Wound magnetic core consequences on false residual currents

Purpose - Geometric or magnetic anomalies in the wound magnetic core of a residual current circuit breaker can be responsible of its abnonnal tripping. The purpose of this paper is to analyse the core shape contribution to false residual currents (FRCs). Design/methodology/approach - To study precisely the core shape contribution, FEM simulations are investigated. First a 2D multilayer geometry is described thanks to linear regions. Then an apparent anisotropic bulk core is developed and validated in 2D and in 3D. Findings - The air gaps between the magnetic layers develop a shielding effect responsible of the core high sensibility to primary conductors eccentricity. This effect can be easily represented using an anisotropic: bulk core model. Research limitations/implications - The anisotropic material model is basic and has known limitations. Future research should see the development of a new model. Originality/value - FRCs can considerably disturb operation of residual cur-rent device. This paper provides new hypothesis on the origin of theses currents and proposes an anisotropic magnetic material model that simplifies FRC study.