Setting Test Intervals and Allowable Bypass Times as a Function of Protection System Goals

This analysis demonstrates the usefulness of availability design goals for determining required periodic test intervals and allowable bypass times as permitted by IEEE-279 criteria. Formulas are developed for calculating these times for instrumentation logic configurations common to reactor protection systems. Both simultaneous and uniformly staggered test schedules are considered. In addition to sample problems illustrating the application of these formulas, nomographs are presented for rapid graphical determination of test intervals and bypass times.