Circuit breaker A mechanical life test of 18 circuit breakers of a new design was run to estimate the percentage failed by 10,000 cycles of operation. Breakers were inspected on a schedule, and it is known only that a failure occurred between certain inspections as shown.
(a) Make a Weibull plot with each failure as a separate point.
(b) How well does the Weibull distribution appear to fit the data?
(c) Graphically estimate the percentage failing by 10,000 cycles.
(d) What is your subjective estimate of the uncertainty in the estimate?
(e) Graphically estimate the Weibull shape parameter. Does the plot convince you that the true shape parameter differs from unity?
(f) The old breaker design had about 50% failure by 10,000 cycles. Is the new design clearly better?
(g) Another sample of 18 breakers of the new design was assembled under different conditions. These breakers were run on test for 15,000 cycles without failure and removed from test. Do you subjectively judge the two samples consistent?