BS EN IEC 61124:2023

Reliability testing. Compliance tests for constant failure rate and constant failure intensity. | Status: Current

1 Scope This document gives a number of optimized test plans, the corresponding border lines and characteristics. In addition, the algorithms for designing test plans using a spreadsheet program are also given, together with guidance on how to choose test plans. This document specifies procedures to test whether an observed value of

• - failure rate,
• - failure intensity,
• - mean operating time to failure (MTTF),
• - mean operating time between failures (MTBF),

conforms to a given requirement. It is assumed, except where otherwise stated, that during the accumulated test time, the times to failure or the operating times between failures are independent and identically exponentially distributed. This assumption implies that the failure rate or failure intensity is assumed to be constant. Four types of test plans are described as follows:

• - truncated sequential probability ratio test (SPRT);
• - fixed time/failure terminated test (FTFT);
• - fixed calendar time terminated test without replacement;
• - combined test.

This document does not cover guidance on how to plan, perform, analyse and report a test. This information can be found in IEC 60300‑3‑5. This document does not describe test conditions. This information can be found in IEC 60605‑2 and in IEC 60300‑3‑5.