Siemens SITRANS LR250 Guide De Mise En Service Rapide page 12

Intrinsically Safe wiring (continued)
Device nameplate (FM/CSA)
The FM/CSA Intrinsically Safe connection drawing
number 23650653 can be downloaded from the product page of our website at:
www.siemens.com/LR250. Go to Support > Installation Drawings > Level Measurement >
Continuous - Radar.
• For power demands see
Energy Limited/ Non-incendive
• For wiring requirements: follow local regulations.
• Approved dust-tight and water-tight conduit seals are required for outdoor NEMA 4X /
type 4X / NEMA 6, IP67, IP68 locations.
Instructions specific to hazardous area installations
• Refer to
• Recommended intrinsically safe barriers are listed under
Active barriers (repeating barriers)
on page 10 and
Note: Selecting a suitable PLC input module, power supply, or barrier 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.
Passive Shunt Diode Barriers
Note: A well regulated supply voltage is required.
Manufacture
MTL
MTL
Stahl
Stahl
How to select a passive barrier for SITRANS LR250
To make sure that the barrier safety description is suitable for the LR250 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 any additional series
resistance, for example, PLC inputs and/or displays)
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.
3) Calculate Rworking = Re-e + Rloop.
Page EN-10 SITRANS LR250 (HART) – QUICK START MANUAL
Curve 1: General Purpose, Intrinsically Safe, Non-Sparking/
on page 23.
Part Number
787SP+ (Dual Channel)
7787P+ (Dual Channel)
9001/01-280-100-10 (Single Channel)
9002/01-280-110-10 (Dual Channel)
on page 13.
Passive Shunt Diode Barriers
on page 11.
A5E31997170