FW_F126PEGTP_v1901_04_EN.docx
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3.1.8.
EXPLANATION OF SETUP MENU 7 - PRESSURE
MEASURING UNIT
71
This setting is used to program the temperature unit which is shown to the
operator. This setting does not influence the actual calculations.
SPAN
72
With this setting, the measurement range of the (0)4-20mA pressure
sensor is determined according the selected measurement unit.
Example
Calculating the span for pressure.
The sensor generates the minimum signal (e.g.4mA) at a pressure of 2.5
bar and the maximum signal (e.g. 20mA) is generated at 50 bar. Then the
span is 47.5 bar. Enter for
Span
: "0004750" if decimals for span are two.
DECIMALS SPAN
73
This setting is used to set the amount of digits behind the decimal point for the
pressure span.
OFFSET
74
Calculations are based on absolute pressures.
The flow computer must know the measured pressure at minimum signal.
(2.5 bar in above example)
•
When using a gauge type pressure indicator enter an offset to
compensate environmental pressure (e.g. air pressure, 1.013 bar)
•
When working with a “fixed” pressure, enter the fixed line pressure here
and make sure that the span is set to zero.
FILTER
75
This setting is used to stabilize the flow rate reading. With the help of this
digital filter a more stable but less actual reading can be obtained. The
filter principal is based on three input values: the filter level (01-99), the
last calculated flow rate and the last average value. The higher the filter
level, the longer the response time on a value change will be. In practice it
is best to use trial and error to find the best setting for your application.
F
ILTER VALUE
R
ESPONSE TIME ON STEP CHANGE OF ANALOG VALUE
.
T
IME IN SECONDS
influence
50%
75%
90%
99%
01
filter disabled
filter disabled
filter disabled
filter disabled
03
0.5 sec
1.0 sec
1.5 sec
3 sec
05
1.0 sec
1.8 sec
2.8 sec
5.3 sec
10
1.8 sec
3.5 sec
5.6 sec
11 sec
20
3.5 sec
7.0 sec
11 sec
23 sec
50
8.8 sec
17 sec
29 sec
57 sec
99
17 sec
34 sec
57 sec
114 sec
CALIBRATE LOW
76
This setting is used to calibrate the input value for (0)4mA as the signal
from the flowmeter might not be exact 4.0 mA (or 0.0 mA) at flow rate
zero. This function will measure the real output value at flow zero.
Be very sure that the offered signal is correct before the calibration
is executed as this function has major influences on the accuracy of
the system!
After pressing PROG, three settings can be selected:
▪
CALIB: with this setting, the input will be calibrated with the actual
"(0)4mA" value. After pressing enter, CAL SET will be displayed as
soon as the calibration is completed. From that moment, the analog
value must be more than the calibrated value before the signal will be
processed.
▪
DEFAULT: with this setting, the manufactures value is re-installed.
▪
CAL SET: to select the last calibrated value.
CALIBRATE HIGH
77
This setting is used to calibrate the input value for 20mA as the signal
from the flowmeter might not be exact 20.0 mA at maximum flow rate.
This function will measure the real output value at maximum flow rate.
Be very sure that the offered signal is correct before the calibration
is executed as this function has major influences on the accuracy of
the system!
After pressing PROG, three settings can be selected:
▪
CALIB: with this setting, the input will be calibrated with the actual
"20mA" value. After pressing enter, CAL SET will be displayed as
soon as the calibration is completed. From that moment, the analog
value must be less than the calibrated value for a reliable
measurement.
▪
DEFAULT: with this setting, the manufactures value is re-installed.
▪
CAL SET: to select the last calibrated value.
