MEDC LD15 - Manuel (Page 9)

Assessment of Functional Safety
This Beacon is intended for use in a safety system conforming to the requirements of IEC61508.
Sira Test & certification Ltd has conducted a Failure Modes Effect and Diagnostic Analysis (FMEDA) of the LD15
Xenon Beacon against the requirements of IEC 61508-2 using a Proof Test Interval of 8760hrs.
The results are shown below and are based on Route 1H.
The Beacon is classed as a Type B device
Safety Function:
‘To provide an intermittent or permanent spherical visual warning light upon demand’.
Summary of Clauses
2/7.4.2 and 2/7.4.4
LD15 LED Beacon
Single Mode (1oo1)
LD15 LED Beacon
Redundant Mode (1oo2)
Verdict
HFT=0 HFT=1 Type B
Architectural constraints
Safe Failure Fraction (SFF)
60% 60% SIL 1
Random hardware
failures: [h
-1 ]
!
DD
!
DU
0.00E+00
3.44E-08
0.00E+00
3.45E-09
!
Random hardware
failures: [h
-1 ]
!
SD
!
SU
0.00E+00
5.16E-08
0.00E+00
5.19E-09
!
Diagnostic coverage (DC) 0.00% 0.00% !
PFD @ PTI = 8760Hrs
MTTR = 8 Hrs
1.51E-04 1.51E-05 !
Average freq. of dangerous failure
(high demand-PFH)[h
-1 ]
3.44E-08 3.45E-09
SIL 3
SIL 3
!
Hardware safety integrity
compliance
[
Route 1
H
Systematic safety integrity
compliance
See report R56A31253B
Systematic Capability
(SC1, SC2, SC3, SC4)
SC2 (R56A31253B)
Hardware safety integrity achieved Limited to: SIL 1 (1oo1) & SIL 2 (1oo2) due to SFF value.
© MEDC 2015 01/15