Development of high permeability cores for earth leakage protectiondevices

摘要

Nickel-iron differential transformer cores are used in residualcurrent devices (RCDs) for the prevention of electric shock caused by aleakage of current to earth through the human body. Essential to theeffectiveness of an RCD is the magnetic performance of this nickel-ironcore. The Teaching Company Scheme programme at Telcon Ltd., incollaboration with the University of Brighton, UK, has been concernedwith improving core performance by modifying the intrinsic magneticproperties of the alloy and improving the core fabrication andheat-treatment processes required to realise these properties. Thispaper describes techniques that have been developed through appliedresearch in order to achieve these aims