1 Scope
Where functional reliability is required by general safety standards, one aspect of demonstrating this reliability
is testing performed on-line during plant operation or during plant shutdown in preparation
for return to power operation.
This standard lays down principles for testing I&C systems performing category A,
B and C functions, per IEC 61226, during normal power operation and shutdown, so as to check the functional availability especially with regard to the detection of faults that could prevent the proper operation
of the functions important to safety. It covers the possibility of testing at short
intervals or continuous surveillance, as well as periodic testing at longer intervals. It also establishes basic rules for the design and application
of the test equipment and its interface with the systems important to safety. Further,
the effect of any test equipment failure on the reliability of the I&C systems is
considered.
Types of surveillance tests may include:
– self-tests for I&C equipment;
– test of a group of equipment or components to confirm properties that support the
safety function (continuity, power availability , etc.);
– test based on information redundancy or comparison of control signatures (consistency
checking for redundant sensors, CRC-...