Thermocouples and thermal resistors are the most common and most commonly used in industrial temperature measurement and control, and both belong to contact temperature measurement in temperature measurement. But the two are different in principle, wiring method and temperature measurement range.
The international regulations for thermocouples are divided into B, R, S, K, N, E, J, and T. Among them, B, R, and S belong to platinum series thermocouples, and platinum belongs to precious metals. They are also called noble metal thermocouples. Divided into ordinary type and armored type. Ordinary thermocouples are generally composed of thermal electrodes, insulating tubes, protective sleeves, and junction boxes. Armored thermocouples are assembled by combining thermocouple wire, insulating material and metal protective sleeve. It is a solid combination made by drawing.
Thermal resistance is divided into:
The resistance change of the common type thermal resistance lead-out wire or various wires will affect the temperature measurement;
The outer diameter of the armored thermal resistance is generally 2-8mm, which has advantages over ordinary types: flexibility, small size, good mechanical properties, shock resistance, impact resistance, small hysteresis in thermal inertia measurement, and long service life;
紧贴温度计端面，适用于测量轴瓦和其他机件的端面温度； The end surface thermal resistance is close to the end surface of the thermometer, which is suitable for measuring the end surface temperature of bearing pads and other parts;
Explosion-proof thermal resistance adopts explosion-proof junction box.
Difference in temperature range:
1.Temperature range of thermal resistance -270 ℃ -1800 ℃
2. Industrial thermal resistance usually uses Pt100, Pt10, Cu50, Cu100;
The temperature range of platinum thermal resistance is generally minus 200-800 degrees Celsius.
Copper thermal resistance is minus 40 to 140 degrees Celsius.
接线方式区别： End-type thermocouple (resistance) wiring method difference:
First, the materials of thermocouples are generally more expensive. When the distance is long, in order to save material costs and reduce costs, compensation wires (compensating and extending) are usually used for transmission. ps: Pay attention to the matching of the models. Do not connect the wrong polarity.
Second, the thermal resistance wiring method has two wire, three wire, four wire system wiring
1. The two-wire system is suitable for situations that do not require precise temperature. It can be used to measure the resistance of the wire in advance, and the temperature is deducted from the measurement result. It is a rough compensation method.
2. The three-wire system is a more common and professional temperature measurement, eliminating the premise of wire resistance: the same material, the same wire diameter, and the same length.
3. The four-wire system is more complicated and is generally not used.
性能特点区别： Performance characteristics of end face thermocouple (resistance) :
1. The main features of thermocouples are wide temperature measurement range, stable performance, simple structure and good dynamic response. It can transmit 4-20mA electric signals remotely, which is convenient for automatic control and centralized control.
2. The thermal resistance also has many advantages. It can also transmit electric signals remotely, with high sensitivity, strong stability, interchangeability and accuracy. However, it requires power supply excitation and cannot measure temperature changes instantaneously.