A temperature transducer is an electrical device that measures temperature through the conversion of thermal energy into a physical quantity, such as displacement, pressure or an electrical signal. This process allows for the automatic measuring and recording of temperature measurements. The primary function of a temperature transducer is to measure and convert thermal energy into a readable form, enabling the user to accurately measure temperature. Temperature transducers are used in a variety of industries, such as automotive, medical, and manufacturing, for their precise temperature measurement capabilities.
The following are the features of the temperature transducer.
• The input is always a measure of temperature.
• Transducer mainly converts thermal energy into an alternating electrical signal.
• Thermometers are used to measure the temperature and heat flow of devices.
Sensing Element
The temperature transducer utilizes a sensing element that is capable of responding to changes in temperature. A common example of this is a resistance thermometer, which uses platinum metal as the sensing element. This component is designed to change its characteristics depending on the temperature, allowing it to accurately detect and measure temperature.
• The temperature sensing element converts the temperature into an electrical signal that is proportional to the amount of heat.
• The effect of temperature on resistance should be significant.
• The sensing element must have a high resistance value.
Types of Temperature Transducer
Contact Temperature Sensor Device
In this type of transducer, the sensing element is directly connected to the thermal source, allowing heat to be transferred through the process of conduction. This process involves the transfer of heat from one substance to another without requiring any movement of the substance.
Non-contact Type Temperature Sensor Device
A non-contact type transducer uses convection to transfer heat from a thermal source to a sensing element without direct physical contact. Convection is the process of heat transfer by the movement of a substance, making it an ideal method for non-contact temperature measurement. Non-contact transducers can be further divided into categories such as radiation thermometry, acoustic thermometry, and infrared thermometry. Radiation thermometry uses electromagnetic radiation to measure temperature, acoustic thermometry measures temperature changes in sound waves, and infrared thermometry measures infrared radiation emitted by an object to calculate its temperature.
The thermistor is a type of resistor that has a resistance that changes depending on the temperature. To measure this resistance, a small current is passed through the thermistor and the voltage drop across the resistor is then measured. This allows for the resistance to be calculated, and thus the temperature can be determined.
The resistance thermometer is categorized into two types.
- Negative Temperature Coefficient (NTC) is used to detect changes in temperature.
- The Temperature Position Coefficient is used to regulate the current.
Resistance Thermometer
The resistance of metal is a thermometric property that changes with temperature, making it an ideal material for use in a resistance thermometer. The resistance thermometer is a device used for the precise measurement of temperature, usually in laboratory conditions. Platinum is the most common material used as the sensing element in resistance thermometers due to its high resistance-temperature coefficient. This property allows the resistance thermometer to accurately measure the temperature of its environment.
Thermocouples
The thermocouple works by generating an electrical voltage in response to a temperature difference. This is accomplished by connecting two different types of metal together in a circuit. When the temperature changes at the point of contact between the two metals, the voltage produced changes accordingly. This voltage is proportional to the temperature difference between the two metals. The thermocouple is therefore an efficient way to measure temperature by converting the thermal energy into electrical energy.
Integrated Circuit Temperature Transducer
The IC temperature transducer is a device which combines a temperature sensing element and an electronic circuit to measure temperature. It has a linear characteristic and a limited operating range of 0ᵒ to 200ºC. This is one of the major disadvantages of the transducer, as it cannot measure temperatures outside this range.