Hi Control.com experts....
Recently i am working on a data sheet for the selection of temperature transmitter (PT100, 3Wire RTD). My process data range is 0 deg to 200deg. Now i have to select the required range limit and calibration range of the transmitter. How can i select those parameter and is there any standard for selection based on process data?
Temperature transmitters are mostly universal and flexible enough to incorporate all type of sensors (TC/RTD etc.) and can easily be programmed to give current output in desired temperature range.
You only need to decide which kind of physical installation you prefer.
You may chose field mounted or head mounted temperature transmitters which convert the signal to mA in field an can be transmitted to control system using ordinary two-wire cable.
If your RTD cable is already laid between sensor and control cabinet, then you may chose a rail mount converter which will be installed in the system cabinet.
See the following link for details.
Field mount transmitter is perhaps the most expensive, but it gives you an added advantage of a local reading as well, if needed.
Besides Yokogawa, P+F also has rail mounted solutions for temperature conversion. See the following.
The above unit requires a software and a special programming cable for configuration, if you want to avoid it, use the following.
This unit has more functions and has a programming keyboard which is easy to use and configure.
Most RTD temperature transmitters can be programmed for a specific temperature range within the total temperature range for that RTD type. For a Pt100 RTD, the overall temperature range is -200 deg C to +850 deg C. Once you set the transmitter up for a Pt100 RTD, you can then program a temperature range to correspond to you minimum and maximum output signal range (i.e. 4-20mA, 0-10V, etc.). The input signal is usually linearized so that the output signal will be linear with respect to the input temperature. We offer several RTD temperature transmitters that will accomplish this function.
Kevin M. Dziadzio
Applications Engineer - Process Products Sales Group
30765 S Wixom RD, Wixom, MI 48393-7037 USA
If your question is what should the transmitter range be given that the process range is 0-200°C, allow for high end margin, like 0-250 or 0-300, given that most processes don't run near 0°C, but someone very likely will want to see overshoot or over temperature conditions.
Round numbers are nice because the scale on the historian can have even sub-divisions.