This part of IEC 60605 specifies procedures to verify the assumption of a constant failure rate or constant failure intensity as defined in IEC 60050(191). These procedures are applicable whenever it is necessary to verify these assumptions. This may be due to a requirement or for the purpose of assessing the behaviour in time of the failure rate or the failure intensity.
The tests specified in this International Standard are one of the following:
- to test whether the times to failure of items are exponentially distributed, i.e. the failure rate is constant;
- to test whether the times between failures of a single repaired item do not have any time trend, i.e. the failure intensity does not exhibit an increasing or decreasing trend.