To check the PT100, the probe must be unpluged from the installation.
If any of the following three points is not met, the probe is faulty:
- Measure with the multimeter the impedance in the probe between the wires 2 and 3, it should indicate 0 omh(R=0).
- Measure the impedance between wires 1 and 2 from the PT100, it should indicate the value from the following table(DIN43760). The values should be between 80 and 300 Ohms, depending the temperature.
- Check the isolation between the 1st wire of the probe, the case and the ground. The impedance must be infinite.
Here you can find different applications for PT100, like multiplexers, isolators, converters, thermocouples, encapsulations and simulators.