The selection of thermocouple method is _ instrument1

Thermocouple has many advantages, such as small volume, can bend, good mechanical performance, long service life, so it's a bigger role in people's life, its excellent features make it get the favor of people, but you must pay attention to the method in selecting. The characteristics of the thermocouple thermocouple thermal inertia small, response rapidly, such as maintenance tube fu 2 mm diameter common platinum resistance, the time constant of 25 s; The metal casing diameter - 2 mm of the thermocouple, the time often only about 5. Components and protection for the elastic compression at the bottom of the tube structure, the thermal response time shortened and further improve the vibration resistance. Thermocouple with flexible performance, kai with thermocouple in addition to the head, can make the direction of bending, so it is suitable for the structure is relatively complex, small temperature measurement equipment. Thermocouple long using life, kai in resistance of thermocouple by iron power twist of insulation materials cover and metal casing maintenance, thermocouple wire is not easy to jung corrosion by harmful medium, so it has normal thermocouple, thermocouple life with good resistance to vibration and shock resistance. Selection of thermocouple method according to the temperature range 500 ℃ or more generally choose thermocouple, usually selected thermocouple below 500 ℃; According to the accuracy of measurement choice: thermocouple with high accuracy requirement choice, to choose thermocouple accuracy is not high. According to the measurement range selection measured by thermocouple temperature generally refers to the 'point', generally refers to the space average temperature measured by thermocouple; 2 wire thermocouple wiring simple, but to bring in additional error lead resistance. So shall not apply to the manufacturing accuracy of grade a thermocouple, and when use and lead wires have shoulds not be too long. Wire system can eliminate the influence of the lead resistance, measurement accuracy is higher than 2 wire system. As the process of detecting element, its wide application. Wire system not only can eliminate the influence of the lead resistance, and the connection wire resistance phase at the same time, also can eliminate the influence of the resistance. When in high precision measurement, must use the four wire system. Thermocouple wiring, junction box opened the first, and then wiring. Connection way of general there are two wire and three-wire system two kinds. Three wire system has the advantage of cohesion, can prevent the bimetallic thermometer provoked by connecting wire resistance value of the instrument error value for show. Thermocouple appeared with the connecting wires should be insulated copper wire, shall not use the thermocouple compensating lead wires. Shows copper wire resistance should be according to the rules of data matching instrument technique conditions, the average of 2 a 50, dc balanced bridge wire resistance value can be used to adjust. Can't take a thermocouple with two instrument used in parallel, as long as the double branch thermocouple with appeared two instrument can only be used to apply. Thermocouple and its attachments without using, the required storage in tungsten-rhenium thermocouples are not affected by vibration and impact. Appropriate storage location condition is: 10 to ambient temperature 35 gc; Relative humidity is not more than 80%; Should not contain may form in the air around the thermocouple parts corrosion substance.