electromotive force between two people, thus forming the size of A current in the circuit, this kind of phenomenon called the thermoelectric effect. Thermocouple is in using this effect to work.

temperature is on the sample average kinetic energy of particles in the way of measuring object, is the standard unit 'degree'. Temperature can be achieved by different methods to measure, measure the cost and also each are not identical. The thermocouple is one kind of common measuring temperature sensor, because of the thermocouple is relatively cheap and degree is high, and its measuring range is relatively wide.

when two different metals contact, party to produce a contact point with the function of the temperature low no-load voltage, this is called the thermoelectric effect. The thermoelectric voltage is the Seebeck voltage in 1821 found that the phenomenon of physicists ThomasSeebeck naming. The voltage relative to temperature is nonlinear, but for a small scale changes in temperature can be considered linear approximation, or:

( 1)

type in? V is the voltage change, S is the Seebeck coefficient, and? T is the temperature change.

there are many types of thermocouple, and according to the American national standards institute ( ANSI） Convention, the larger letters indicate its composition. J type thermocouple, for example, by a metal conductor and a copper nickel alloy conductors. Other types include thermocouple B, E, K, N, R, S, and T.

PT100 armoured platinum thermal resistance and armored thermal resistance difference between

PT100 armoured platinum thermal resistance is to use the material when the temperature changes, its resistance also along with the change of characteristics to measure temperature. When resistance changes, the work shows the temperature resistance of the meter. Armoured PT100 armoured platinum resistance thermal resistor is a kind of temperature sensor, it is smaller than the diameter of a prefabricated thermal resistance, flexible, good vibration resistance, suitable for installation in the case of prefabricated thermal resistance can't install, WZPK armoured platinum resistance series adopts imported thermal resistance temperature measurement component, therefore, has a fast, sensitive and thermal response time, stable quality, long service life, etc.

PT100 armoured platinum thermal resistance protective mining have stainless steel, full of high-density oxide material inside insulation, therefore, armored thermal resistance strong pollution resistance and mechanical strength, suitable for installation in harsh environment.

PT100 armoured platinum thermal resistance usually by armoured platinum thermal resistance temperature sensing element, install fixtures and wiring devices and other major parts, such as thermal response time, reduce the dynamic error; Small diameter, length is not restricted; High measuring accuracy; Imported film resistance element, performance stable and reliable; The normal temperature insulation resistance; Thermal resistance at ambient temperature for 15 - 35 ° c, relative humidity is not more than 80%, the test voltage for 10 - 100v( Dc) Electrode and the outer casing of the insulation resistance between > 100 m Ω.

armored thermal resistance, although is also widely applied in industry, but because of its temperature range makes his application by certain restrictions, thermal resistance temperature measurement principle is based on a conductor or semiconductor resistance changes with the change in temperature. Its many advantages, can also remote transmission signal, high sensitivity, strong stability, compatibility and accuracy are better, but you need to power, can't instantaneous measured the change in temperature. Industrial heat resistance generally adopts Pt100, Pt10 Cu50, Cu100, platinum thermal resistance temperature measurement range is generally 200 - below zero 800 ℃, the thermal resistance of copper of 40 to 140 ℃ below zero. Thermal resistance and thermocouple as the distinction between the type, but it does not need compensation conductor, and is much cheaper than thermocouple.