User Documentation

4 2555600000/02/05-2018
Scope and denitions
1.1 Scope
This safety manual applies to the safety relay
SCS 24VDC P1SIL3 I 2500980000
from the Weidmüller SAFESERIES product family.
Manufacturer:
Weidmüller Interface GmbH & Co KG
Klingenbergstraße 16
32758 Detmold
Germany
Certication body:
TÜV NORD CERT GmbH
Zertizierungsstelle
Maschinen
Benannte Stelle 0044
Langemarckstraße 20
45141 Essen
Germany
The safety relay fulls the safety integrity lev-
el 3 (SIL 3) for low and high demand modes of
operation. The device is certied according to
EN 61508:2010 and may bear the following TÜV
certication mark.
Certicate Registration No
44 207 13773712
1.2 Terms and abbreviations
Safety Integrity Level (SIL):
Four discrete levels (SIL1 to SIL4). The higher the
safety integrity level of a safety-related system, the
lower the probability that it will not perform the re-
quired 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):
VAverage 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.
1 Scope and denitions