Pt 100 sensors are the most common type of platinum resistance thermometers. A Pt 100 sensor is a temperature sensor which works by measuring electrical resistance through platinum (Pt) metal and 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.
Grundfos builds in or provides as an option Pt 100 sensors as a protection against overheating or too high temperature in pumps.