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Question 1 Harmonics in Power Systems [11] a 1D v_ ff) an ideal J0 SOUTCE nonlinear loads Vy (D Fig. 1 Harmonic currents in 3-phase four-wire network circuit 1.1 Clearly describe two problems that can be caused by harmonic currents in Fig. 1 (4). 1.2. +A balanced nonlinear load in Fig. 1 produces line currents containing fundamental and 20% third harmonic: ian(t) = 11 cos (w t 6 1) + 0.2 |: cos (3w t 6 3). Find the rms neutral current and compare its amplitude to the rms line current amplitude. (7) Question 2 DC Motor Drives [24] 2.1 Draw an open-loop control block diagram of a separately excited DC motor (3) 2.2 From your answer in Question 2.1, develop the transfer function (TF) (10) 2.3 Approximate TF if the armature inductance of the motor very small (3) 2.4 Approximate the TF when the friction coefficient B is smaller and can therefore be neglected (3). 2.5 State five (5) advantages of a closed loop speed control