Endress+Hauser FMX 570, Руководство по эксплуатации

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Offset and sensitivity of
the display, V3H1/V3H2 The entry of values in V3H5/V3H6 adapts
the Silometer to the application. It now
knows which pressure is associated with a
particular frequency. The next step is to
adapt the display, i.e. the measuring range
is fixed. This requires the entry of:
•
the offset in mbar in V3H1
The offset is the pressure in mbar
which acts on the sensor when the
display reads »0«, i.e.
V3H1 = p
zero
•
the sensitivity in mbar/digit in V3H2
The sensitivity determines the change
in the measured value
∆
h in V0H0 per
mbar change at the sensor, i.e.
V3H2 =
∆
p/
∆
h = (p
2
- p
1
)/(h
2
- h
1
)
•
the pressures: p
mbar
= 10 x
ρ
(kg/dm
3
) x g (m/s
2
) x
∆
h (m)
Example 1: Example: For 0.45 m water display = 0%, for 10 m water, display = 100%
•
Maximum display = 100%
•
Determine pressures
p
zero
= 10 x 1.0 x 9.807 x 0.45 = 44.13 mbar
p
100%
= 19 x 1.0 x 9.807 x 10 = 980.7
•
Sensitivity =
∆
p/
∆
h
= (980.7 - 44.13)/(100 - 0) = 936.6/100 = 9.366 mbar/%
•
Offset, V3H1 = 44.13 mbar
Sensitivity, V3H2 = 9.366 mbar/%
Example 2: Example: For 0.45 m water display = 50 hl, for 10 m water, display = 2000 hl
•
Maximum display = 2000 hl
•
Determine pressures
p
50 hl
= 10 x 1.0 x 9.807 x 0.45 = 44.13 mbar
p
2000 hl
= 19 x 1.0 x 9.807 x 10 = 980.7
•
Sensitivity =
∆
p/
∆
h
= (980.7 - 44.13)/(2000 - 50) = 936.6/1950 = 0.4803 mbar/hl
•
Since 50 hl is displayed for 0.45 m water,
p
zero
has to be calculated
p
zero
= p
50 hl
- h1 x sensitivity
= 44.14 - 50 x 0.4803 = 44.13 - 24.01 = 20.12
•
Offset, V3H1 = 20.12 mbar
Sensitivity, V3H2 = 0.480 mbar/hl
»Dry calibration«,
Sensor adjustment
Step Matrix Entry Significance
1 V3H1 e.g. 20.12 Enter offset (V0H0 displays 50 for 45 cm water)
2 - »E« Register entry
3 V3H2 e.g. 0.480 Enter sensitivity
4 - »E« Register entry
5 V0H0 The measured value is displayed in the units selected
Probe sensitivity
∆
F,
V3H6
P/mbar
level
m
easur
em
ent
span
d
isp
la
y sp
an
Offset
V3H1
Zero frequency
f/Hz
BA119E62
Fig. 4.4:
Parameters for dry calibration with Deltapilot probe
Chapter 4: Calibration and Operation Silometer FMX 570
21