What is the difference between standard platinum resistance and armored thermal resistance

Although armored thermal resistors are widely used in industry, their application is limited by their temperature measurement range. The temperature measurement principle of thermal resistors is based on the characteristic that the resistance value of a conductor or semiconductor changes with temperature. It has many advantages, such as remote transmission of electrical signals, high sensitivity, strong stability, good interchangeability and accuracy, but it requires power excitation and cannot measure temperature changes instantaneously. Industrial thermal resistors generally use Pt100, Pt10, Cu50, Cu100, and the temperature measurement range of platinum thermal resistors is generally minus 200-800℃, and that of copper thermal resistors is minus 40 to 140℃. Thermal resistors are classified into types like thermocouples, but they do not require compensation wires and are cheaper than thermocouples.
In my country, standard platinum resistance thermometers have been widely used. In particular, the second-class standard platinum resistance thermometer with quartz outer sheath is widely used in the value transfer and precision temperature measurement of temperature measurement laboratories at all levels. There are two types of outer sheaths for standard platinum resistance thermometers, quartz outer sheaths and metal outer sheaths. Quartz outer sheathed standard platinum resistance thermometer and metal outer sheathed standard platinum resistance thermometer each have their own advantages and disadvantages. The specific choice of which thermometer should be determined according to the actual situation of the user. Generally speaking, the stability that can be achieved by quartz outer sheathed standard platinum resistance thermometer is better than that of metal outer sheathed standard platinum resistance thermometer. Therefore, so far, the grade of quartz outer sheathed standard platinum resistance thermometer can be working standard, first class or second class, while the grade of metal outer sheathed standard platinum resistance thermometer is usually second class. However, the advantage of metal outer sheathed standard platinum resistance thermometer is that it is not easy to damage and can be used in many non-acidic media, metal temperature blocks or harsh environments. This is very important because standard platinum resistance thermometers are usually irreparable after being damaged.

Ordinary thermal resistor

From the temperature measurement principle of thermal resistor, it can be seen that the change of the measured temperature is directly measured by the change of the resistance value of the thermal resistor. Therefore, the change of the resistance of various wires such as the lead wire of the thermal resistor body will affect the temperature measurement.

The armored thermal resistor is a solid body composed of a temperature sensing element (resistor), lead wire, insulating material, and stainless steel sleeve. Its outer diameter is generally φ2-φ8mm, and the minimum can reach φ0.25mm. Compared with ordinary thermal resistors, it has the following advantages:

① Small size, no air gap inside, thermal inertia, and small measurement value;

② Good mechanical properties, vibration resistance, and impact resistance;

③ Can be bent and easy to install;

④ Long service life.

Armored thermal resistors are commonly used temperature measuring elements in temperature measuring instruments. When the two ends of two conductors of different components are connected into a loop, when the temperatures of the thermocouples at the two junctions are different, a thermal current will be generated in the loop. If there is a temperature difference between the working end and the reference end of the thermocouple, the display instrument will indicate the temperature value corresponding to the thermoelectric potential generated by the thermocouple.

Armored thermal resistance couple is a temperature sensor. It has a smaller diameter than assembled thermocouples, is easy to bend, has good shock resistance, and is suitable for installation in places where assembled thermocouples cannot be installed. The armored thermocouples produced by the company use imported thermal resistance temperature measuring elements. Therefore, it has the advantages of accuracy, sensitivity, fast thermal response time, stable quality, and long service life.