Temperature PT100

Hi Every body

The PT100 is used to measure lubracation oil temperature and it connected to DCS through intrinsically card, but this sensor gives a spikes from time to time
Any ideas why this happen

Thank you all

Elkawafi

Maybe bad connections. Normally in a 4-wire system a constant current is sent through the PT100 via one pair of wires, while the voltage generated over the resistance by that current is measured on the other pair. If one or more of the wires shows a bad contact, you end with a lower measured value.

Sometimes a 2-wire PT100 is connected to a 4-wire system. It means you'll have to connect a current source wire and a measuring wire to each end of the PT100. If one of the connections has a high resistance (bad contact) then this could result in a measured value which is higher than expected.

Kind regards,

Is the cable screened and grounded at only 1 end? If not it should be.