A PT 100 sensor is a temperature sensor which works by measuring electrical resistance through platinum (Pt) metal. A PT 100 sensor can measure temperatures up to 600 °C
The resistance in the metal increases as temperature rises. The resistance at 0°C is 100 ohms – hence the name PT 100. PT 500 and PT 1000 sensors with corresponding resistance at 0°C are also available.
Therefore, the PT 100 sensor can also be used for reading temperature.
The sensor measures more precisely than other types of electrical-resistance sensors such as KTY and NTC, which use other metals, but is also more expensive. A PT 100 sensor can measure temperatures up to 600°C, where the others are limited to around 150°C.
Sensors that are connected with longer cable lengths may give imprecise readings, due to the cable’s inherent electrical resistance. This can be compensated for through the use of three-wire sensors, where the third wire measures resistance in the cable. However, this requires a regulator that can handle it.