Sample application
Operating manual ASP 5001
ID 442181.07
WE KEEP THINGS MOVING
21
6
DC
avg
•
SB 1:
DC = 99 % for the B1 and B2 position switches is based on the comparison of both input signals in the K1
safety switching device. This also corresponds to the DC
avg
for this subsystem (high).
•
SB 3:
For the T1a switchoff path, DC = 90 % is estimated when there is acknowledgement of the enable status
via a binary output and a coupling relay at the K1 safety switching device. Without the inclusion of an
acknowledgement signal from T1a in the feedback loop K1, DC = 60 % can only be assumed for fault
coverage by the process.
DC = 99 % for the T1b safety relay results from the direct monitoring of the positively-driven contact by
K1. With feedback from T1a, this results in a DC
avg
= 91.9 % (average) and 68.2 % (low) without T1a
feedback.
CCF
The minimum requirements are met, see section 7.2
Subsystem
Calculation
Failure probability
DC 60% for T1a
DC 90% for T1a
SB 1
SISTEMA
PFH
d
= 2.47
10
-8
h
-1
PFH
d
= 2.47
10
-8
h
-1
SB 2
Manufacturer's
specifications
PFH
d
= 2,31
10
-9
h
-1
PFH
d
= 2,31
10
-9
h
-1
SB 3
Manufacturer's
specifications
a)
a) see table in section 7.1
PFH
d
= 3,47
10
-9
h
-1
PFH
d
= 2,61
10
-9
h
-1
Total
—
PFH
d
= 3,04
10
-8
h
-1
PFH
d
= 2,96
10
-8
h
-1
