An overview of the recent developments of the inter-laminar short circuit fault detection methods in magnetic cores

Inter-laminar short circuit faults between laminations of the magnetic cores increase core losses and could cause major damage to electrical machines. In this paper, first causes and consequences of inter-laminar faults in magnetic cores are presented. Different types of inter-laminar fault detection methods are then presented and discussed. In the relevant studies, advantages and disadvantages of each method is highlighted. Finally, experimental results of an electro-magnetic fault detection method based on Flux Injection Probe is presented.

I. Introduction

MAGNETIC cores of electrical machines are constructed from laminations of electrical steel material alloyed with silicon to minimise the hysteresis and eddy current losses and achieve high efficiency operation [1]. Magnetic laminations are isolated on both sides using insulating materials to prevent electrical conduction between them and restrict the circulation of eddy currents [2]. However since the materials used for the inter-laminar insulation are susceptible to decline and damage, short circuits between the laminations due to electrical failure could happen due to a number of reasons as follow [3]–[4].