Chapter 7, Problem 7.52P

Your objective is to obtain a Th´evenin equivalent for thecircuit shown in Fig. P7.46, given that is(t) = 3cos 4×104t A. Tothat end:(a) Transform the circuit to the phasor domain.(b) Apply the source-transformation technique to obtain theTh´evenin equivalent circuit at terminals (a,b).  (c) Transform the phasor-domain Th´evenin circuit back to thetime domain.

7.48 Determine the Thévenin equivalent of the circuit in Fig. P7.48 at terminals (a,b), given that Us(t) 12 cos 2500t V, = is(t)=0.5 cos (2500t - 30°) A.

Power system studies on an existing system have indicated that 2400 MW are to be transmitted for a distance of 400 Km. The voltage levels being considered include 345 kV, 500 kV, and 765 kV. For a preliminary design based on the practical line loadability, you may assume the following surge impedances 345 kV Zc=320 2 500 kV Zc=290 765 kV Zc=265 The line wavelength may be assumed to be 5000 km. The practical line loadability may be based on a load angle of 35º. Assume |Vs| = 1.0 pu and |Vr|=0.9 pu. a) Determine the number of three-phase transmission circuits required for each voltage level. Each transmission tower may have up to two circuits. To limit the corona loss, all 500-kV lines must have at least two conductors per phase, and all 765-kV lines must have at least four conductors per phase. b) The bundle spacing is 45 cm. The conductor size should be such that the line would be capable of carrying current corresponding to at least 5000 MVA. Determine the number of conductors in the…