Temperature transmitter calculations
Our temperature transmitter has an input range of 0 to 100 degrees Celsius, an output range of 4-20 milliamps, and accuracy of ±0.5 percent. If the output of the transmitter is 13.6, what are the ideal minimum and maximum temperatures? I calculated between 67.5 and 68.5. Am I right?.
Expert’s answer: Temperature transmitter calculations
Nice try, but the resolution is simpler than your answer. So let’s organize and give you a clear step by step to make sense of your temperature transmitter calculations. First, we’ll start with your specs.
Transmitter range: 0 – 100°C
Output range: 4-20 mA
Now the output is 13.6 mA, and you want the process values, right? So here we go.
- PV – LRV / SPAN = mA – LRV/SPAN
- PV – 0/100 = 13.6 – 4/16
Still with me? Good! Let’s keep breaking it down.
- PV – 0/100 = 0.6
- PV – 0 = 0.6 x 100
And finally, PV = 60°C!
- LRV = Low range value
- SPAN = Device range from minimum to maximum
- PV = Process value
So based on the 60 degrees Celsius, you can consider the accuracy ±0.5 percent. Keep in mind that to calculate accuracy you have to consider a lot of details, such as the resolution, sensitivity, gain error, linearity error, and more. Hope that helps!
Want more information on temperature transmitter calculations
To find out more, have a peek at the links below:
Other resources that might interest you
Multipoint temperature measurement
We’re working on a project to measure 36 temperature points, but we only have 5 HART inputs in our PLC. We’d like multipoint measurement if we can get it. Do you have any suggestions?
One temperature sensor and two transmitters!
Can we connect two temperature transducers to one RTD? We need to maintain the temperature gauge and somehow place a transducer device to get a 4-20 mA output. Do we need to disable the existing gauge and replace it with a temperature gauge with this output?
Rosemount 3144P temperature transmitter
I have a Rosemount 3144P with a range of 0 to 150 degrees Fahrenheit. I was using a test device to simulate RTD input to the transmitter, where on 0 degrees Fahrenheit I have 4 mA and on 150 I have 20. Do I need to calibrate or adjust the transmitter to read the same temperature as the probe? Is the RTD bad?