Three identical coils, each of N turns and area A, are fixed on the same rotating axle and are spaced 120∘ apart around the axis. The axle rotates with constant angular speed in a uniform magnetic field, producing a balanced three-phase supply.
(a) If the instantaneous emf in the first coil is Emsinωt, write the expressions for the instantaneous emfs in the second and third coils.
(b) Prove that the algebraic sum of the three instantaneous emfs is zero at every instant.
(c) The peak value of the emf in each phase is 300V. Calculate the rms value of the line voltage measured between the terminals of any two phases.