In a step-lapped mitre core, the core steel is mitre cut and step stacked in groups of 5 -7 laminations at a time. In this arrangement, the grain orientation of the core steel lines up with the direction of the flux, which then flows parallel with the direction of the grain orientation.
Four main parts make up a dry-type transformer: the core, the coils, the terminals and the structural frame. The core’s job is to provide a path for the magnetic flux where the windings are linked, transferring energy from the primary winding to the secondary winding. When voltage is applied to the primary, current flows producing a magnetic field, or flux. Secondary voltage is induced due to the coupling of the secondary to the magnetic field.
Energy is required to magnetize the core. The amount of energy required depends on the composition of the core material, joints or air gaps within the core and the type of core construction. The four main types of core construction are wound cores, stamped laminations, butt-lapped cores and step-lapped miter cores.