VEGA VEGABAR 52 Profibus PA - climate compensated - Manual (Page 43)

43
8 Maintenance and fault rectification
VEGABAR 52 • Profibus PA - climate compensated
36788-EN-130321
8.3 Calculation of total deviation (according to
DIN 16086)
The total deviation F
total
according to DIN 16086 is the sum of basic
accuracy F
perf
and longterm stability F
stab
. F
total
is also called maximum
practical deviation or utility error.
F
total
= F
perf
+ F
stab
F
perf
= √((F
T
) 2 + (F
Kl
) 2 )
With:
•
F
total
: Total deviation
•
F
perf
: Basic accuracy
•
F
stab
: Long-term drift
•
F
T
: Temperature coefficient (influence of medium or ambient
temperature)
•
F
Kl
: Deviation
Example
Pressure measurement in the pipeline 8 bar (800 KPa)
Ambient temperature 40 °C, product temperature 10 °C, hence within
the compensated range
VEGABAR 52 climate compensated, with measuring range 10 bar
Calculation of the set Turn Down: TD = 25 bar/8 bar, TD = 1.25
Basic accuracy digital output signal in percent:
F
perf
= √((F
T
) 2 + (F
Kl
) 2 )
F
T
= (0.05 + 0.1 x TD)%
F
Kl
= 0.25 %
F
perf
= √((0.05 + 0.1 x 1.25)%) 2 + (0.25 %) 2 )%
F
perf
= 0.31 %
Total deviation digital output signal in percent:
F
total
= F
perf
+ F
stab
F
stab
= (0.1 % x TD)/year
F
stab
= (0.1 % x 1.25)/year
F
stab
= 0.125 %
F
total
= 0.31 % + 0.125 % = 0.43 %
Total deviation digital output signal absolute:
F
total
= 0.43 % x 8 bar/100 % = 34.4 mbar
8.4 Exchanging the electronics module
In case of a defect, the electronics module can be exchanged by the
user against an identical type. If no electronics module is available on
side, the module can be ordered from the agency serving you.
Ordering and exchange are possible with or without sensor serial
number. The electronics module with serial number includes order-
specific data such as factory setting, seal material etc. These are not
included in the electronics module without serial number.
Total deviation