PT100 elements come in many types conforming to different standards, capable of different temperature ranges, with various sizes and accuracies available. But they all function in the same manner: each has a pre-specified resistance value at a known temperature which changes in a predictable fashion. In this way, by measuring the resistance of the element, the temperature of the sensor can be determined from tables, calculations or instrumentation. These resistance elements are the heart of the Pt100
What is a Pt100 Temperature Detector?
Resistance Temperature Detectors (RTD), as the name implies, are sensors used to measure temperature by correlating the resistance of the Pt100 sensor with temperature. Most RTD sensors consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is usually quite fragile, so it is often placed inside a sheathed probe to protect it.
The RTD sensor is made from a pure material whose resistance at various temperatures has been documented. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.
How are the Pt100 sensors manufactured?There are two main types of Pt100 element: wire wound and thin-film.
Wire Wound Pt100 Elements
Wire wound elements consist of a length of fine Platinum wire coiled around a ceramic or glass core. These types of Pt100 sensor are typically 1 to 5mm diameter and 10 to 50mm in length. The ceramic or glass core can make them fragile and susceptible to vibration so they are normally protected inside a probe sheath for practical use.
Thin Film Pt100 sensors
Thin film Pt100 sensors are manufactured using materials and processes similar to those employed in the manufacture of integrated circuits. A platinum film is deposited onto a ceramic substrate which is then encapsulated. This method allows for the production of small, fast response, accurate sensors.
What is the Accuracy of Pt100 sensors?
The International Standard IEC 751:1983 specifies the tolerances for industrial platinum resistance thermometer sensors. There are two main tolerances defined for Pt100 probes: Class A, with a tolerance of ± 0.150°C at 0°C and Class B, with a tolerance of ± 0.3°C at 0°C. There are 2 additional accuracy classes for precision work and these are commonly referred to as "1/10 DIN" and "1/3 DIN" this means a tolerance of 1/10 or 1/3 of the Class B specification at 0°C respectively. The full Class A, B, 1/10 and 1/3 tolerances are listed in our Pt100 Accuracy Table along with details of the 2 main temperature coefficient curves available for Pt100 sensors.
Benefits of Using a Pt100
The Pt100 is one of the most accurate temperature sensors. Not only does it provide good accuracy, it also provides excellent stability and repeatability. Most OMEGA standard Pt100 comply with DIN-IEC Class A.
Pt100s are also relatively immune to electrical noise and therefore well suited for temperature measurement in industrial environments, especially around motors, generators and other high voltage equipment.