VEGA VEGAPULS 66 (≥ 2.0.0 - ≥ 4.0.0) enamel 4 … 20 mA_HART - four-wire - Manual (Page 60)

60
11 Supplement
VEGAPULS 66 enamel • 4 … 20 mA/HART - four-wire
36528-EN-121011
Ʋ Air pressure 860 … 1060 mbar/86 … 106 kPa (12.5 … 15.4 psig)
Installation reference conditions
Ʋ Min. distance to installations > 200 mm (7.874 in)
Ʋ Reflector Plane plate reflector
Ʋ False reflections Largest false echo 20 dB smaller than the useful echo
Deviation with liquids See following diagrams
1,0 m (3.28 ft)
20 mm (0.788 in)
- 20 mm (- 0.788 in)
0
8 mm (0.315 in)
- 8 mm (- 0.315 in)
1 2 3
Fig. 43: Deviation under reference conditions
1 Reference plane
2 Antenna edge
3 Recommended measuring range
Reproducibility ≤ ±1 mm
Variables influencing measurement accuracy
Specifications apply to the HART signal and the current output
Temperature drift - Digital output
±3 mm/10 K relating to the max. measuring range or
max. 10 mm
Additional deviation through strong, high
frequency electromagnetic fields acc. to
EN 61326
< ±50 mm
Specifications apply also to the current output
Temperature drift - Current output
±0.03 %/10 K relating to the 16 mA span max. ±0.3 %
Deviation on the current output by ana-
logue/digital conversion
< ±15 µA
Deviation on the current output due to
strong, high frequency electromagnetic
fields acc. to EN 61326
< ±150 µA
Influence of the superimposed gas and pressure to the accuracy
The propagation speed of the radar impulses in gas or vapour above the medium is reduced by
high pressure. This effect depends on the superimposed gas or vapour and is especially large at
low temperatures.
The following table shows the resulting deviation for some typical gases and vapours. The specified
values refer to the distance. Positive values mean that the measured distance is too large, negative
values that the measured distance is too small.