QUALITATIVELY MODELING THE EFFECTS OF ELECTRICAL CIRCUIT FAULTS

This paper presents a new method for the qualitative analysis of electrical circuit behaviour. This paper shows that a qualitative representation of electrical resistance provides a good intuitive model for reasoning about gross electrical effects due to connectivity faults. The motivation is to produce tools to assist engineers in the identification and analysis of circuit failures that have safety implications. This includes work in hazard analysis, safety-critical systems, and failure mode effects analysis (FMEA). The analysis algorithms efficiently locate state changes in circuits and assign qualitative symbols for voltage and current flow to all components. The input, DELTAr, is a list which specifies qualitative resistance changes between the nodes of a previously defined circuit and the output is a pair, (P(a), P(d)), of sets of activated and deactivated paths, identifying the components that have changed state. The system has a layered priority approach precisely in keeping with failure mode analysis tasks and has been successfully tested in real applications.