thermostat

Application

Temperature Sensor Characteristics

Learn more about the characteristics for different types of temperature sensors and their typical applications.

In a perfect world, product design from initial concept to production release is a straight line, with no wasted engineering capacity, purchasing time, or redesigns required by design changes. In the real world, the path to product release is much more circuitous, where the path to product release almost serpentine at times. We believe the preferred timing for temperature sensor design involvement is during product concept. This allows our temperature sensor design engineers to take an active role in product design, offering our years of thermal design experience. 

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A negative temperature coefficient (NTC) thermistor is a temperature sensor that uses the resistance properties of ceramic/metal composites to measure the temperature.  With thermo-sensitive materials, its resistance decreases as temperature increases, meaning that it is extremely sensitive to temperature movement without causing thermal load. Our portfolio of NTC thermistors offer many advantages in temperature sensing including: miniature size, excellent long-term stability, high accuracy and precision.

discrete ntc thermistor

Applications

  • The medical industry relies on NTC’s in various applications including catheters, dialysis equipment, and patient monitoring.
  • Appliances from dryers to coffee makers use NTC thermistors to accurately measure temperature.
  • HVAC and refrigeration equipment use NTC sensors to measure temperature in building controls and processes, resulting in increased efficiency and better comfort.
  • The electrification of the automobile is driving demand for temperature sensors to improve the efficiency and safety of hybrid and electric vehicles.

 

One rapidly growing application for NTC sensor assemblies is in the field of disposable medical temperature sensors. Our disposable medical temperature sensors have a standard temperature measurement range from -40°C to +80°C with an accuracy of ±0.1°C from +25°C to +50°C. The outer diameter of the temperature probe is generally 0.78mm to 1.78mm - the smallest can be 0.48mm, which makes it suitable for the treatment of both adults and children. A wide range of lead lengths and wire insulation types can be provided according to customer requirements. Temperature accuracy for assemblies can also be customized to meet specific customer requirements.

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Like the NTC thermistor, the thermocouple sensor is light-weight and competitively priced.  A thermocouple sensor consists of two dissimilar metals, joined together at one end in a thermcouple junction. When the thermocouple junction is at a different temperature than the other end of the wires a millivolt signal is generated this junction is where the temperature is measured. A small voltage is produced by the two metals, which can be measured and interpreted by a control system. The dissimilar metals are individually insulated, and an overcoat is present to maintain an intimate bifilar configuration.

A thermocouple will only indicate what the temperature difference is between the hot and the cold end, therefore another sensor is required, typically an NTC, to measure the temperature at the metering side. This is called cold junction compensation. The strength of thermocouples lies in the very wide temperature range that they are capable of handling.

 

Class 1 thermocouples are built according to IEC584. Custom thermocouple solutions are available. Commercial thermocouples are inexpensive, interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures to +1700°C. In contrast to most other methods of temperature measurement, thermocouples are self-powered and require no external form of excitation. The main limitation with thermocouples is precision; system errors of less than one degree Celsius (°C) can be difficult to achieve.

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thermocouples

Applications

Applications for thermocouples include everything from industrial process control to commercial ovens and heaters, home appliances to jet engine exhaust gas temperature and even some special medical applications.

 

Medical applications such as catheters require extremely small temperature sensors to ensure a rapid response to changes in temperature. Beyond a fast time response, these applications also require accurate and reliable sensors that are rugged enough to withstand the rigors of the medical operating environment. We design and manufacture a variety of micro-thermocouple sensors in both type K and type T, sizes down to AWG#44, both welded and soldered and several different insulations. These micro-thermocouples provide an option to thermistor assemblies for very small catheter assemblies.

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RTD stands for resistance temperature detector.  While an NTC thermistor is also a resistance device, an RTD is reserved for positive temperature coefficient metal resistance detectors. Typically, RTDs are manufactured with base metals such as platinum, nickel, or copper as these materials have a positive temperature coefficient that is very linear and repeatable. Typical operating temperature range is from -50°C to +600°C but special designs allow usage from -200°C to +1000°C. 

Platinum temperature sensor
platinum temperature sensors

We manufacture RTD probes and assemblies, and RTD sensor elements, both platinum thin film as well as glass wire-wound. Platinum (Pt) is the most common material used for RTDs as it has the most stable resistance–temperature relationship over the largest temperature range. To provide interchangeability between manufacturers for the sake of global industry, there are some international standards that have been adopted by most countries including DIN EN 60751 which defines the temperature accuracy and the resistance/temperature characteristic curve for several tolerance classes.

