Fluidwell F053-A, Manual

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Page 15
FW-F053-A-M_v0404_01_EN.docx
3.3.6 EXPLANATION OF SETUP-MENU 5 - SENSOR
SETUP FUNCTIONS AND VARIABLES
5 SENSOR
5.1 FORMULA
The F053-A can process the (0)4-20mA signal in two ways:
▪
Interpolation: the signal is processed linear
R = S x I
▪
Square root: for differential pressure
R = S
√
I
where R = the calculated pressure, S = the maximum pressure at
20mA (span is programmed with SETUP 1.3) and I = the scaled
analog input value between 0 (zero) for (0)4mA and 1 (one) for 20mA.
5.2 FILTER
The analog output signal of a sensor mirrors the actual pressure. This
signal is measured several times per second by the F053-A. The
value measured is a "snap-shot" of the real pressure as it will be
fluctuating. With the help of this digital filter a stable and accurate
reading can be obtained. The filter level can be set to a desired value.
The filter is based on three input values: the filter level (01-99), the
last measured analog value and the last average value. The higher
the filter level, the longer the response time on a value change will be.
Below, several filter levels with response times are indicated:
Filter value Response time to step change in analog input value (seconds)
50% 75% 90% 99%
01 filter disabled filter disabled filter disabled filter disabled
02 0.3 0.5 1.0 1.8
03 0.5 1.0 1.5 3.0
05 1.0 1.8 2.8 5.3
10 1.8 3.5 5.6 11
20 3.5 7.0 11 23
30 5.3 10 17 34
50 8.8 17 29 57
75 13 26 43 86
99 17 34 57 114
5.3 CUT-OFF
To ignore pressure drift, a low-level cut-off can be set as percentage
of the full range of 16mA (or 20mA). When the analog value is less
than required with this setting, the signal will be ignored. The cut-off
value can be programmed in the range 0.0 - 99.9%. Below an
example is given.
Span
(SETUP 1.3)
Required
cut-off
Cut-off (SETUP 5.3) Required output
450 PSI 25 PSI (25/450)*100%=5.5% 16mA*5.5%+4mA=4.88mA
5.4 TUNE MIN / 4mA
With this setting it is possible to calibrate the input value for (0)4mA
as the signal from the sensor might not be exact 4.0mA (or 0.0 mA) at
pressure zero. This function will measure the real output value at
minimum pressure.
The input loop powered version - type A-PL - requires a signal of at
least 4mA; not lower!
Be very sure that the offered signal is correct before calibration is
executed, as this has major influence on the accuracy of the system
After pressing PROG, three settings can be selected:
▪
CALIBRATE: 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 factory value is re-installed.
▪
CAL SET: to select the last calibrated value.