Thermistor SensorThe primary component is a thermistor, which absorbs radiant heat when there is thermal radiation around the thermosensitive material, causing the temperature to rise and subsequently altering the resistance value of the material.
Thermistor sensors, commonly used to measure temperature, are generally simple in structure and affordably priced. Thermistors without an external protective layer are suitable only for dry environments; sealed thermistors are resistant to moisture corrosion and can be used in harsh conditions. Due to the high resistance of thermistor sensors, the resistance of the connecting wires and the contact resistance can be neglected, allowing them to be used for long-distance temperature measurements of up to several kilometers. Measurement circuits often use bridge configurations. Their principle can also be applied to other temperature measurement and control circuits.
Thermistor sensors can compensate for the humidity of certain materials within a specific temperature range. For instance, the moving coil of a moving coil meter is typically made of copper wire. As the temperature increases, the resistance also increases, leading to temperature errors. Therefore, a thermistor with a negative temperature coefficient can be connected in parallel with manganese copper wire resistance in the moving coil circuit, then串联with the material to be compensated, effectively canceling out errors caused by temperature changes. Thermistors are also commonly used to form compensation circuits in transistor circuits and logarithmic amplifiers, to offset drift errors caused by temperature variations.
Overheat maintenance is directly connected to direct maintenance. In low current scenarios, thermistor sensors can be directly connected in series with the load to prevent overheating damage and maintain equipment. In high current situations, it can be used for the maintenance of relays, transistor circuits, and more. In any case, the thermistor is closely integrated with the equipment being maintained, allowing for sufficient heat exchange between them. Once overheating occurs, the thermistor triggers protective measures. For instance, a sudden-change thermistor sensor is embedded in the stator winding of an electric motor and connected in series with a relay. When the motor is overloaded, the stator current increases, causing heating. When the temperature exceeds the sudden-change point, the current in the circuit can abruptly change from a few milliamperes to several tens of milliamperes, causing the relay to activate and then perform overheat protection.
Please provide the Chinese content to be translated.Thermistor sensorApplying a specific heating current, its surface temperature will be higher than the surrounding air, at which point its resistance is lower. When the liquid level is above the device's height, the liquid will carry away its heat, causing it to cool down and increase resistance. By detecting the change in resistance, one can determine if the liquid level is below the set value. The oil level alarm sensor in car fuel tanks is manufactured using this principle. Thermistors are also used in cars to measure oil temperature and coolant mixture.
