69
10 Supplement
VEGABAR 87 • Modbus and Levelmaster protocol
46297-EN-220624
Turn Down
TD 1 : 1
TD 2.5 : 1
TD 5 : 1
TD 10 : 1
TD 20 : 1
Factor FTD
1
1.75
3
5.5
10.5
Tab. 47: Determination of the additional factor "turn down" for the above example: F
TD
= 1.75
Turn Down
TD 1 : 1
TD 2.5 : 1
TD 5 : 1
TD 10 : 1
TD 20 : 1
Factor FTD
1
1.75
3
5.5
10.5
Tab. 48: Determination of the additional factor "turn down" for the above example: F
TD
= 1.75
F
T
= F
TBasis
x F
MZ
x F
TD
F
T
= 0.15 % x 1 x 1.75
F
T
= 0.26 %
3. Determination of deviation and long-term stability
The required values for deviation F
Kl
and long-term stability F
stab
are available in the technical data:
Accuracy class
Non-linearity, hysteresis and non-repeatability
TD ≤ 5 : 1
TD > 5 : 1
0.1 %
< 0.1 %
< 0.02 % x TD
Tab. 49: Determination of the deviation from table: F
Kl
= 0.1 %
VEGABAR 86
Time pe-
riod
Measuring cell ø 28 mm
Measuring cell
ø 17.5 mm
All measuring ranges
Measuring range
0 … +0.025 bar/0 … +2.5 kPa
One year
< 0.05 % x TD
< 0.1 % x TD
< 0.1 % x TD
Five years
< 0.1 % x TD
< 0.2 % x TD
< 0.2 % x TD
Ten years
< 0.2 % x TD
< 0.4 % x TD
< 0.4 % x TD
VEGABAR 87
Time period
All measuring ranges
Measuring range
0 … +0.025 bar/0 … +2.5 kPa
One year
< 0.05 % x TD
< 0.1 % x TD
Five years
< 0.1 % x TD
< 0.2 % x TD
Ten years
< 0.2 % x TD
< 0.4 % x TD
Tab. 50: Determination of the long-term stability from the table, consideration for one year: F
stab
= 0.05 % x TD =
0.05 % x 2.6 = 0.13 %
4. Calculation of the total deviation - digital signal
- 1. step: Basic accuracy F
perf
F
perf
= √((F
T
)
2
+ (F
Kl
)
2
)
F
T
= 0.26 %
F
Kl
= 0.1 %
