The four main types of temperature sensors are Thermocouples, RTDs (Resistance Temperature Detectors), Thermistors, and Semiconductor Sensors. Each type works on a different principle and is chosen based on accuracy, temperature range, and application. These sensors convert temperature changes into electrical signals that can be read by controllers, indicators, or PLC systems.
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Thermocouples – These are the most common and rugged temperature sensors. They work on the Seebeck effect, which generates a voltage when two dissimilar metals are joined and exposed to different temperatures. Thermocouples have a wide temperature range (–200°C to +1800°C) and are ideal for industrial furnaces, kilns, and process plants. Common types include J, K, T, and R thermocouples.
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RTDs (Resistance Temperature Detectors) – RTDs measure temperature by detecting changes in the electrical resistance of a metal, usually platinum. They offer high accuracy and stability over time, typically used in precision applications like laboratories, chemical industries, and HVAC systems. The most popular RTD is the Pt100, which has 100 ohms resistance at 0°C.
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Thermistors – These are temperature-sensitive resistors made from ceramic or polymer materials. They offer very high sensitivity within a narrow temperature range, making them perfect for medical devices, battery packs, and electronics. There are two types: NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient) thermistors.
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Semiconductor Temperature Sensors – These are integrated circuits (ICs) that provide voltage or digital output proportional to temperature. They are compact, inexpensive, and ideal for consumer electronics and low-temperature applications, typically ranging from –50°C to +150°C.
In simple terms, the 4 main temperature sensors are:
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Thermocouple – for wide range and high temperature
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RTD – for high accuracy
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Thermistor – for fast and sensitive response
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Semiconductor sensor – for compact, electronic use
Each type serves different needs depending on precision, range, and application.