Different clamp stress impact on losses and flux distribution between two of 3 phase distribution transformer 1000 kVA assembled with stagger yoke of transformer core lamination

The power loss of transformer core are depends on a large extent on mechanical stress. This paper describes the result of an investigation on effect different clamp stress of core lamination in the two of 3 phase distribution transformer 1000 kVA assembled with 45 degree corner joint and 90 degree T-joint. The investigation involves the variation of power loss, building factor, the total harmonic distortion of flux and flux leakages. The power loss and flux distribution have been measured using no load test in two types of model of setting of core built from the same size and type of M5 (CGO) grades material of laminations. The loss of the transformer core assembled with 24 Nm clamping stress of core lamination is 3% better than the loss of the transformer core assembled with 12 Nm clamping stress of core lamination over the whole flux density range, 50 Hz. The flux leakage at the corner joint in the core assembled with 24 Nm clamping stress of core lamination is lower than the other two of the transformer cores, over the whole flux density range. The total harmonic distortion of flux is smaller in the transformer core assembled with 24 Nm clamping stress of core lamination and is larger in the transformer core assembled with 12 Nm clamping stress of core lamination. Using 24 Nm clamping stress of core lamination in transformer core is more efficient than using the other two types of clamping stress of transformer core lamination.