Question

15 marks] B. A toroidal core with a mean diameter of 200 mm and a cross-sectional area of 800 mm has an air gap of length 1.1 mm cut in it Fringing and leakage of flux around the air gap may be neglected (i) Determine the current required in a coil of 1100 turns to produce a flux density of 1 T The relative permeability , of the core material (iron) may be assumed to be 3000 for this level of flux density. Permeability μ-AGM , μοΑπ x 10-7Hm]. 15 marks (ii) The above coil is the primary of a single-phase ideal transformer. The AC supply voltage to the primary winding is sinusoidal at 50 Hz. What is the highest RMS AC supply voltage that can be applied to the coil, so that the maximum flux density in the core does not exceed 1 T? 15 marks] (iii) If the RMS value of the available 50 Hz AC supply voltage is twice the value found in (ii), what change(s) must be made to the coil (without changing any dimension of the core) so that the maximum flux density remains the same as 1 T? 12 marks]

Answer 1

Mmf จุ2-9 mmf 929-ל (四