RTD cable length Limitation

[JatTiw]

For 3-wire RTD (has Hot, Return & Compensation) is their any max. length of RTD cable can be used. As my under standing is using compeensation max. length should not be limitation.

 

[DRWeig]

Hi JatTiw,

The third wire is used as a reference so that your temperature transmitter only reads the differential resistance (the RTD), so you are correct within reasonable boundaries. Some care must be taken in extra long circuits to avoid errors due to distributed parameters even though it's a DC circuit.

How far are you going, what size conductor, and what is the RTD's base resistance? Answer these and I'll volunteer how much potential error you may be inducing.

Old Dave

 

[JatTiw]

HI DRWeig,
Thaks for the information. I am using 8TR#16(AWG) for 800'. The controller is GE multilin relay (SR-469). Please provide me the error may be introduced for 800' length