SIL-2 Features
Appendix E:
SIL-2 Features
E.1
40/40R Flame Detector
This appendix details the special conditions for compliance with the requirements
of EN 61508 for SIL 2.
The 40/40R Flame Detector can only be used in low demand mode applications.
See IEC 61508.4, Chapter 3.5.12.
E.1.1
Safety Relevant Parameters
Perform the following functional checks of the detector:
•
Alternative 1
: Functional check of the detector every 180 days:
•
HFT
: 0
•
PFD
: 2.4 x 10
-4
(≈ 2.4% of SIL
-2) if only alarm relay is used for alerting.
•
PFD
: 2.6 x 10
-4
(≈ 2.6% of SIL
-2) if 0
–
20mA interface is used.
•
SFF
: 95% fulfills the conditions of EN 61508 for SIL2
•
Alternative 2
: Functional check of the detector every 365 days:
•
HFT
: 0
•
PFD
: 3.2 x 10
-4
(≈ 3.2% of SIL
-2) if only alarm relay is used for alerting.
•
PFD
: 3.7 x 10
-4
(
≈ 3.6% of SIL
-2) if 0
–
20mA interface is used to signal
current as alarm.
•
SFF
: 95% fulfills the conditions of EN 61508 for SIL2
E.1.2
Guidelines for Configuring, Installing, Operating, and Service
The alert conditions according to SIL 2 can be implemented by an:
•
Alert signal via 20mA current loop
Or
•
Alert signal via alarm relay and the fault relay
E.1.2.1
Conditions for Safe Operating
•
The flame detector must consist only of the approved hardware and software
modules.
•
The 24V power supply must fulfill the requirements for PELV/SELV of EN
60950.
•
The automatic BIT (Built-In-Test) must be activated.
•
The setup parameters must be verified (as described in
on page 79, and in
Using the Alarm Relay Contact for
on page 80.
