Geokon 4430, Инструкция по эксплуатации, Страница: 17 / 24

11
4. DATA REDUCTION
4.1 Deformation Calculation
The basic units utilized by Geokon for measurement and reduction of data from Vibrating Wire
Deformation Meters are "digits". The units displayed by all Readout Boxes in position "B" are
digits. Calculation of digits is based on the following equation:
Digits =
�
1
Period
�
2
x 10
-3
or Digits
=
Hz
2
1000
Equation 1 - Digits Calculation
To convert digits to deformation the following equation applies:
Deformation = (Current Reading - Initial Reading) × Calibration Factor × Conversion Factor
Or
D = (R
1
- R
0
) × G × F
Equation 2 - Deformation Calculation
Where;
R
1
is the Current Reading.
R
0
is the Initial Reading usually obtained at installation (see Section 2.5).
G is the Calibration Factor, usually in terms of millimeters or inches per digit.
F is an engineering units conversion factor (optional), see Table 1.
From →
To ↓
Inches Feet Millimeters Centimeter
s
Meters
Inches 1 12 0.03937 0.3937 39.37
Feet 0.0833 1 0.003281 0.03281 3.281
Millimeters 25.4 304.8 1 10 1000
Centimeters 2.54 30.48 0.10 1 100
Meters 0.0254 0.3048 0.001 0.01 1
Table 1 - Engineering Units Conversion Multipliers
For example, taken from the typical Calibration Sheet shown in Figure 10, the Initial Reading
(R
0
) at installation of a deformation meter with a 25 mm transducer range is 4250 digits. The
Current Reading (R
1
) is 6785. The Calibration Factor is 0.004457 mm/digit. The deformation
change is:
D = (6785
−
4250)
×
0.004457 = +11.4 mm
Note that increasing readings (digits) indicate increasing extension.