Two-dimensional finite element modelling of overlap joints in transformer cores

The influence of overlap joints in transformer cores on the local flux and eddy current distribution and on overall transformer characteristics is stu died by means of two-dimensional finite element (2D FE) models. A simplifie d 2D FE model of a single overlap joint is used for estimating the resultin g increased magnetomotive force and increased eddy current losses. Both eff ects can be accounted for in a 2D FE model of the complete transformer by l ocally adopting modified material characteristics (viz. BH-curve and electr ical conductivity) in the cross-section of the core. This novel method is d emonstrated and validated by applying it to a three phase transformer The c alculated no-load currents and losses are compared to the measured ones.