Emerson Rosemount 975HR, Reference Manual

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E SIL-2 features
This appendix details the special conditions to comply with the requirements of EN 61508
for SIL 2.
The Rosemount 975HR Flame Detector can only be used in low or high demand mode
applications; see IEC 61508.4, Chapter 3.5.12.
E.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: 3.3 x 10
-4
(≈ 3.3 percent of SIL-2) if only alarm relay is used for alerting.
— PFD: 3. 6 x 10
-4
(≈ 3.6 percent of SIL-2) if 0-20 mA interface is used as alarm.
— PFH: 1.6 x 10
-7
1/h (≈ 16.4 percent of SIL-2) for 0-20 mA application.
— SFF: 95 percent fulfills the conditions of EN 61508 for SIL-2.
• Alternative 2: Functional check of the detector every 365 days:
— HFT: 0
— PFD: 5.1 x 10
-4
(≈ 5.1 percent of SIL-2) if only alarm relay is used for alerting.
— PFD: 5.6 x 10
-4
(≈ 5.6 percent of SIL-2) if 0-20 mA interface is used as alarm.
— PFH: 1.6 x 10
-7
1/h (≈ 16.4 percent of SIL-2) for 0-20 mA application.
— SFF: 95 percent fulfills the conditions of EN 61508 for SIL-2.
E.2 Guidelines for configuring, installing,
operating, and service
The alert conditions according to SIL-2 can be implemented by an:
• Alert signal via 20 mA current loop
or
• Alert signal via alarm relay and the fault relay
E.2.1 Conditions for safe operating
1. The flame detector shall consist only of the approved hardware and software
modules.
2. The 24 V power supply must fulfill the requirements for PELV/SELV of EN 60950.
3. The automatic built-in test (BIT) must be activated.
Reference Manual SIL-2 features
00809-0100-4976 June 2021
Rosemount 975HR 75
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