What is a metal thermal resistor sensor?

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What is a Metal Thermistor Sensor?
Thermistor flowmeter is made based on the phenomenon of heat conduction inside the medium in physics. If a thermistor with a temperature of t1 is placed in a medium with a temperature of t2, and the surface area of ​​the thermistor in contact with the medium is a, the heat dissipated by the thermistor can be expressed as: q=ka(t1-t2), where k is the thermal conductivity coefficient, or heat transfer coefficient. Experiments have shown that k is related to parameters such as the density, viscosity, and average flow rate of the medium. When other parameters are constant, k is only proportional to the average flow rate of the medium. By measuring the heat dissipated by the thermistor, the average flow rate or flow rate of the medium can be measured. Thermistor sensors have the advantages of small size, fast response speed, and high sensitivity, so they are widely used in many fields.

Thermistor sensors are widely used in industry. Depending on the product model, their scope of application is also different. Specifically, there are the following aspects: Thermistor sensor temperature measurement: Thermistor sensors used to measure temperature are generally simple in structure and relatively cheap. Thermistors without an outer protective layer can only be used in dry places; sealed thermistors are not afraid of moisture erosion and can be used in harsh environments. Since the resistance of thermistor sensors is large, the resistance of the connecting wires and the contact resistance can be ignored. Therefore, thermistor sensors can be used in long-distance temperature measurement of several thousand meters, and the measurement circuit mostly uses a bridge circuit. Its principle can also be used for other temperature measurement and temperature control circuits. Thermistor sensors are used for temperature compensation: Thermistor sensors can compensate for the humidity of certain components within a certain temperature range. For example, the moving coil in the moving coil instrument head is wound with copper wire. As the temperature rises, the resistance increases, causing temperature errors. Therefore, the negative temperature coefficient thermal resistor can be connected in parallel with the manganese copper wire resistor in the moving coil circuit and then connected in series with the compensated components to offset the error caused by temperature changes. In transistor circuits and logarithmic amplifiers, thermistors are also often used to form compensation circuits to compensate for drift errors caused by temperature. Overheat protection of thermistor sensors: Overheat protection is divided into direct protection and indirect protection. For low current applications, thermistor sensors can be directly connected in series with the load to prevent overheating damage and protect the device. For high current applications, they can be used to protect relays, transistor circuits, etc. In either case, the thermistor is closely integrated with the protected device, so that the two can fully exchange heat. Once overheated, the thermistor plays a protective role. For example, a mutation type thermistor sensor is embedded in the stator winding of the motor and connected in series with the relay. When the motor is overloaded, the stator current increases, causing heat. When the temperature is greater than the mutation point, the current in the circuit can suddenly change from a few tenths of milliamperes to tens of milliamperes, so the relay is activated to achieve overheating protection. Thermistor sensors are used to measure liquid levels: When a certain heating current is applied to the NTC thermistor sensor, its surface temperature will be higher than the surrounding air temperature, and its resistance value is small at this time. When the liquid is higher than its installation height, the liquid will take away its heat, causing its temperature to drop and its resistance value to increase. By judging its resistance change, you can know whether the liquid level is lower than the set value. What is a metal thermal resistor sensor?

Thermal resistor temperature measurement principle

It is based on the characteristic that the resistance value of a conductor or semiconductor changes with temperature to measure temperature and temperature-related parameters. Thermal resistors are mostly made of pure metal materials. Currently, platinum and copper are more commonly used. Now, materials such as nickel, manganese and rhodium have begun to be used to manufacture thermal resistors. Thermal resistors usually need to transmit resistance signals to computer control devices or digital displays through leads.