MEDC DB3 Technische Anleitung Seite 9

Assessment of Functional Safety
This Sounder is intended for use in a safety system conforming to the requirements of IEC61508.
S
Sira Test & certification Ltd has conducted a Failure Modes Effect and Diagnostic Analysis (FMEDA)
of the DC version of DB3 Sounder against the requirements of IEC 61508-2 using a Proof Test
Interval of 8760hrs.
The DC version of the Beacon was considered to be the worst case. The results are shown below and
are based on Route 2
T
H
The Sounder is classed as a Type B device
To provide a pre-described audible warning sound when required'
Architectural constraints:
Probability of failure on
demand:
Probability of Dangerous
failure on safety function:
Hardware safety integrity
compliance
Systematic safety integrity
compliance
Systematic Capability
Overall SIL-capability
achieved
Conditions of Safe use
The following conditions apply to the installation, operation and maintenance of the assessed
equipment. Failure to observe these may compromise the safety integrity of the assessed equipment:
1. The user shall comply with the requirements given in the manufacturer's user documentation
(This Safety Manual and Technical manual) in regard to all relevant functional safety aspects
such as application of use, installation, operation, maintenance, proof tests, maximum ratings,
environmental conditions, repair, etc;
2. Selection of this equipment for use in safety functions and the installation, configuration, overall
validation, maintenance and repair shall only be carried out by competent personnel, observing all
the manufacturer's conditions and recommendations in the user documentation.
3. All information associated with any field failures of this product should be collected under
a dependability management process (e.g., IEC 60300-3-2) and reported to the
manufacturer.
4. The unit should be tested at regular intervals to identify any malfunctions; in accordance with this
safety manual.
© ooper MED 2011
P
Proven in use (PIU) of IEC61508-2.
Proven in Use Summary Table
Safety Function of DB3 Sounder:
Clause 7.4.4.3.1 states:
HFT = 0
Highest SIL capable through PIU
would be SIL2 for a Low Demand
application.
PFD =1.02E-03
AVG
(Low Demand Mode)
PFH = 2.35E-07
(High Demand Mode)
DB3 SOUNDER
Proof Test
Interval=8760Hrs
MTTR = 8 Hrs
Route 2
Route 1
SC2
SIL 2 (Low Demand)
SIL 2
(Low Demand
Mode)
SIL 2
N/A
H
S
08/11