Loop Voltage Versus Loop Resistance; Is Safety Barrier Selection; How To Select A Passive Barrier For Sitrans Probe Lu; Power Supply Requirements - Siemens sitrans PROBE LU Instruction Manual

Loop Voltage versus Loop Resistance

1000
900
800
700
600
500
400
300
200
100
0
10.00

IS Safety Barrier Selection

Selecting a suitable barrier or power supply requires knowledge about Intrinsic Safety
and the application. It is the responsibility of the installer to ensure that the intrinsically
safe installation complies with both the apparatus approval requirements and the
relevant national code of practice.

How to select a passive barrier for SITRANS Probe LU

1. Make sure that the barrier safety description is suitable for the SITRANS Probe LU
Intrinsically Safe (IS) input parameters.
2. Determine the maximum end-to-end resistance of the barrier (Re-e) from the data
sheet.
3. Determine other loop resistance (Rloop): for example, sense resistance, displays,
and/or PLC inputs.
4. Calculate Rworking = Re-e + Rloop.
Page 88

Power Supply Requirements

(17.8v, 300 ohms)
RL=272.7*VL - 4554.1
(16.7v, 0 ohms)
15.00
SITRANS Probe LU – INSTRUCTION MANUAL
(30.0v,845 ohms)
RL=44.6*VL - 493.4
ALLOWABLE OPERATING
20.00
Loop Voltage-V
L
(Source voltage)
AREA
25.00 30.00
7ML19985HT01