Detailed description of socket thermal resistance
又叫插座式铂热电阻。 Socket-type thermal resistance is also called socket-type platinum thermal resistance. Socket-type thermal resistance temperature measurement is based on the characteristic that the resistance value of a metal conductor increases with increasing temperature. Most of the thermal resistances are made of pure metal materials. At present, the most widely used are platinum and copper in the form of connectors, which are easy to install. Socket-type platinum thermal resistance elements are made of micro-ceramic tubes and wound platinum thermal resistance wire birth coils inside holes. The temperature sensing elements are made relatively small (the minimum outer diameter can be Ф1.6 ～ Ф1. 2mm) It is made into various miniature temperature sensor probes. Suitable for measuring temperature of liquid, gas and solid surface in the range of -200- + 450 ℃. WZP-260 WZP-270 WZP-280 series socket-type thermal resistors are produced in accordance with China's new standard JB / T8622-1997. Its working principle is that under the action of temperature, the resistance value of the platinum resistance wire changes with the change of temperature. The relationship between temperature and resistance is close to a linear relationship, the deviation is extremely small, and as time increases, the deviation is ignored, and the electrical performance is stable. This series of products have the advantages of small structure, wide range of use, good reliability, short thermal response time, etc., and can form a variety of products with multiple specifications for petroleum, chemical, power station, metallurgy, light industry, food, textile, medical and health , Scientific research, agriculture, and machinery industries provide a new generation of high-quality products.
的接线方式有哪几种 What are the wiring methods of socket thermal resistance
Thermal resistance is a primary element that converts temperature changes into resistance changes. Usually, resistance signals need to be transmitted to computer control devices or other primary instruments through leads. Industrial thermal resistance is installed at the production site, and there is a certain distance from the control room, so the lead of the thermal resistance will have a greater impact on the measurement results.
There are three main ways of thermal resistance lead
1 Two-wire system: The method of connecting a wire at each end of the thermal resistor to draw a resistance signal is called a two-wire system: This method of wiring is very simple, but because the wire must have a wire resistance r, the size of r and the material and length of the wire Related factors, so this lead method is only suitable for occasions with low measurement accuracy
2 Three-wire system: The method of connecting a lead to one end of the root of a thermal resistor and connecting two leads to the other end is called a three-wire system. This method is usually used in conjunction with a bridge to better eliminate the effect of lead resistance. The most commonly used in industrial process control.
3 Four-wire system: The method of connecting two wires at each end of the root of a thermal resistor is called a four-wire system, of which two leads provide a constant current I for the thermal resistor, convert R to a voltage signal U, and then pass the other two The lead leads U to the secondary meter. It can be seen that this lead method can completely eliminate the resistance effect of the lead and is mainly used for high-precision temperature detection.
采用三线制接法。 Socket-type thermal resistance adopts three-wire connection method. The three-wire system is used to eliminate measurement errors caused by the resistance of the connecting wires. This is because the circuit for measuring thermal resistance is generally an unbalanced bridge. The thermal resistance is a bridge arm resistance of the bridge, and its connecting wire (from the thermal resistance to the central control room) also becomes a part of the bridge arm resistance. This part of the resistance is unknown and changes with the ambient temperature, causing measurement errors. The three-wire system is used to connect one lead to the power supply terminal of the bridge, and the other two to the bridge arm where the thermal resistance is located and the bridge arm adjacent to it, which eliminates the measurement error caused by the line resistance.