Temperature Calibration

Hi Guys,

I need a little help in calibrating RTD Temperature transmitter, hope somebody out there will be able to help me out. It has a range of 0-300F and I want to calibrate it to 4-20ma. Once it is calibrated, I want to calculate the offset.

Could any one help me on how to do the calibration and calculate the offset.

I am using fluke 725 calibrator to do the calibration.

Thank you in advance.

What is the brand and/or model number of your transmitter?

What type of RTD do you have?

Why would you need an offset if it is calibrated properly?

You are going to need something to simulate a resistance in place of the RTD to calibrate your transmitter, a decade box is usually used.

The fluke 725 is the right instrument, use it as RTD generator. When generating 0 degrees F you must have 4 mA and when generating 300 degrees F, you must have 20 mA at the output, no offset.

in the transmitter are two potmeters so adjust together with the fluke.
check a middlepoint and it will be oke.
that is easy way.
to avoid alarmsignals you can adjust to 4.1 and 19.9 and have a scale in the PLC.

Thank you for the reply guys,

I am using RTD PT100 and the transmitter is a "Two wire programmable transmitter, PR-6333A". I understand, if I give 0F and I get 4ma and for 300F if I get 20ma, then the transmitter is OK. However, if I get different values say for example if I get 4ma for 2F and 20ma for 302F. Then what is the possible way to adjust the signal between 0 - 300 F.

What I am talking may not be right, it was just an example.

@Shooter: "in the transmitter are two potmeters so adjust together with the fluke." Could you please explain breifly.

Thank you.

Recalibrate your transmitter or subtract 2.

Abdul03 said:

Thank you for the reply guys,

However, if I get different values say for example if I get 4ma for 2F and 20ma for 302F. Then what is the possible way to adjust the signal between 0 - 300 F.

Thank you.

Click to expand...

The exact methodology depends on the transmitter. Essentially you set the Fluke to output 0 F and adjust the offset (it is probably a small screw on the transmitter) to get 4 mA. Then set the Fluke to output 300 F and adjust the span to get 20 mA. Repeat both outputs on the Fluke and readjust as required. Changing offset or span affects the other, so usually two or three iterations are necessary to get both outputs correct.