The cause of thermocouple leakage and the solution is to _ the instrument

As chemical, petroleum, metallurgy, machinery and other departments of the rapid development of high precision, high sensitivity of the instrument is widely used, anti-interference problem will become problems that cannot be ignored, especially in industrial electric furnace, silicon carbide furnace, salt bath furnace, etc. The interference, cause operation of the instrument error increases, unstable and instructions at a slower pace, and so on. Must be resolved, otherwise can't guarantee the quality of our products and cause damage. Thermocouple leakage reason 1, electric furnace refractory brick in high temperature insulation fault, equipped with wire furnace furnace wall inserted with metal wire contact with thermocouple, thermocouple is easy to make furnace refractory brick is a good insulating material at room temperature, but as temperatures rise, insulation performance will decline significantly. Resistance furnace lining with alumina refractory brick for the most part, its resistance value also significantly reduced with temperature rise. 2, furnace wire contact with the thermocouple, platinum rhodium thermocouple protection tube is alumina ceramic tube, accidentally silk made separation insulation porcelain tube wear, under the high temperature insulation performance also want to reduce, cause leakage, then leaked to the thermocouple, so there is ac leakage on the thermocouple signals. The thermocouple leakage solution ( 1) Keep the thermocouple is not in contact with the refractory brick. ( 2) The thermocouple negative ground, eliminate the leakage on the thermocouple signal. ( 3) Add filter on the thermocouple output end device. ( 4) From the hot junction thermocouple leads to earth ground. ( 5) On the thermocouple tube and jacket heat-resistant steel pipe or carborundum tube, and make it grounded.