ABB FSO-21, Руководство пользователя

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Technical data 531
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Relevant failure modes
The following failure modes related to the outputs of the FSO-21 with or without
FSE-31 have been considered in the design:
• STO output
• PROFIsafe
• Digital outputs.
The relevant dangerous failure mode due to internal random hardware failure of
FSO-21 with/without FSE-31 are that these outputs are not activated on command.
The probabilities of the dangerous undetected failures of the safety functions are
given in the basic safety table.
FSO-21 and FSE-31 implement several diagnostics to detect internal random
hardware failures. The diagnostics cycle time for each of the channels is 10 hours or
less. The diagnostics of each channel is separate and independent of the other
channel.
The relevant failure mode of the diagnostics is that, due to a random hardware fault in
the diagnostic system, the fault reaction is not performed while a detectable fault in
the safety function is present.
For FSO-21 with or without FSE-31 module, there are no dangerous failures that are
not detected by the diagnostics.
2-channel
pulsed DI
Logic
STO-output
2-channel
pulsed output
Speed
measurement
6.4E-08 9.9E-05 9.9E-04 - 96.8 1 3 1110 95.9 3 e
2-channel non-
pulsed DI
Logic
STO-output
2-channel non-
pulsed output
Speed
measurement
6.4E-08 1.0E-04 9.9E-04 - 96.8 1 3 1115 94.4 3 e
PROFIsafe
Logic
STO-output
Speed
measurement
6.5E-08 1.1E-04 1.0E-03 - 96.8 1 3 2512 96.6 3 e
3AXD10001287182 C
1) Lowest subsystem SFF
2) Lowest subsystem DC
Subsystems
used in the
safety function PFH
(1/h)
PFD
avg
PFD
avg
PFD
avg
SFF
1)
HFT SIL MTTF
D
DC
2)
Cat. PL
(T1 = 20 a) (T1 = 2 a) (T1 = 5 a) (T1 = 20 a) (%) (a) (%)