SCC-RTD01 lead compensation

[Humph]

I'm a programmer, not an engineer. I know that you have to switch electrical sockets off if there is no plug inserted or the electricity will dribble out.

My engineers tell me that the 3 wire Platinum Resistance Thermometer we have attached to the SCC-RTD01 module on an SCC-68 board works fine when the RTD is attached directly to the module, but the temperatures are wrong when the RTD is attached at the end of a long (30 metres) umbilical cable. They say that the RTD01 is not compensating correctly for the long lead. They say that the wiring diagram in the RTD01 manual will ADD the compensating value instead of subtracting. Has anyone else experienced any problems?

[Humph]

I should have said that this is a 3-wire RTD, and the connection is as per the 3-wire option in the RTD01 manual.

[AnalogKid2DigitalMan]

2 and 3 wire configurations are susceptible to long lead lengths, 4 wire is immune. A 3 wire remote sense configuration may improve the situation.

Is it an electrically 'noisy' environment? That may also introduce errors.

-AK2DM

[Henrik_Volkers]

For 30m it's worth to take a look at the cable. If it has 4 wires / two pairs it would be best to switch to a 4 wire measuremt.  Even if your sensor is only a three wire, if you keep the 'three wire zone' as short as possible, the error might be less. 

(Depending on your application..)

For your question about the wrong compensation , sorry no experience (I always took the 4 lane road ;-).

Ask your engineers for three 1 an 10 -Ohm resistors, add them to the cable and take a look ....