Thermal resistance works

发布时间：2022-02-24 : 流览次数： 122

 Industrial thermal resistance composition

       The industrial heat resistance is mainly composed of a junction box protection tube, a terminal, an insulating sleeve, and a temperature sensing element, and is composed of various mounting and fixing devices. The junction box is mainly in the form of a waterproof type, a socket type and a small junction box.

       Industrial thermal resistance works

       The working principle of the industrial thermal resistance is to measure the temperature by utilizing the self-resistance of the temperature sensing element as the temperature changes. If used in conjunction with display meters and recording meters, the temperature corresponding to the resistance can be displayed. When there is a temperature gradient in the measured medium, the measured temperature is the average temperature in the dielectric layer within the temperature sensing element range.

       Type of industrial thermal resistance

       Platinum thermal resistance: Widely used to measure temperatures in the (-200 to 850)°C range. In a few cases, the low temperature can be measured to 1K, and the high temperature can be measured to 1000°C. Its physical and chemical properties are stable and its reproducibility is good, but it is expensive. Platinum thermal resistance is approximately linear with temperature.

       Copper thermal resistance: Widely used to measure temperatures in the (-50 to 150)°C range. The advantage is that the high purity copper wire is easy to obtain, the price is cheap, the interchangeability is good, but it is easy to oxidize. Copper thermal resistance is linear with temperature.

       Armored thermal resistance: It is developed on the basis of armored thermocouple. It is made of a combination of thermal resistance, insulating material and metal sleeve. Its characteristic is that the external dimensions can be made small (minimum diameter can be achieved 20mm), so the reaction speed, good mechanical properties, vibration resistance, impact resistance, good flexibility, and not susceptible to the erosion of harmful media.

       Industrial thermal resistance precautions

       1, before using the thermal resistance must check its good ring, a simple check method is to pull the thermal resistance from the protective tube, measure its resistance with a multimeter. If the multimeter reads “0” or the multimeter reading is less than the R0 value, the RTD is short-circuited and a short-circuit must be found to repair it; if the multimeter reads “∞”, the RTD has been disconnected and cannot be used; if the multimeter reads The resistance value is higher than R0, indicating that the thermal resistance is normal.

       2. When the resistance value of the thermal resistance is not correct, the resistance wire should be increased or decreased from the intersection of the lower end points instead of being adjusted from other places. After completely adjusting, the resistance wire should be arranged neatly and cannot be touched. It is still wrapped as it is. The repaired thermal resistance must be qualified before being used.

       3. When the thermal resistance is installed, its insertion depth is not less than 8 times to 10 times the outer diameter of the thermal resistance protection tube, and the heat resistance of the thermal resistance is increased as much as possible. The thermal resistance is mounted as vertically as possible to prevent bending at high temperatures. In order to reduce the error caused by radiant heat and heat conduction during use, the thermal resistance should be as close as possible to the temperature of the surface of the protection sleeve and the measured medium, and the black coefficient of the thermal resistance protection sleeve should be reduced.

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