What are the common faults of temperature measuring instrument?

The common failure of thermocouple thermometer is that the indicating value is low, or it stops at zero. This is because of the problem caused by thermocouple, which may be poor contact or open circuit, and generally there is no phenomenon of high indication.
In order to ensure the measurement accuracy, the cold end temperature compensation (commonly used compensation wire method) should be correctly conducted in use, and good insulation between the hot electrode and the Earth should be paid attention.
Common failures of thermal resistance thermometer: sometimes the pointer always points to the maximum. This is the disconnection of the temperature measuring element of the resistance thermometer, which makes the resistance infinitely large, or the two ends have poor contact and the contact resistance is large; another phenomenon is that the pointer points to the zero position, or deflects to the negative direction. The reason is that the temperature measuring element has a short circuit and the resistance is zero, or it is caused by the leakage or freezing of the resistance thermometer protective casing; another phenomenon is that the pointer does not move, which is because there is something wrong with the bridge itself, caused by no work.
In use, it is necessary to prevent moisture from entering the thermal resistance protective tube, and no open circuit or short circuit is allowed after the instrument is displayed. When checking the thermal resistance, the measured current should not be greater than 5mA.