Page 58
ST 800 Series HART/DE Option User’s Manual
Revision 5.0
7.
Select
Yes
, and note the output current at 0%, 100% or the other value established in the
previous step. With the Transmitter in analog mode, you can observe the output on an
externally connected meter or on a display. In DE mode, the output can be observed on the
display or on the monitor display of the MC Toolkit.
8.
To view the Monitor display, navigate back from the LOOP
TEST display, and select the
MONITOR display. A confirmation prompt will be displayed for you to verify that you want
to change pages. Select
Yes
.
6.5 Calibrating Range Using the MC Toolkit
The range calibration involves two procedures, one to calibrate the input, the other to calibrate the
output. This section provides both procedures.
6.6 Conditions for Input Calibration
Calibrate Transmitter input only when necessary, and under conditions that will ensure accuracy:
•
Take Transmitter out of service, and move it to an area with favorable environmental conditions, for
example, clean, dry, and temperature-controlled
•
The source for the input pressure must be precise, and certified for correct operation.
•
Qualified personnel are required for the input calibration procedure.
To optimize accuracy, the PROM includes storage for calibration constants: Correct Input Zero,
Correct LRV, and Correct URV. These constants provide for optimum accuracy in that they enable
fine-tuning of the input calculations by first correcting at zero input, then by bounding the input
calculations at the selected operating range. Corrections are applied at the Lower Range Value (LRV)
and the Upper Range Value (URV).
Factory calibration can be specified when you order your Transmitter. Also, if precision equipment,
suitable environment, and required skill are available at your site, input calibration can be done
locally.
The input calibration procedure in this section comprises the steps for calibrating a differential
pressure (DP) Transmitter to a range of 0 to 200 in H2O for example purposes. This procedure
assumes that the Transmitter is removed from the process and located in a controlled environment.
The procedure needs a precision pressure source with an accuracy of 0.04% or better to do a range
calibration. Factory calibration of the ST 800 Pressure Transmitter is accomplished with inches-of-
water ranges referenced to a temperature of 39.2 °F (4°C).
6.7 Input Calibration Procedures Description
The input calibration process consists of the following three parts:
•
Correcting the input at zero pressure.
•
Correcting the input LRV.
•
Correcting the input URV.
