Definition(s)
Periodic Tests
proof tests
planned operation performed at constant time interval in order to detect the potential hidden failures
which may have occurred in the meantime
Note 1 to entry: The unsafe hidden failures of a safety system which are not detected by the diagnostic tests may
be detected by periodic tests. Such tests are named “proof tests” in the standards dealing with functional safety
(e.g. IEC 61508[2]).
[SOURCE: IEC 61508]
Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards