Performance of armored thermal resistance temperature measurement system in practical application

Armored thermal resistors measure temperature by using the property that the resistance of metal conductors or semiconductors changes with temperature. The heated part of the thermal resistor (temperature sensing element) is formed by winding fine metal wire evenly around a skeleton made of insulating material or on a substrate through a laser sputtering process. When the measured medium has a temperature gradient, the measured temperature is the average temperature of the medium layer within the range of the temperature sensing element. The armored thermal resistor temperature measurement system generally consists of thermal resistors, connecting wires and display instruments. The following two points must be noted:
① The thermal resistor and the display instrument must have the same graduation number
② In order to eliminate the influence of the change in the resistance of the connecting wire, a three-wire connection method must be used.
(2) Armored thermal resistors Armored thermal resistors are solid bodies composed of temperature sensing elements (resistance bodies), leads, insulating materials, and stainless steel casings. Its outer diameter is generally φ2~φ8mm, and can be as small as φmm.
Compared with ordinary thermal resistors, it has the following advantages: ① Small size, no air gap inside, small measurement lag in thermal inertia; ② Good mechanical properties, vibration resistance, and impact resistance; ③ Can be bent, easy to install ④ Long service life.
(3) End face thermal resistor The end face thermal resistor temperature sensing element is wound with specially treated resistance wire and is close to the end face of the thermometer. Compared with general axial thermal resistors, it can more accurately and quickly reflect the actual temperature of the measured end face, and is suitable for measuring the end face temperature of bearings and other parts.
(4) Flameproof thermal resistor The flameproof thermal resistor uses a specially structured junction box to isolate the explosive mixed gas inside its shell from the effects of sparks or arcs.
The circuit breaker repair of the resistor body will inevitably change the length of the resistor wire and affect the resistance value. Therefore, it is better to replace the resistor body with a new one. If welding is used for repair, it must be calibrated and qualified before use.