Influence of the mix 60° - 23° in different layers of T-joint of 3phase transformer core on longitudinal direction of flux distribution

This paper describes the result of investigation of longitudinal direction of flux distribution in 100kVA 3phase distribution transformer assembled with the mix 60° - 23° in different layers of T-joint. The measurement involves the fundamental and third harmonic of the easy and hard direction of flux density at each location measurement. The flux distributions have been measured using no load test by arrays of search coil in M5 (CGO) grades material of transformer core laminations. The localised flux density at the outer the mix 60° -23° in different layers of T-joint is 1.4T and rises to be 1.7T at the inner edges of the mix60° - 23° in different layers of T-joint when the transformer core energized 1.5 T 50Hz. Harmonic occurs mostly in the T-joint where local regions are saturated and the flux deviates from the rolling direction. A small amount of flux deviation from the rolling direction occurs at the overlap, but no rotational flux is present in the joint.