Siemens SITRANS LR200 Kurzanleitung Seite 19

How to select a passive barrier for SITRANS LR200
To make sure that the barrier safety description is suitable for the LR200 Intrinsically Safe (IS)
input parameters, carry out the following calculations:
Re-e = max. end-to-end resistance of the barrier
Rloop = loop resistance (total of cable resistance plus e.g. sense resistance,
displays, and/or PLC inputs)
Vbarrier = value of any non-linear voltage drops due to the barrier
1) Determine the value for Re-e from the data sheet.
2) Calculate the total value for Rloop: by adding, for example, sense resistance, displays,
and/or PLC inputs.
3) Calculate Rworking = Re-e + Rloop.
4) Determine the value of Vbarrier from the barrier data sheet (for example, voltage drops
due to diodes).
5) Calculate Vworking = Vsupply – Vbarrier.
Use the values for Vworking and Rworking to confirm that operation is within the shaded area
Curve 1 (General Purpose, Intrinsically Safe, Non-incendive)
of the graph
Notes:
• The following list is not exhaustive: there are many IS power supplies and barriers on the
market, which will work with the LR200.
• The PLC input modules and barriers listed below have all been tested and are functionally
compatible with the LR200.
Active barriers (repeating barriers)
Manufacturer
MTL
MTL
Stahl
Pepperl+Fuchs
Pepperl+Fuchs
MTL
MTL
Page EN-18 SITRANS LR200 (PROFIBUS PA) – QUICK START MANUAL
Part Number
706
7206
9001/51-280-110-14
KSD2-CI-S-Ex
KFD2-STC3-Ex1
E02009 - verify
E02010
on page 22.
7ML19985XD81