Siemens Sitrans LR200, Quick Start Manual, Page: 24 / 276

7ML19985XC81 SITRANS LR200 (HART) – QUICK START MANUAL Page EN-23
m
mmmm
Englis
h
Allowable operating area
Curve 1 (General Purpose,
Intrinsically Safe, Non-
incendive)
Loop Voltage versus Loop
Resistance
Curve 2 (Flameproof,
Increased Safety, Explosion-
proof)
Loop Voltage versus Loop
Resistance
Startup Curve
Power Supply Requirements
0
100
200
300
400
500
600
700
800
900
15 17 19 21 23 25 27 29
Loop Voltage - V
L
(Source Voltage)
Loop
R
es
is
ta
n
ce
-R
L
Curve 1: Power Supply Requirements
Loop Voltage – VL
Loop R
esist
anc
e – RL
ALLOWABLE
OPERATING AREA
RL=44.6*VL – 493.4
(30.0v,845 ohms)
(17.8v, 300 ohms)
RL=272.7*VL – 4554.1
(16.7v, 0 ohms)
Power Supply Requirements
0
50
100
150
200
250
300
350
400
15 20 25 30
Loop Voltage - V
L
(Source Voltage)
Loop
R
e
s
is
ta
n
c
e
-
R
L
Curve 2: Power Supply Requirements
Loop Voltage – VL
Loop R
esist
anc
e –
RL
ALLOWABLE
OPERATING AREA
RL=44.6*VL – 493.4
(30.0v,845 ohms)
(17.8v, 300 ohms)
RL=272.7*VL – 4554.1
(16.7v, 0 ohms)
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35 40 45 50 55
Time (secs)
Cu
rr
en
t(
m
A
)
No Current Limit Current Limited Power Supply
No current limit
Current-limited power
Time (seconds)
Loop Power Supply
(no Current Limit)
Loop Power
Supply with 25 mA
Current Limit
actual material level
(example value 18 mA)
Cu
rr
ent (mA)
Note: At startup, it can take
anywhere from 25 to 55 seconds
for the device to report the actual
material level.