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• Resistance temperature detectors, or RTDs, change the resistance of the RTD element directly with temperature.
• RTDs are made from a film and a glass or ceramic core with wire wrapped around it for greater accuracy.
• Platinum RTDs are available with a 100 Ω and 1000 Ω resistance at 0 °C, which is why they are referred to as PT100 and PT1000.
• Platinum RTDs offer a highly accurate linear output?across -200 to 600 °C but are much more expensive than copper or nickel.

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• When the temperature of a metal increases, the resistance to the flow of electricity increases as well.
• An electrical current is passed through the sensor, the resistance element is used to measure the resistance of the current being passed through it.
• As the temperature of the resistance element increases the electrical resistance also increases.
• The response time for an RTD is between 0.5 and 5 seconds.