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Application and Function
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33003405 07/2007
Offline Proof-Test
Overview The offline proof-test recognizes dangerous concealed faults that would affect the
safe function of the plant.
Safety systems have to be subjected to an offline proof test in intervals of 10 years.
By an analysis using the calculation tool SILence, the interval often may be
extended. (SILence is a separate program. Contact the service for more information
or take a look at the HIMA homepage for a test version of the software SILence.)
For relay modules, the proof test for the relays has to be carried out in intervals
defined for the respective plant.
Execution of the
Offline Proof
Test
The execution of the offline proof test depends on the configuration of the plant
(EUC = equipment under control), which risk potential it has, and which standards
for operation are applied and form the bases for the approval by the test authority in
charge.
According to the standards IEC 61508 1-7, IEC 61511 1-3, IEC 62061, and
VDI/VDE 2180 sheet 1 to 4, in case of safety-related systems the operating
company has to arrange for proof tests.
Periodic Proof
Testing
The modules can be proof tested by executing the full safety loop.
In practice the input and output field devices have a more frequent proof test interval
(e.g., every 6 or 12 months) than the modules. If the end-user tests the complete
safety loop because of the field devices then the modules are automatically included
in these tests. No additional periodic tests are required for the modules.
If the proof test of the field devices does not include the modules then the PES needs
to be tested as a minimum once in 10 year. This can be done by executing a reset
of the modules.
In case there are periodic proof test requirements for specific modules then the end-
user should refer to the data sheets of these modules.