SIL-2 Features
TM40/40U Rev. (Af), February 2019
79
Appendix E:
SIL-2 Features
E.1
40/40UB Flame Detector
This appendix details the special conditions for compliance with the requirements
of EN 61508 for SIL 2.
The 40/40UB 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 every 30 days:
•
HFT
: 0
•
PFD
: 2.5 x 10
–
5
(≈ 0.
2% of SIL-2) if only alarm relay is used for alerting.
•
PFD
: 2.8 x 10
–
5
(≈
0.3% of SIL-2) if 4
–
20mA interface is used as alarm.
•
SFF
: 97% 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.
•
The function of the 40/40 Flame Detector (flame detection, function of the 0
–
20mA interface, and relay functions) must be checked completely.