Endress+Hauser prowirl 70 - Page 16

Electrical
Connection
Load R
L
[Ω]
Power supply voltage U
S
[V]
Permissible load
(with HART: min. 250 Ω)
ti031y18
Current output load
R
L
=
U
S
– U
Kl
I
max
⋅ 10
−
3
=
U
S
– 12
0.025
R
L
= load resistance
U
S
= power supply voltage (12...30 V DC)
U
Kl
= terminal voltage Prowirl (min. 12 V DC)
I
max
= output current (25 mA)
Note:
Where data transfer takes place over the 4...20 mA line via HART protocol
(→ hand-held device), the minimum load resistance is 250 Ω.
The supply voltage must be high enough to supply 12 V DC at the Prowirl terminals.
The above diagram shows the required supply voltage for varying load resistance.
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