rosemount 3144 Temp transmitter question 1

[tslman]

I have a 3144P, 0-150deg F, 4-20ma output. Using a test device to simulate RTD input to the transmitter, I have 0F and 4ma output and at 150F i have 20ma output and it is read correctly on my PLC. This is all good, the problem lies with this, when I put a calibrated temp probe in the thermowell next to the transmitter to verify the temp my test probe reads 1.2 degrees more than the transmitter. I need to calibrate the transmitter or adjust the transmitter to read the correct temperature as the test probe, within .5 degrees. I have not done this in a while so am rusty at this, need a refresher. Is the RTD bad?
Thanks.

 

[danw2]

The Sensor Trim command allows the user to digitally alter the transmitter’s interpretation of the input signal as shown in Figure 3-6 on page 3-28. The sensor trim command trims, in engineering (°F, °C, °R, K) or raw (?, mV)units, the combined sensor and transmitter system to a site standard using a
known temperature source.

pg 60, Rosemount 3144P Temperature Transmitter manual

http://www2.emersonprocess.com/siteadmincenter/PM Rosemount Documents/00809-0100-4021.pdf

Navigation sensor trim is 1 > 2 > 2 > 1 > 1 according to the menu structure:

 

[roydm]

As I said on the other site you posted make sure that one of your RTDs is not a different curve.

 

[tslman]

Thanks, I can't find the other site I posted on. Out of town now so will try it out when I get back. The process is out of service right now so I have time. Thanks

 

[KiwiMace]

Sensor trim. Nice. It somehow seems to legitimise the old instrument tech response: OK, What do you want it to read?

If the rtd is the right animal (and such a small difference suggests it is) you should consider what is different between the reference instrument and this transmitter: length/diameter of t-well vs length/diameter of probe, use of heat paste and then put both of them in ice water and boiling water and use this reference to calibrate the sensor. RTD's usually read very accurately or not at all. I would be looking for installation issues here.

 

[tslman]

Another question, the manual speaks of upper and lower trim, does this mean 0 and 150f. Getting confused again. So do I have to do what the previous post says too? Basically I want to know how to make it read the same as the test probe, in simple terms.