{"id":3294,"date":"2021-08-07T09:35:44","date_gmt":"2021-08-07T05:05:44","guid":{"rendered":"https:\/\/davvarenergy.com\/?page_id=3294"},"modified":"2022-05-24T14:55:24","modified_gmt":"2022-05-24T10:25:24","slug":"thermocouple","status":"publish","type":"page","link":"https:\/\/davvarenergy.com\/en\/products\/temperature-measurement\/thermocouple\/","title":{"rendered":"thermocouple"},"content":{"rendered":"
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Thermocouple<\/span><\/strong><\/span><\/p>\n Temperature is one of the most measured of the physical quantities, so measuring it correctly is important. If there is temperature gradient in an electrical conductor, the energy (heat) \ufb02ow is associated with an electron \ufb02ow along the conductor, and an electromotive force (emf) is then generated in that region. Both the size and direction of the emf are dependent on the size and direction of the temperature gradient itself \u2013 and on the material forming the conductor. The voltage is a function of the temperature difference along the conductor length. For the historians among you, this effect was discovered by TJ seebeck in 1822.<\/span><\/p>\n The output voltage of a single conductor, as shown, is not, however, normally measurable since the sum of the internal emfs around a completed circuit in any temperature situation is zero. So, in a practical thermocouple temperature sensor, the trick is to join two materials having different thermoelectric emf\/ temperature characteristics in order to produce a usable net electron \ufb02ow and a detectable net output voltage.<\/span><\/p>\n Thus, two connected dissimilar conductors, a and b, are exposed to the same temperature gradients. basically, there is a net electron \ufb02ow across the junction caused by the different thermoelectric emfs, in turn resulting from the interaction of the gradient with the two different conductors.<\/span><\/p>\n Thermocouple Types, Standards And Reference Tables<\/span><\/p>\n Many combinations of materials have been used to produce acceptable thermocouples, each with its own particular application spectrum. However, the value of interchangeability and the economics of mass production have led to standardisation, with a few speci\ufb01c types now being easily available, and covering by far the majority of the temperature and environmental applications.<\/span><\/p>\n These thermocouples are made to conform to an emf\/ temperature relationship speci\ufb01ed in the form of tabulated values of emfs resolved normally to 1 \u03bcv against temperature in 1\u00b0C intervals, and vice versa. Internationally, these reference tables are published as IEC 60584.1 (BS EN 60584.1). it is worth noting here, however, that the standards do not address the construction, or insulation of the cables themselves or other performance criteria. With the diversity to be found, manufacturers\u02be own standards must be relied upon in this respect.<\/span><\/p>\n