The difference between two kinds of thermocouple and thermocouple temperature instrument is what _ instrument2

Thermocouple is one of the industry commonly used temperature detecting element, the working principle of the thermocouple is based on baker ( seeback) Effect, that is, two different components of conductor ends connected into a circuit, such as two different connection end temperature, then to produce the physical phenomenon of thermal current in the circuit. Advantage is wide measuring range. The commonly used thermocouple from - 50 ~ + 1600 ℃ can renew edge measurement, some special thermocouple low measurable to - 269℃( Such as gold iron nickel chrome) Up to + 2800 ℃ ( Such as tungsten - Rhenium) 。 Simple structure, easy to use. Thermocouple is usually composed of two different kinds of metal wire, but is not limited by the size and the beginning of, outside has protective casing, which are very convenient. 1. Basic principle of thermocouple temperature measurement will be two different welding material a conductor or semi-conductor a and b to form a closed loop, when the conductor a and b two persistent point temperature difference between 1 and 2, occurs between the electromotive force, and thus form the size of a current in the circuit, this kind of phenomenon called the thermoelectric effect. Thermocouple is in using this effect to work. Commonly used in low temperature zone thermocouple thermocouple is a kind of temperature detector. Its main characteristic is high accuracy, stable performance. The platinum thermocouple measurement accuracy is very high, it is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. 1, thermocouple temperature measurement principle and material of thermocouple temperature measurement is based on the metal conductor resistance value increases with the increase of the temperature of the properties for temperature measurement. Thermocouples are mostly made of pure metal materials, the current application of platinum and copper, in addition, now began to use the materials such as nickel, manganese and rhodium thermocouple. 2, the type of thermocouple type thermocouple from thermocouple temperature measurement principle, the measured the change in temperature is directly measured by thermocouple resistance change, therefore, the wires of a thermocouple body such as a variety of wire resistance change will affect temperature measurement. Thermocouple thermocouple is by thermal components ( The resistor body) , wire, insulation materials, stainless steel casing combination solid body, its diameter is commonly phi - 2 Phi is 8 mm, achieve more xiaoke phi is 0. 25mm。 Compared with conventional type thermocouple, it has the following advantages of small volume, no internal air gap and thermal inertia, the measured value after small mechanical performance is good, resistance to vibration, impact resistant to bending, easy to install and use long life end thermocouple end thermocouple temperature sensing element resistance wire winding by special processing, close to the face in the thermometer. Compared with general axial thermocouple, it can more accurately and quickly to reflect the actual temperature of end face, suitable for measuring the bearing and other parts of the face flameproof thermocouple temperature through the special structure of the junction box, put the shell internal explosive mixed gas by affected by sparks or electric arc explosion limit within the junction box, that wouldn't make production field explosion. Flameproof thermocouple can be used in the bla B3c level zone with explosion danger place temperature measurement. Pt100: used for thermocouple, thermocouple, temperature meter, temperature transmitter, pressure differential pressure transmitter, hot runner heater, compensation cable, control cable, etc.