Wound magnetic core consequences on false residual currents

Abstract

PurposeGeometric or magnetic anomalies in the wound magnetic core of a residual current circuit breaker can be responsible of its abnormal tripping. The purpose of this paper is to analyse the core shape contribution to false residual currents (FRCs).Design/methodology/approachTo 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.FindingsThe 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/implicationsThe anisotropic material model is basic and has known limitations. Future research should see the development of a new model.Originality/valueFRCs can considerably disturb operation of residual current device. This paper provides new hypothesis on the origin of theses currents and proposes an anisotropic magnetic material model that simplifies FRC study.