Chris Hogg wrote:
Is your application so critical that it requires precise temperature
measurement, in turn requiring that the t/cs be connected via
compensating cable rather than simple copper cable? I don't know
exactly what difference it makes, but I doubt it's more than a few
degrees, BIMBW. To be really precise, you should have a
temperature-controlled cold junction in the circuit (not a lot of
people know that).

I thought by definition you got a cold junction, whether you wanted one or
not? The trick being that you should put the cold junction compensation (ie
the thermistor, or chip with a semiconductor temperature sensor) close to
the cold junction (where you solder/crimp/whatever to the hot junction
leads) so that it is at the same temperature as the inherent cold junction.
The cold junction doesn't have to be in an ice bucket, just there be minimal
difference between the cold junction and the sensor which is used to
compensate.

The problem with a non-compensated cable is the cold junction then becomes a
long way from the compensating sensor and so there can be temperature
differential between the two. Particularly problematic if there are large
heating appliances involved.

Theo