Vega VEGABAR 86 Operating Instructions Manual page 63

Accuracy class
0.1 %
Tab. 24: Determination of the deviation from table: F
VEGABAR 86
Time pe-
riod
All measuring ranges
One year < 0.05 % x TD
Five years < 0.1 % x TD
Ten years < 0.2 % x TD
VEGABAR 87
Time period
One year
Five years
Ten years
Tab. 25: Determination of the long-term stability from the table, consideration for one year: F
0.05 % x 2.6 = 0.13 %
4. Calculation of the total deviation - 4 ... 20 mA signal
- 1. step: Basic accuracy F
F = √((F ) + (F )
2 2
perf T Kl
F = 0.26 %
T
F = 0.2 %
Kl
F = 0.15 %
a
F = √(0.26 %) ) + (0.1 %)
2 2
perf
F = 0.32 %
perf
- 2. step: Total deviation F
F = F + F
total perf stab
F = (0.05 % x TD)
stab
F = (0.05 % x 2.5)
stab
F = 0.13 %
stab
F = 0.32 % + 0.13 % = 0.45 %
total
The total deviation of the measuring system is hence 0.45 %.
Deviation in mm: 0.45 % of 1600 mm = 7 mm
The example shows that the measurement error in practice can be considerably higher than the
basic accuracy. Reasons are temperature influence and Turn down.
VEGABAR 86 • 4 ... 20 mA
TD ≤ 5 : 1
< 0.1 %
Measuring cell ø 28 mm
Measuring range
0 ... +0.025 bar/0 ... +2.5 kPa
< 0.1 % x TD
< 0.2 % x TD
< 0.4 % x TD
All measuring ranges
< 0.05 % x TD
< 0.1 % x TD
< 0.2 % x TD
perf
+ (F ) )
2
a
) + (0.15 %)
2 2
total
Non-linearity, hysteresis and non-repeatability
= 0.1 %
Kl
)
11 Supplement
TD > 5 : 1
< 0.02 % x TD
Measuring cell
ø 17.5 mm
< 0.1 % x TD
< 0.2 % x TD
< 0.4 % x TD
Measuring range
0 ... +0.025 bar/0 ... +2.5 kPa
< 0.1 % x TD
< 0.2 % x TD
< 0.4 % x TD
0.05 % x TD =
stab
63