Campbell Scientific AVW1 and AVW4 Interfaces for Vibrating Wire Sensors User Manual
Page 18
AVW1/AVW4
4-2
water. The water depth above the sensor is
referred to as the "Reading" in the following
equation. The Reading decreases with
increasing "Distance" from lip of well to water
surface so the Distance is computed by
subtracting the Reading from the Offset as
shown in the above figure and the following
equation.
Distance = Offset - Reading
FIGURE 4.3-1. Well Monitoring Example
The "Initial Distance" to the water surface is
measured with a chalked line to be 47.23 feet
below the lip. The "Initial Reading" is 54.832
feet (of head above the sensor). Solving the
above equation for the Offset, one obtains:
Offset = Initial Distance + Initial Reading
= 47.23 feet + 54.832 feet
= 102.062 feet
The following is a sample program that
measures the temperature and frequency of the
vibrating wire sensor and stores the
temperature (
o
C), pressure (psi), temperature
corrected pressure (psi), correction factor (psi),
temperature corrected pressure (feet of H2O),
and Distance from the lip to the water surface
(feet) in Input Locations 1-6 respectively. This
example assumes the sensor has been
connected as shown in Figure 4.2-1.
Program: AVW & CR10 USED TO MEASURE
1 GEOKON VIBRATING WIRE SENSOR.
*
1
Table 1 Programs
01:
10
Sec. Execution Interval
01:
P4
Excite,Delay,Volt(SE)
01:
1
Rep
02:
15
2500 mV fast Range
03:
1
IN Chan
04:
1
Excite all reps w/EXchan 1
05:
1
Delay (units .01sec)
06: 2500
mV Excitation
07:
1
Loc [:TEMP C]
08:
.001
Mult
09:
0.0000
Offset
02:
P55
Polynomial
01:
1
Rep
02:
1
X Loc TEMP C
03:
1
F(X) Loc [:TEMP C]
04:
-104.78
C0
05:
378.11
C1
06:
-611.59
C2
07:
544.27
C3
08:
-240.91
C4
09:
43.089
C5