View solution to the question:
a. Explain circumstances in which it is possible to improve maintainability to counteract poor reliability, and also identify circumstances where this approach is unrewarding.
b. The expression for steady-state availability of a single element is:
Explain what is meant by a steady state. State the meanings of the symbols Î¼ and Î», and the assumptions inherent in the expression.
(a) Standby redundancy is achieved when one unit does not operate continuously hut is only switched on when the primary unit fails. A standby electrical generating system is an example. The block diagram in Figure shows another. The standby unit and the sensing and switching system may be considered to have a â€˜one-shotâ€™ reliability R of starting and maintaining system function until the primary equipment is repaired, or R, may be time-dependent. The switch and the redundant unit may have dormant hazard rates, particularly if they are not maintained or monitored