Pepperl+Fuchs KFD2-SH-Ex1 - Page 11

Functional Safety KFD2-SH-Ex1(.T)(.OP), KHA6-SH-Ex1
Planning
2017-04
11
SIL 2 application
If you use output I or output II of the device, you can reach SIL 2 according to
IEC 61508.
• The device shall claim less than 10 % of the total failure budget for a SIL 2
safety loop.
• For a SIL 2 application operating in low demand mode the total PFD
avg
value
of the SIF (Safety Instrumented Function) should be smaller than 10
-2
, hence
the maximum allowable PFD
avg
value would then be 10
-3
.
• For a SIL 2 application operating in high demand mode the total PFH value of
the SIF should be smaller than 10
-6
per hour, hence the maximum allowable
PFH value would then be 10
-7
per hour.
• Since the safety loop has a hardware fault tolerance of 0 and it is a type A
device, the SFF must be > 60 % according to table 2 of IEC/EN 61508-2 for a
SIL 2 (sub) system.
PL d application
• If you use output I of the device, you can use the device in safety control loops
up to performance level PL d.
• The devices were qualified for use in applications acc. to EN/ISO 13849-1.
They fulfill PL d and are designed as Category 3 equipment. Consider the
rules for use given in this standard.