Calculation Of Total Deviation (According To Din 16086) - Vega VEGABAR 66 Operating Instructions Manual

8 Maintenance and fault rectification
Total deviation
Example
52
?
E113
Communication conflict
l
à Exchange the instrument or send it in for repair
8.3 Calculation of total deviation (according to
DIN 16086)
The total deviation F
total
accuracy F and longterm stability F
perf
maximum practical deviation or utility error.
= F + F
F
total perf stab
2
= √((F + (F
F ) )
perf T Kl
With the analogue signal output there is also the error of the current
output F .
a
2
= √((F + (F
F ) )
perf T Kl
With:
F : Total deviation
l
total
F : Basic accuracy
l
perf
F : Long-term drift
l
stab
F : Temperature coefficient (influence of medium or ambient
l
T
temperature)
F : Deviation
l
Kl
F : Error current output
l
a
Level measurement 1500 mmWs
Product temperature 40 °C, reference temperature 20 °C
Selected: VEGABAR 66 with measuring range 0.2 bar
Calculation ΔT: ΔT = 40 °C - 20 °C = 20 K
Calculation of the set Turn Down:
TD = 200 mbar/147 mbar, TD = 1.4
Basic accuracy digital output signal in percent:
2
= √((F + (F
F ) )
T Kl
perf
= 0.05 %/10 K x TD
F
T
= 0.1 %
F
Kl
= √((0.05 %/10 K x 20 K x 1.4)
F
perf
= 0.17 %
F
perf
Total deviation digital output signal in percent:
= F + F
F
total perf stab
= 0.1 %/year x TD
F
stab
according to DIN 16086 is the sum of basic
. F
stab
2
)
2 2
(+ F ) )
a
2
)
2
+ (0.1 %)
VEGABAR 66 • Foundation Fieldbus
is also called
total
2
)