Emerson Rosemount 3408, Reference Manual, Page: 32 / 104

4.3.5 Power supply
The transmitter operates on max. 35 Vdc transmitter terminal voltage and max. 22.5 mA
(max. 30 Vdc in Intrinsically Safe installations).
4.3.6 Load limitations
For HART
®
communication, a minimum loop resistance of 250 Ω is required. Maximum
loop resistance (R) is determined by the voltage level of the external power supply (U
E
):
U
E
(Vdc) R (Ω)
≥ 15.6 R = 44.4 × (U
E
− 12)
< 15.6 R = 250 × (U
E
− 15)
Figure 4-3: Load Limits
12 35 24
0
200
400
600
800
1000
UE (Vdc)
532
250
162
1021
17.6 15.6
R (Ω)
4.3.7 Wiring diagram
Figure 4-4: 4-20 mA/HART
®
Communication
-
+
-
+
C
F
D
B
A
E
A. Handheld communicator
B. Approved IS barrier (for Intrinsically Safe installations only)
C. HART modem
D. Load resistance (≥250 Ω)
E. Current meter
F. Power supply
Electrical installation Reference Manual
September 2022 00809-0100-4418
32 Emerson.com/Rosemount