How to correctly choose all kinds of transmitter: integration of bimetallic thermometer

Sensor and transmitter in instruments, meters and plays an important role in industrial automation field. Unlike sensor, transmitter in addition to convert non-electricity into measurable quantity, general also has certain effect. One of the following a brief introduction of the integration of the rational choice of bimetallic thermometer. Integration of bimetallic thermometer integrated bimetallic thermometer is the perfect combination of temperature sensor and transmitter, the - in very simple way 200 ~ + 1600 ℃ temperature in the range of the signal is converted to a two wire 4 ~ 20 ma DC electrical signal transmission to display, regulator, recorder, DCS, etc. , it can realize accurate measurement and control of temperature. Integration of bimetallic thermometer is the modern industrial field, the update products, scientific research institutes temperature measurement and control is necessary for collecting and distributing system, digital bus system. Integration with thermal resistance and thermocouple bimetallic thermometer is generally divided into two types. The integration of bimetallic thermometer is general by temperature measuring probe ( The thermocouple or heat resistance sensor) And the two wire system solid electronic units. In the form of solid module temperature measuring probe directly installed on the terminal box, thus forming the integration of the transducer. Thermal resistance bimetallic thermometer is the R/V conversion unit, the benchmark unit, linear circuit, reverse connect protection, current limiting protection, V/I conversion unit, etc. Measuring temperature resistance signal amplification, and then by linear circuit of temperature compensate nonlinear relationship with the resistance, after the V/I conversion circuit outputs a measured a linear relationship with temperature and constant current signal of 4 ~ 20 ma. Thermocouple bimetallic thermometer generally by the reference source, the cold end compensation unit, amplification, linearization, V/I conversion, broken accidentally processing, reverse connect protection, current limiting circuit protection units. It is the cold junction compensation of thermocouple thermoelectric potential enlarged, cap again by linear circuits eliminate the nonlinear error of thermoelectric potential and temperature, the final amplification into 4 ~ 20 ma current output signal. In order to prevent the thermocouple measurement by thermocouple wire break and make the temperature control failure caused by accident, transmitter will also include a power protection circuit. When the thermocouple wire break or pick up solution, transmitter will output the maximum value ( 28mA） In order to make the instrument to cut off the power supply. Integration of bimetallic thermometer has simple structure, saves the wire, big output signal, strong anti-interference ability, good linear, simple display instrument, solid module earthquake moisture-proof, reverse connection protection and current limiting protection, reliable work, etc. The integration of the output of the bimetallic thermometer for unification of 4 ~ 20 ma signal; Can be used with microcomputer system or other conventional instrument match. Can also be user requirements in explosion-proof type or fire type measuring instrument. Next article: how to correctly choose all kinds of transmitter. 。 。 。 。 。 The article is: the pressure gauge protection grade interpretation and selection