Since the thermocouple's thermal inertia causes the meter's indicated value to lag behind the measured temperature, this effect is particularly pronounced when performing rapid measurements. Therefore, thermocouples with thinner thermal electrodes and smaller protective tube diameters should be used whenever possible. The protective tube can even be removed when the temperature measurement environment permits.
In the use of hot and cold integrated control machine, usually use materials with good thermal conductivity, thin tube, small inner diameter protection sleeve, in the more precise temperature measurement, use unprotected sleeved bare wire thermocouple, but thermocouple It is easy to damage and should be corrected and replaced in time.
Due to the measurement lag, the amplitude of the temperature fluctuation detected by the thermocouple is smaller than the amplitude of the furnace temperature fluctuation. In order to accurately measure the temperature, a thermocouple with a small time constant should be selected. The time constant is inversely proportional to the heat transfer coefficient. It is proportional to the diameter of the hot end of the thermocouple, the density of the material, and the specific heat. If the time constant is to be reduced, In addition to the thermal coefficient, the error introduced by the insulation of the cold and heat integrated control machine is poor.
The hot and cold integrated control machine protects the tube and the wire plate from excessive dirt or salt residue, resulting in poor insulation between the thermocouple and the furnace wall, which is more serious at high temperatures, which not only causes the loss of the thermoelectric potential but also introduces interference. The error caused by this can sometimes reach Baidu.
The above installation failures should be avoided as much as possible to reduce the error rate of the integrated heat and cold control machine and save the operating cost of the enterprise.