How to choose NTC temperature sensor.PPTC Thermistor Vendor

　　As we all know, NTC temperature sensor is a commonly used temperature measuring instrument, which is widely used in many industries. Therefore, when purchasing an NTC temperature sensor, it is necessary to consider many aspects. If the purchased NTC temperature sensor is not suitable, it will easily cause certain damage during use. So how do we choose it? The following comprehensive practical experience of our Shenzhen Precision Sensor Co., Ltd. is described as follows.

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　　First: According to the different working temperature range of the application, the material is selected. The NTC temperature sensor is used as a sensitive component for temperature measurement. It is very important to choose different materials according to its different working temperature range. The sensor is generally composed of a temperature sensing head (metal shell). (or plastic shell), wires, terminals and connectors, epoxy resin or other filling materials, etc. Different materials should be selected according to different working environment temperatures. For example, if the working temperature is within 105 degrees, we will choose temperature-resistant 105 degree PVC wire, if the working temperature is up to 125 degree, we will choose the irradiation wire with temperature resistance of about 125 degree. When the temperature is as high as 200 degree, we will use Teflon wire or silicone wire.

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　　Second, select the type according to the accuracy of temperature measurement required in the workplace. Accuracy is an important performance index of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the entire measurement system. There are two factors that determine the accuracy of the NTC temperature sensor: one is the error of the thermistor itself. The thermistor The smaller the B value error, the higher the measurement accuracy. The second is the contact method between the temperature sensing head of the sensor and the temperature measurement object. The measurement accuracy of direct contact is higher than that of indirect contact. The R-T curve is non-linear. It is impossible to guarantee the same accuracy over a wide range of operating temperatures. Therefore, in order to obtain higher measurement accuracy, select the central working temperature point of the workplace (generally the central working temperature point The accuracy is the highest. According to the discreteness of the R-T curve, the farther the temperature point is from the central working temperature point, the accuracy error will gradually increase). .

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　　Third: select the type according to the sensitivity required by the working occasion used. Different applications require the response speed of the NTC temperature sensor to be different. And different materials have different thermal conductivity. The response speed of the NTC temperature sensor is affected There are several factors: First, the thermal time constant of the thermistor chip. The thermal time constant is small and the response speed is fast. The second is the thermal conductivity of the temperature sensing head shell material. Materials with high thermal conductivity have excellent thermal conductivity. The size of the temperature sensor head, the size of the temperature sensor head is small, the heat conduction time will be correspondingly shorter, and the reaction speed will be faster. Fourth, the thermal conductive glue filled inside the temperature sensor head. The temperature sensor head is filled with thermal conductive silicone grease with high thermal conductivity It will react faster than unfilled\filled thermal grease with low thermal conductivity.

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　　Fourth: select the type according to the difference of the measurement object and the measurement environment. Different working environments have different temperature and humidity conditions. Different measurement objects also have different requirements. (such as water temperature measurement, human body temperature measurement, etc.), so , which requires the NTC temperature sensor to have good insulation. When selecting the type, when considering the temperature range of the working environment, it is also necessary to take into account the humidity of the working environment, whether it is exposed to water or water vapor, whether it is exposed to Human body, with or without pressure resistance requirements.... Different materials have different adhesion, sealing and temperature resistance characteristics. For example: The most common filling material for NTC temperature sensors-----epoxy resin, epoxy resin has Good sealing and adhesion, the temperature resistance can be as high as 150 degrees. But its adhesion to the metal shell is weaker than that of plastic materials. Compared with the adhesion to the wire, the combination of epoxy resin and PVC wire is dense Therefore, when selecting materials, it is not that the material with higher temperature resistance is better, as long as it is a material that satisfies the working temperature range and has adhesion to the filling material The best material is the best.

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　　Fifth: Pay attention to the stability of the NTC temperature sensor. The ability of a temperature sensor to keep its performance unchanged after a period of use is called stability. The factors that affect the long-term stability of the sensor include the stability and reliability of the NTC thermistor chip, the sensor itself and its structure, and the use environment of the sensor. To make the sensor have good stability, the sensor must have strong environmental adaptation. ability. The confirmation of stability starts from the following three aspects: First, select a highly reliable thermistor chip as the core. Second, select a reasonable structure and have strong mechanical strength. Third, select different fill material.

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