Impedance Range Of Signal Loop - Dräger PIR 7000 Technical Handbook

Assembly and Installation
Multidrop installation with HART
+
U
–
R
S
U – 9 V
R (per core) <
cable
n x 1.8
n = actual number of gas transmitters at
the power supply
U = voltage output in V of power supply
for output current of 0.9 A
= 230 ... 500 Ω
R
S

Impedance Range of Signal Loop

Operating mode
Operation without
®
HART communica-
tion
Operation with
®
HART communica-
®
tion (HART opera-
tion)
®
HART multidrop
operation
1)
The impedance is the addition of the loop resistance R
20
®
communication and a (central) power supply:
Ω
Figure Impedance range of signal
1)
loop
0 to 80 Ω
linear rise with supply voltage
Figure 1
from:
page 21
0 to 80 Ω at 9 V to
0 to 500 Ω at 18 V
0 to 500 Ω
230 to 270 Ω
linear rise with supply voltage
Figure 2
from:
page 21
230 to 270 Ω at 13 V to
230 to 500 Ω at 18 V
230 to 500 Ω
Figure 3
230 to 500 Ω
page 22
and the line resistance R
S
1 2 3 4 5 6
1 2 3 4 5 6
1 2
of the signal loop.
cable
1 2 3 4 5 6
. . . . . . . . . . . . . .
8
Range of supply
voltage
at 9 V DC
9 to 18 V DC
18 to 30 V DC
at 13 V DC
13 to 18 V DC
18 to 30 V DC
9 to 30 V DC