kcd2-sr--ex- Pepperl+Fuchs, kcd2-sr--ex- Datasheet - Page 9

• Manufacturer Part Number: kcd2-sr--ex-
• Description: Process Automation
• Manufacturer: Pepperl+Fuchs

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3.1
3.2
3.3
SAFETY MANUAL SIL KCD2-SR-(EX)*.(LB), HIC282*
Safety Recommendation
Safety Recommendation
Interfaces
The device has the following interfaces. For corresponding terminals see data sheet.
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Configuration
The device must be configured through the user accessible DIP switches for the required
output function before the start-up. During the functionality any change of the operating function
(DIP switch modification) can invalidate the safety function behavior and must be avoided.
The KCD2 devices provide a suitable cover to protect against accidental changes while on the
HiC devices the access to the DIP switch is permitted only through a small window on the side
and by a small screw driver.
Useful Life Time
Although a constant failure rate is assumed by the probabilistic estimation this only applies
provided that the useful life time of components is not exceeded. Beyond this useful life time,
the result of the probabilistic calculation is meaningless as the probability of failure significantly
increases with time. The useful life time is highly dependent on the component itself and its
operating conditions – temperature in particular (for example, the electrolytic capacitors can be
very sensitive to the working temperature).
This assumption of a constant failure rate is based on the bathtub curve, which shows the
typical behavior for electronic components.
Therefore it is obvious that failure calculation is only valid for components that have this
constant domain and that the validity of the calculation is limited to the useful life time of each
component.
It is assumed that early failures are detected to a huge percentage during the installation period
and therefore the assumption of a constant failure rate during the useful life time is valid.
However, according to IEC 61508-2, a useful life time, based on experience, should be
assumed. Experience has shown that the useful life time often lies within a range period of
about 8 ... 12 years.
Our experience has shown that the useful life time of a Pepperl+Fuchs product can be higher
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Please note that the useful life time refers to the (constant) failure rate of the device. The
effective life time can be higher.
Safety relevant interfaces:
KFD2-SR-(Ex)1, HiC2821: input I, output I, output II
KFD2-SR-(Ex)2, HiC2822: input I, input II, output I, output II
Non-safety relevant interfaces: output ERR
if there are no components with reduced life time in the safety path (like electrolytic
capacitors, relays, flash memory, opto coupler) which can produce dangerous undetected
failures and
if the ambient temperature is significantly below 60 °C.
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