User Documentation

5
Scope and standards
1438130000/02/07-2018
1.1 Scope
This safety manual applies to SIL3 relays from
Weidmüller‘s SAFESERIES for the following items
produced after 11/2012:
SCS 24VDC P2SIL3ES 1319280000
SIL3 relays in the SCS 24VDC P2SIL3ES series
from
Weidmüller Interface GmbH & Co KG
Klingenbergstraße 16
32758 Detmold
Germany
have been certied by
TÜV NORD CERT GmbH
Certication Body
Maschinery
Notied Body 0044
Langemarckstr. 20
45141 Essen
Germany
according to EN 61508 SIL3. They are certied
as “EC type-examination” for use in “low demand
mode” and “high demand mode” systems.
CerticateRegistrationNo:
44 205 12 413770-001
1 Scope and standards
1.2 Abbreviations
SafetyIntegrityLevel(SIL):
Four discrete levels (SIL1 to SIL4). The higher the
SIL of a safety-related system, the lower the prob-
ability that it will not perform the required safety
functions.
AverageProbabilityofFailureonDemand
(PFD
avg
):
Average probability of failure of a safety function
working in low demand mode of operation.
ProbabilityofFailureperHour(PFH):
Average probability of failure of a safety function
working in high demand or continuous mode of op-
eration.
SafeFailureFraction(SFF):
Percentage part of safe failures and dangerous de-
tected failures of a safety function or a sub-system
related to all failures.
HardwareFaultTolerance(HFT):
HFT = n means, that n+1 faults could cause a loss of
the safety function.
Lowdemandmodeofoperation:
Frequency of demands on a safety-related system
no greater than one per year and no greater than
twice the proof-test frequency.
Highdemandorcontinuousmodeofoperation:
Frequency of demands on a safety-related system
greater than one per year or greater than twice the
proof-test frequency.
DevicetypeA(simplesubsystem):
The failure modes of all constituent components are
well dened and the behaviour under fault conditions
can be completely determined.