 

Our RTD platinum thin film elements provide high accuracy and stability, with a wide selection of standard sizes, accuracy classes and are available in both Pt100 and Pt1000 base resistance values to meet the growing industry demand for accurate, stable and reliable platinum sensor elements.

Applications

The applications for RTD sensors are extremely broad, including medical, aerospace, automotive, instrumentation, appliances, motor control and HVACR. One expanding application for platinum sensor assemblies is for exhaust gas temperature (EGT) measurement. An EGT sensor measures the temperature of the engine exhaust gas to prevent damage to critical components such as the after-treatment system, turbines and cylinder head exhaust valves. An EGT can help optimize engine performance and deliver savings in fuel and maintenance costs.

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Thermopiles are designed to be non-contact temperature sensors and are able to measure the temperature of an object or surface from a distance.  Thermopiles can also be used for gas concentration measurement such as CO2 and other gasses. The thermopile sensors are all packaged in a TO-5 or TO-18 hermetic can that includes a reference temperature sensor. The modules combine the sensing element with electronics to provide a device with digital output for easy interface to measurement systems. The TSD series of digital thermopile system  combines an infrared sensor and a sensor signal conditioning ASIC in a compact TO5 package. The TSD digital thermopile is factory calibrated with an I2C interface, low power consumption and a ±1°C standard accuracy.

thermopile
digital thermopile sensors

Applications

Thermopiles have been used in a broad range of applications ranging from industrial process monitoring, occupancy and motion sensing to home appliances such as microwave ovens, fire and heat alarms, automotive seat occupancy and road and highway ice detection. Thermopiles can also be used to measure body temperature remotely and the ability to accurately determine body temperature safely and remotely has become very important. Thermopiles are used in a variety of temperature scanning devices for airports, offices, schools and anywhere else where screenings are needed. Our enhanced portfolio of analog and digital thermopile elements help address this need.

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Digital temperature sensors can convert temperature physical quantity and humidity quantity into a digital sensor through a temperature and corresponding circuit. TE Connectivity designs and manufactures three different series of digital temperature sensors that provide industry leading accuracy of ±0.1°C. The Temperature System Sensors (TSYS) are available in miniature packages designed specifically for tight spaces and respond quickly to changes in process temperature. The optimized microcircuit design allows fast conversion times along with very low power consumption and operation time from -40°C to +125°C.

Digital temperature sensors are commonly used in thermostats and as board mounted sensors in many electronic devices such as home appliances, medical devices and consumer electronics and smart home applications. The TSYS03 is a full-digital temperature sensor in a miniature TDFN8 package with dimensions of 2.5 x 2.5 x 0.75mm or an even smaller XDFN6 package with dimensions of 1.5 x 1.5 x 0.38 mm. The TSYS03 is factory calibrated with 16-bits of resolution, a programmable I2C address and an accuracy of ±0.5°C. The small size of this digital temperature sensor enables a faster thermal response time which translates into faster temperature readings. The TSYS03, with its improved ASIC design and reduced package size enables exceptional price-to-performance ratio. We also manufacture a range of combination humidity-temperature sensing products including the recently released HTU31 with ±2% accuracy for humidity and ±0.2°C accuracy for temperature.

digital temperature sensors
digital temperature sensors

Applications

Digital temperature sensors are commonly used in thermostats and as board mounted sensors in many electronic devices such as home appliances, medical devices and consumer electronics. Digital temperature sensors are used in all IoT systems, like smart home applications. The digital temperature sensor can trigger home heating or air-conditioning systems, helping to maintain a comfortable home temperature and optimizing energy consumption.

Comparison of NTC thermistor, thermocouple, platinum temperature (RTD), thermopile and digital temperature sensors.

Summary

Temperature sensors are one of the most widely applied technological devices in the world – helping people in many unique ways. Whether you are sipping your coffee while reading newspaper in your home, or navigating your car through the city to get to your office or even simply sitting in your office comfortably enjoying the “right” temperature as you type through your daily work, you may not always notice them in your life because they secretly monitor all temperature around you to ensure everything will function properly with appropriate temperature range, but you would certainly notice them if they were gone! TE Connectivity is proud to be a part of this story, and to offer a wide range of temperature sensor products to meet your needs.