A Two Non–identical Unit Standby Complex System

The present paper deals with a system composed of two non –identical units A and B. Unit-A consists of two non identical components A1 and A2 in series form, whereas unit -B consists of only one component, which is different from the components of unit-A . Initially the unit –A is operative and the unit-B is kept into cold standby. For the successful operation of the system either both the components A1 and A2 of unit-A or the unit-B is good. As soon as any component of unit-A fails, the unit-B kept into cold standby becomes operative instantaneously with the help of a perfect and instantaneous switching device. Each component of unit-A as well as unit-B has two modes Normal (N) and total failure (F). A single repair man is available to repair each component of failed unit-A as well as failed unit-B and the priority in repair is given to unit-A over the unit-B. The failure rate of each component of unit-A is taken constant with different parameters where as the failure rate of the unit-B is taken general. The distribution of time to repair of each component of unit-A and unit-B are also taken general with different CDF’s. A repaired unit always works as good as new. Using regenerative point technique, various important measures of system effectiveness have been obtained.