Transmitter square-root range issue
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This post was last edited by f7252966 on 2017-12-1 01:56. Is the range of the DCS after taking the square root of the value equal to the range obtained after taking the square root in the control room? Example: A transmitter has a range of 0-20t; if the output of the square-root transmitter in the DCS is 10.4mA, then the DCS range is also 0-20t, right? After taking the square root of the value displayed on the meter, does the transmitter output a DC current of 6.56 mA within the 0-20 mA range, or is it in the 0-20 t range? Thank you all, please let me know
If the transmitter can have its range set in flow units, does that mean the signal output by this meter is the flow value after taking the square root? In that case, the DCS wouldn’t need to take another square root. Taking the square root refers to converting the flow rate after taking the square root of the differential pressure.
The range of the DCS should be consistent with that of the transmitter, and it does not matter whether it is the transmitter’s value that is squared or the DCS’s value.
For differential pressure flow transmitters, the signals need to be squared; the transmitter is set to the differential pressure value at zero flow and full flow, while the DCS defines a range corresponding to the flow rate.
Did you set your transmitter directly to 0-20t? Would that mean the squaring is done directly inside the transmitter, in which case setting the range to 0-20 in the DCS would be sufficient! If the transmitter displays the differential pressure, then either the transmitter needs to perform a square root operation or the DCS needs to do so!
The original poster should communicate with everyone; that would make it easier to explain.
The measurement ranges on both sides are the same; the DCS does not require taking a square root when dealing with the gauge reading, and only one square root operation is needed for either the gauge or the DCS. The range needs to be set the same way
Generally, it is DCS that is used for access, as it is convenient; the transmitters still need to be taken to the site