ABSTRACT
Draw the graph of current i against θ and analyse the current into its first three constituent components, each coefficient correct to 2 decimal places. (30)
5. The cross-sectional area of a transformer limb is 8000mm2 and the volume of the transformer core is 4× 106 mm3. Themaximum value of the core flux is 12mWb at a frequency of 50Hz. Taking the Steinmetz index as 1.6, the hysteresis loss is found to be 80W. Determine the value of the hysteresis loss when the maximum core flux is 9mWb and the frequency is 50Hz. (6)
6. The core of an inductor has a hysteresis loss of 25Wand an eddy current loss of 15W when operating at 50Hz frequency. Determine (a) the values of the losses if the frequency is increased to 70Hz, and (b) the total core loss if the frequency is 50Hz and the laminations are made three quarters of their original thickness.Assume that the flux density remains unchanged in each case.
