Transformer Core Building Factor: From Sheet Loss to Core Loss

Certificate specific loss times core mass is only a starting point. Sheet tests do not reproduce production joints and assembled clamping. At corners, flux crosses gaps and transfers between laminations. At a three-phase T-joint, its direction changes. Cutting and clamping also change the stress state. A building factor connects material performance to the finished core. The article gives about one point one to one point three for three-phase step-lap cores, depending on design and manufacture. It is not a universal constant. Compare quotations using material grade, thickness, the named loss-test method, and the building factor with its basis. Then compare calculated loss at the design flux density.