Extreme overcurrent analysis for the protection of automotive circuit components

Abstract

A methodology for the protection of automotive circuit components, against the possible damaging effects of an overcurrent, is developed. In particular, a theoretical analysis of electrical fused-circuits, under extreme overcurrent conditions, is outlined. It is shown that the temperature rise of the fuse-element can be expressed in terms of the temperature rise of a particularly vulnerable circuit component, and vice versa. Furthermore, a precise condition is formulated which may be used as an aid to determine the range of nominal current ratings for fuses that will adequately protect the vulnerable component against the effects of over-heating. For pre-defined situations, results are presented which illustrate how the useful range of nominal current ratings depends on the steady-state properties of the circuit and the physical and geometrical properties of the circuit components.