【Daily Discussion】Utilities - Mechanical & Electrical - 20200723

Sensors designed based on the principle of metal expansion: Metals expand in response to changes in ambient temperature, and therefore sensors can convert this reaction into signals in various ways. Bimetallic strip sensor: A bimetallic strip is composed of two metals with different coefficients of expansion bonded together; as the temperature changes, material A expands more than the other metal, causing the strip to bend. The curvature of the bend can be converted into an output signal. Bimetallic rod and metal tube sensors: As the temperature rises, the length of the metal tube (material A) increases, while the length of the stainless steel rod (material B) does not change. As a result of this change in position, the linear expansion of the metal tube can be transmitted. Conversely, this linear expansion can be converted into an output signal. Sensors with deformation curve design for liquids and gases: When the temperature changes, liquids and gases also experience corresponding volume changes. Various types of structures can convert these changes in expansion into changes in position, thereby generating position-related outputs (potentiometers, sensing deviations, flow baffles, etc.). Resistive sensor: The resistance value of a metal changes as its temperature changes. For different metals, the change in resistance per degree of temperature variation varies, and the resistance value can be used directly as an output signal. Thermocouple sensor: A thermocouple consists of two metal wires made of different materials, which are welded together at one end. By heating this connection point, a potential difference appears in the areas that are not heated. The value of this potential difference is related to the temperature of the measurement point at the unheated area, as well as the material of these two conductors. This phenomenon can occur over a wide range of temperatures; by accurately measuring this potential difference and also the ambient temperature of the area that is not being heated, it is possible to determine the temperature at the heating point with precision. Since it must have conductors of two different materials, it is called a thermocouple.

Different types of sensors have different working principles as well. 1. Working principle of sensors designed based on the principle of metal expansion: Metals expand correspondingly when the ambient temperature changes; therefore, sensors can convert this reaction into signals in various ways. 2. Working principle of bimetallic strip sensors: A bimetallic strip is composed of two metals with different coefficients of expansion bonded together; as the temperature changes, Material A expands more than the other metal, causing the strip to bend. The curvature of the bend can be converted into an output signal. 3. Bimetallic rod and metal tube sensors: As the temperature rises, the length of the metal tube (material A) increases, while the length of the stainless steel rod (material B) does not change. As a result of this change in position, the linear expansion of the metal tube can be transmitted. Conversely, this linear expansion can be converted into an output signal. 4. Sensors with deformation curve design for liquids and gases: When the temperature changes, liquids and gases also experience corresponding volume changes. Various types of structures can convert these changes in expansion into changes in position, thereby generating position-related outputs (potentiometers, sensing deviations, flow baffles, etc.). 5. Resistance sensors: The resistance value of metals changes as the temperature changes. For different metals, the change in resistance per degree of temperature variation varies, and the resistance value can be used directly as an output signal. 6. Thermocouple sensor: A thermocouple consists of two metal wires made of different materials, which are welded together at one end. By heating this connection point, a potential difference appears in the areas that are not heated. The value of this potential difference is related to the temperature of the measurement point at the unheated area, as well as the material of these two conductors. This phenomenon can occur over a wide range of temperatures; by accurately measuring this potential difference and also the ambient temperature of the area that is not being heated, it is possible to determine the temperature at the heating point with precision. Since it requires two conductors made of different materials, it is called a thermocouple. 7. Working principle of infrared temperature sensors: In nature, when an object’s temperature is above absolute zero, the thermal motion within it causes it to continuously emit electromagnetic waves, including infrared rays with wavelengths ranging from 0.75 to 100 μm. Infrared temperature sensors are designed based on this principle. 8. Simulation of the working principle of a temperature sensor: The AD590 is a current-output type temperature sensor; its supply voltage range is 3–30V, the output current ranges from 223μA to 423μA, and its sensitivity is 1μA/℃. When a sampling resistor R is connected in series in the circuit, the voltage across R can be used as the output voltage. The resistance value of R should not be too high, in order to ensure that the voltage across the AD590 remains at least 3V. The transmission distance of the output current signal from the AD590 can reach over 1 km. As a high-impedance current source, it can reach up to 20MΩ, so there is no need to consider errors caused by the additional resistance introduced by select switches or CMOS multiplexers. Suitable for control of multi-point temperature measurement and remote temperature measurement. 9. Working principle of digital temperature sensors: Digital temperature sensors manufactured using silicon technology employ a PTAT structure; this semiconductor structure provides accurate, temperature-dependent output characteristics. The output of PTAT is modulated into a digital signal using a duty cycle comparator, and the relationship between the duty cycle and temperature is given by the formula: DC=0.32+0.0047*t, where t is in degrees Celsius. Since it outputs a digital signal, it is compatible with microprocessors MCU; by using the high-frequency sampling of the processor, it is possible to determine the duty cycle of the output voltage square wave signal, thereby obtaining the temperature. Due to its special manufacturing process, this temperature sensor boasts a resolution better than 0.005K. The measurement temperature range is from -45 to 130°C, which makes it widely used in high-precision applications.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, as well as changes in the value of thermal resistance, etc.; then, based on these relationships, the measured temperature is determined.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, as well as changes in the value of thermal resistance, etc.; then, based on these relationships, the measured temperature is determined.

Sensors designed based on the principle of metal expansion experience corresponding expansion when the ambient temperature changes; therefore, sensors can convert this reaction into signals in various ways. In a bimetallic strip sensor, the bimetallic strip is composed of two metals with different coefficients of expansion bonded together; as the temperature changes, material A expands more than the other metal, causing the strip to bend. The curvature of the bend can be converted into an output signal. In bimetallic rod and metal tube sensors, as the temperature rises, the length of the metal tube (material A) increases, while the length of the stainless steel rod (material B) does not increase. As a result of this change in position, the linear expansion of the metal tube can be transmitted. Conversely, this linear expansion can be converted into an output signal. Sensors with deformation curve designs for liquids and gases experience volume changes in response to temperature variations, as do the liquids and gases themselves. Various types of structures can convert these changes in expansion into changes in position, thereby generating position-related outputs (potentiometers, sensing deviations, flow baffles, etc.).

Changes in temperature cause the resistance value of sensitive elements (such as thermistors, thermocouples, etc.) to change, which in turn results in changes in the voltage output in the circuit.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, as well as changes in the value of thermal resistance, etc.; then, based on these relationships, the measured temperature is determined.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, as well as changes in the value of thermal resistance, etc.; then, based on these relationships, the measured temperature is determined.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, as well as changes in the value of thermal resistance, etc.; then, based on these relationships, the measured temperature is determined.

A temperature sensor is a sensor that can detect temperature and convert it into a usable output signal. Working principle of a temperature sensor: It relies on changes in temperature to cause variations in other measurable properties. Things like thermal expansion and contraction, changes in the value of thermal resistance, etc.; then, based on these changes, the measured temperature is determined