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    Temp Sensors

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    coolrsk17
    This document discusses different types of temperature sensors and their applications. The main types are thermocouples, resistance temperature detectors (RTDs), thermistors, infrared sensors, and semiconductors. Thermocouples are simple and rugged but less accurate, while RTDs are most accurate and stable over time but also more expensive. Thermistors have high sensitivity but a limited range. Infrared sensors allow non-contact temperature sensing but can be affected by environmental factors. Semiconductors are small and inexpensive but have a smaller measurement range. Each sensor type has advantages and disadvantages for different applications.

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    Temp Sensors

    Uploaded by

    coolrsk17
    70 views17 pages
    This document discusses different types of temperature sensors and their applications. The main types are thermocouples, resistance temperature detectors (RTDs), thermistors, infrared sensors, and semiconductors. Thermocouples are simple and rugged but less accurate, while RTDs are most accurate and stable over time but also more expensive. Thermistors have high sensitivity but a limited range. Infrared sensors allow non-contact temperature sensing but can be affected by environmental factors. Semiconductors are small and inexpensive but have a smaller measurement range. Each sensor type has advantages and disadvantages for different applications.

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    This document discusses different types of temperature sensors and their applications. The main types are thermocouples, resistance temperature detectors (RTDs), thermistors, infrared sensors, and semiconductors. Thermocouples are simple and rugged but less accurate, while RTDs are most accurate and stable over time but also more expensive. Thermistors have high sensitivity but a limited range. Infrared sensors allow non-contact temperature sensing but can be affected by environmental factors. Semiconductors are small and inexpensive but have a smaller measurement range. Each sensor type has advantages and disadvantages for different applications.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    70 views17 pages

    Temp Sensors

    Uploaded by

    coolrsk17
    This document discusses different types of temperature sensors and their applications. The main types are thermocouples, resistance temperature detectors (RTDs), thermistors, infrared sensors, and semiconductors. Thermocouples are simple and rugged but less accurate, while RTDs are most accurate and stable over time but also more expensive. Thermistors have high sensitivity but a limited range. Infrared sensors allow non-contact temperature sensing but can be affected by environmental factors. Semiconductors are small and inexpensive but have a smaller measurement range. Each sensor type has advantages and disadvantages for different applications.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 17

    Temperature Sensors

    Brief Overview
    Types

    of Sensors and how they work Applications and Disadvantages

    Sensor

    Advantages

    Types of Temperature Sensors

    Thermocouples Resistance Temperature Detectors (RTDs) Thermistors Infrared Sensors Semiconductors

    Thermocouples

    Two wires of different metal alloys. Converts thermal energy into electrical energy. Requires a temperature difference between measuring junction and reference junction. Easy to use and obtain.

    Thermocouple Applications
    Plastic injection molding machinery Food processing equipment Semiconductor processing Heat treating Medical equipment Industrial heat treating Packaging equipment

    Thermocouples
    Advantages Simple, Rugged High temperature operation Low cost No resistance lead wire problems Point temperature sensing Fastest response to temperature changes

    Disadvantages Least stable, least repeatable Low sensitivity to small temperature changes Extension wire must be of the same thermocouple type Wire may pick up radiated electrical noise if not shielded Lowest accuracy

    Resistance Temperature Detectors (RTDs)


    Wire wound and thin film devices. Nearly linear over a wide range of temperatures. Can be made small enough to have response times of a fraction of a second. Require an electrical current to produce a voltage drop across the sensor

    RTD Applications

    Air conditioning and refrigeration servicing Furnace servicing Foodservice processing Medical research Textile production

    RTDs
    Advantages Most stable over time Most accurate Most repeatable temperature measurement Very resistant to contamination/ corrosion of the RTD element

    Disadvantages High cost Slowest response time Low sensitivity to small temperature changes Sensitive to vibration (strains the platinum element wire) Decalibration if used beyond sensors temperature ratings Somewhat fragile

    Thermistors

    A semiconductor used as a temperature sensor. Mixture of metal oxides pressed into a bead, wafer or other shape. Beads can be very small, less than 1 mm in some cases. The resistance decreases as temperature increases, negative temperature coefficient (NTC) thermistor.

    Thermistors
    Most

    are seen in medical equipment markets. Thermistors are also used are for engine coolant, oil, and air temperature measurement in the transportation industry.

    Advantages
    High

    Thermistors

    Disadvantages

    sensitivity to small temperature changes Temperature measurements become more stable with use Copper or nickel extension wires can be used

    Limited

    range Fragile Some initial accuracy drift Decalibration if used beyond the sensors temperature ratings Lack of standards for replacement

    temperature

    Infrared Sensors

    An infrared sensor intercepts a portion of the infrared energy radiated by an object. Many types Optical Pyrometers, Radiation Pyrometers, Total Radiation Pyrometers, Automatic Infrared Thermometers, Ear Thermometers, Fiber optic Thermometers, Two-Color Pyrometers, Infra-Snakes, and many more.

    Infrared Applications

    Manufacturing process like metals, glass, cement, ceramics, semiconductors, plastics, paper, textiles, coatings. Automation and feedback control Improve safety in fire-fighting, rescues and detection of criminal activities. Used to monitor and measure human body temperatures with one second time response.

    Reliability and maintenance needs from building heating to electrical power generation and distribution

    Advantages

    Infrared Sensors

    Disadvantages

    No contact with the product required Response times as fast or faster than thermocouples No corrosion or oxidation to affect sensor accuracy Good stability over time High repeatability

    High initial cost More complex - support electronics required Emissivity variations affect temperature measurement accuracy Field of view and spot size may restrict sensor application Measuring accuracy affected by dust, smoke, background radiation, etc.

    Semiconductors
    Are

    small and result from the fact that semiconductor diodes have voltage-current characteristics that are temperature sensitive. Temperature measurement ranges that are small compared to thermocouples and RTDs, but can be quite accurate and inexpensive.

    Semiconductor Applications
    Hard

    Disk Drives Personal Computers Electronic Test Equipment Office Equipment Domestic Appliances Process Control Cellular Phones

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