Deltabar S
Endress+Hauser 27
Appendix
Measuring system design System components
A0028746
1 SPS (programmable logic controller)
2 Transmitter power supply unit, e.g. RN221N (with communication resistor)
3 Connection for Commubox FXA191, FXA195 and Field Communicator
4 HART handheld terminal, e.g. Field Communicator
5 Computer with operating tool
6 Commubox FXA191 (RS232) or FXA195 (USB), FXA291
7 Field Xpert
8 VIATOR Bluetooth modem with connecting cable
9Transmitter
An analog signal (4-20 mA) in proportion to the pressure is generated in the transmitter. This is sent
to a downstream logic unit (e.g. PLC, limit signal transmitter, etc.) where it is monitored to determine
whether it is below or above a specified limit value.
For fault monitoring, the logic unit must recognize both HI-alarms (≥21.0 mA) and LO-alarms
(≤ 3.6 mA).
Notes on the redundant
connection of multiple
sensors for SIL 3
With redundant connection with HFT = 1 (e.g. 1oo2 or 2oo3 architecture), the Deltabar S meets the
requirements for SIL 3.
The common cause factors and
D
indicated in the table below are minimum values for the
Deltabar S. These values should be used when calculating the failure probability of redundantly
connected Deltabar S units as per IEC 61508-6.
The system-specific observation can return higher values depending on the actual installation and the
use of other components (e.g. Ex barriers).
Additional information
Minimum value with homogeneous redundant use 5 %
Minimum value
D
with homogeneous redundant use 2 %
General information on functional safety (SIL) is available at:
www.de.endress.com Search Functional safety and in the Competence Brochure
CP01008Z/11 "Functional Safety in the Process Industry - Risk Reduction with Safety
Instrumented Systems".
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