Four common faults thermocouple problem is what _ instrument

Thermocouple is a kind of common temperature measuring instrument, the scope of application is also very extensive. All of the instruments in the process of using are there will be a certain fault, thermocouple is no exception, thermocouple is also there will be some problems when using. 1, fault phenomenon: display instrument indicates a negative; Possible reasons: the display instrument with thermocouple wiring is wrong or thermocouple have short circuit phenomenon; Processing method: correct wiring, or find out short circuit, reinforced insulation. 2, fault phenomenon: thermocouple table indicating infinity; Possible reasons: thermocouple or loosen the lead wire short circuit or terminal; Methods: the change in resistance or welding and tighten the screw connection, etc. 3, fault phenomenon: display of thermocouple indicated value is lower than the actual value or unstable value; Possible reasons: protecting tube with metal dust, dust, dirt and thermocouple short circuit between terminal; Methods: to remove scrap metal, cleaning dust, water, etc. , find the short circuit point reinforced insulation. 4, failure phenomenon: thermocouple value changes with the temperature relation; Possible reasons: thermocouple wire material corrosion metamorphism; To deal with the methods: replace thermocouple. Thermocouple elements in the use of what are the common fault in the thermocouple temperature measurement system generally consists of thermocouple, thermocouple wire and digital display table etc. In use must pay attention to the following two points: ( 1) Index number of thermocouple and display instrument must agree. In the DCS system I / 0 configuration should also pay attention to the index set. ( 2) As far as possible to eliminate the influence of the connection wire resistance change. The thermocouple itself has no problem, as long as careful observation field and changes in values, in order to find the cause of the problem. It is simple, really deal with the problem under some time. When problems occur, a corresponding index value table is indispensable. The indexing table to determine the temperature at the scene of the work is the first thing to do. Because here is the thermocouple elements and display instrument line, can be directly identified an element, secondary instrument and circuit which god out of the question. Also can appear in using thermocouple installation instructions will be low in some places, and in other places is normal phenomenon, many people think that is a thermocouple is broken, in fact, this is a manifestation of the practical experience less. Such as boiler coal mill outlet temperature measurement in our factory similar failure happen, just because of the protective sleeve tube has a very tiny sand holes. Is the negative pressure, because the pipe from sand holes breathing in cold air, cause the measured value is low. Solution is to replace a good casing in sealing, such already save money, and solved the problem. Thermocouple as a kind of common temperature measurement sensors, widely used in various industrial fields. Because of its simple principle not to, in the event of a problem, often confused, and directly replace thermocouple is used to deal with.