Fundamental and harmonic flux behaviour in a 100 KVA distribution transformer core

A commercial 100 KVA, 3-phase distribution transformer core has been investigated in order to obtain a detailed study of flux distribution in various packets of the limbs and yokes. The core was chosen to be compatible with model cores used earlier in various experimental works. Variations of flux density from packet to packet at low excitation of 0.9 Tesla were 46% in the yokes and 28% in the limbs. At a higher core excitation, 1.7 Tesla, variation in the yokes dropped to about 16% while in the limbs it remained roughly the same. The largest third and fifth harmonic components of flux density occured in the central limb. Their magnitudes were 7% and 4.9% of the fundamental components respectively at a core excitation of 1.7 Tesla. In the yokes the harmonic contents were of much smaller magnitudes.