NEARLY-OPTIMUM SELECTION OF STRENGTH t ORTHOGONAL ARRAYS: A STRENGTH AND EFFICIENCY APPRAISAL

Abstract

The process of enumeration and construction of orthogonal arrays has been extensively studied
and several methods to develop and implement them have been proposed. There is, however, a gap in the
literature when deciding the most appropriate orthogonal array to be tailored to a specific situation. Romero
and Murray [1] presented a combinatorial-based technique to list all the possible isomorphic arrays for a given
design type and undertook the enumeration of almost all of them (up to 100 runs). The size of the orbits under
consideration (the number of isomorphic arrays or possible arrangements for the same design type) was found
very large. Certainly, the decision to select the most suitable array for a given situation becomes a non-trivial
and computationally intensive task. Some attempts to overcome this problem have been proposed [2] [3], yet
a context-based approach has not fully been taken into consideration. In this paper, an engineering-based
approach is presented to select orthogonal arrays according to their isomorphism and experimental
implementation. The arrays were simulated and tested using a protective relay and its associated circuits.
Although still in the process of testing, preliminary results show important performance advantages over
traditional techniques such as crossed arrays, combined arrays and response surface methods.