The scale for measuring temperatures
Resistance thermometers with a Pt100 sensor are very important in temperature measurement. The sensors made with platinum change their degree of resistance according to the temperature. The resistances are divided up according to accuracy into the classes A, B and AA, as per IEC 60751:2008.
A distinction is also made as to whether a single or double Pt100 is needed. With a double Pt100, two measuring resistors are installed next to each other in a single thermometer. This arrangement is needed if two signals are being processed. The signal from the first Pt100 measuring resistor is used for the control, for example, and the signal from the second Pt100 is used for the display device.
Many different designs, depending on the area of application
Of note here are the Pt100 screw-in resistance thermometers, which are also known as screw-in Pt100 temperature sensors. These feature a sensor consisting of a stainless steel housing equipped with a thread, making it suitable for screwing into threaded holes. This produces a fixed, defined position of the measuring point.
A further version of the Pt100 temperature sensor is the Pt100 surface resistance thermometer, also known as a Pt100 surface sensor. As the name suggests, this is designed to measure surface temperature using a Pt100.
Pt100 temperature sensors are also used as Pt100 sheathing resistance thermometers. In this instance, the Pt100 measuring resistor is installed in a mineral-insulated solution and weld-sealed at the front. A sheathing resistance thermometer can be bent along its length.
To process the output signal produced by a Pt100 thermometer, for example to connect it to a PLC, a Pt100 transducer is required. A signal of 4-20 mA is then output or, in the case of a Pt100 transducer, 0-10 V.