Vega VEGABAR 86 Operating Instructions Manual page 56

11 Supplement
Influence of the medium or ambient temperature
Thermal change zero signal and output span through product temperature
Applies to the digital signal output (HART, Profibus PA, Foundation Fieldbus) as well as to the ana-
logue current output 4 ... 20 mA and refers to the set span. Turn down (TD) is the ratio "nominal
measuring range/set span".
The thermal change of the zero signal and output span corresponds to the value F
Calculation of the total deviation (according to DIN 16086)".
Ceramic measuring cell - Standard
Fig. 25: Basic temperature error F
The basic temperature error in % from the above graphic can increase due to the additional factors,
depending on the measuring cell version (factor FMZ) and the Turn Down (factor FTD). The ad-
ditional factors are listed in the following tables.
Additional factor through measuring cell version
Measuring cell
0.1 %
version
Factor FMZ 1
Additional factor through Turn Down
The additional factor F
F = 0.5 x TD + 0.5
TD
In the table, example values for typical Turn downs are listed.
Turn Down TD 1 : 1
Factor FTD 1
Thermal change current output through ambient temperature
56
at TD 1 : 1
TBasis
Measuring cell - Standard
0.1 % (with
measuring
range 25 mbar)
3
through Turn down is calculated according to the following formula:
TD
TD 2.5 : 1
1.75
Measuring cell climate-compensated, depending
on measuring range
5 bar, 10 bar, 1 bar, 2.5 bar
25 bar
1 2
TD 5 : 1 TD 10 : 1
3 5.5
in chapter "
T
0.4 bar
3
TD 20 : 1
10.5
VEGABAR 86 • 4 ... 20 mA