Control.com - Nerds in Control

for one of the application, we need to use dual input (rtd or thermocouple) rail mounted smart transmitter , which can take 2 nos PT100 RTD/K or T type thermocouple and after selection based on sensor healthiness/max value etc. gives out 0/4-20mA signal corresponding to the measured temperature.preferred is the programmable one, to reduce inventory.

request the control.com community to share there experience regarding use/advantages/problems faced in such measurements and the suppliers of such transmitters.

thanks in advance.

The Rosemount 3144P does what you want, I have used this on several projects. I'm sure most of the other main vendors have something similar

Regards
Roy

We use Honeywell controllers (UDC, HC-900) and recorders (SX) that have an algorithm called "thermocouple health", that somehow determines the relative health of a thermocouple. It does, in fact, detect when a thermocouple starts to drift. We've seen that in action. The result is an alarm warning when the TC is "unhealthy".

Working at high temperatures, the pollution of the TC junction and the possibility of virtual junctions has been a difficulty in temperature measurement for years.

I heard a rumor that Honeywell was considering putting that thermocouple health feature into their temperature transmitters, but I have yet to see a product.

Another appproach to drift problems is with Accutru MI insulated TCs, that use a different mineral insulating material to reduce junction pollution. We have seen a longer life from those than from conventional MgO TCs. It won't help if you're burning the sheath of jacket up, but it does reduce the tendency to drift.

Bud

You can try a product from Acromag, they have a
programmable unit that you can configure
whichever way you need. This also gives the flexibility of using 2 independent transmitters
in the field also.

Jari
iconcnl@vsnl.net