Thermocouple and thermal resistance, are used to measure the temperature.
Thermocouple is will two different kinds of metal or metal alloy welded together, constitute a closed loop, using thermoelectric potential principle to measure the temperature. When temperature difference at both ends of the thermocouple metal, the loop will produce thermoelectric EMFs, temperature difference is big, thermoelectric EMFs, thermo emf measurements using this principle to measure the temperature.
Thermocouple is positive and negative, so the need to ensure that these wires are connected to the correct polarity, otherwise it will cause significant measurement error in order to ensure reliable and stable thermocouple, installation requirements are as follows:
The welding of the two thermo electric poles of the thermocouple must be firm;
Two thermoelectric poles shall be insulated from each other so as to prevent the short circuit;
The connection of the compensating wire and the free end of the thermocouple is convenient and reliable;
The protective sleeve should be able to guarantee the thermode fully isolated from harmful medium;
The thermocouple is sensitive to outside interference, so the installation also need to consider the problem of shielding
Thermocouple and thermal resistance of the difference attributes of the hot resistance thermocouple signal properties of resistance signal voltage signal measuring range low temperature detection detection materials a metal material (a temperature sensitive to changes in the metal material) double metal materials in two different metal due to temperature change
The electric potential difference is generated at the ends of two different metals.
measuring principle
Resistance varies with the nature of temperature change to measure based on the pyroelectric effect to measure the temperature compensation 3 wire and four line connection internal compensation and external compensation cable contact resistance directly access requirements can be more precise avoid line loss to by compensating conductor direct access to the template; or compensating conductor received ginseng than the contact, and then in a copper wire received template
Comparison of thermocouple and thermal resistance
2 thermocouple type and available templates
2.1 thermocouple type
Depending on the use of materials, different types of thermocouples, to distinguish index number, indexing, temperature range, and on behalf of the each index number of thermocouple, the specific number of temperature much MV voltage output, thermocouple indexing, mainly the following.
Degree temperature range (c) two kinds of metal materials
B 0~1820 - platinum rhodium
C type 0~2315 tungsten 3 rare earth tungsten 26 rare earth
E type copper nickel nickel chromium - -270~1000
Type -210~1200 J iron copper nickel
K -270~1372 - type nickel chromium nickel silicon
Type -200~900 L iron copper nickel
Type N -270~1300 silicon - nickel chromium nickel silicon
R type -50~1769 Platinum Rhodium Platinum
S type -50~1769 Platinum Rhodium Platinum
Type -270~400 T copper nickel
Type -270~600 U copper nickel
