System Effectiveness Evaluation Using Star and Delta Transformations

This paper derives equations for probability of success/failure and failure rate for a delta-star transformation and vice versa. An iterative procedure is suggested to solve three nonlinear algebraic equations for evaluating probability of failure in a star-delta transformation. The delta-star transformation is highly accurate whereas the star-delta is not, but has reasonable accuracy. The star-delta transformation is recommended only when the delta-star transformation is not feasible during network reduction. For low (high) values of probability of failure and the failure rate, the star-delta transformation yields higher (lower) than exact values of system probability and frequency of failure.