Question

Problem 3: A three-phase, 60 Hz transmission line is built with an ACSR conductor. The conductor diameter is 0.68 inch, GMR = 0.023 ft., and AC resistance of 0.342 /mile at 50°C. The conductors are laterally spaced with D= 1.7 m between conductor centers. The line is 50 km long and supplies a 5 MW load. The line to line load voltage is 13.2 kV. [40 points] (a) Find the total impedance of the line. (b) Determine the sending-end voltage, current, real power, and reactive power for the load with a PF of 0.85 lagging. (C) Plot the sending-end voltage versus the length of the transmission line varying between 1 to 50 km. (d) Assuming the line being 50 km long supplying a variable load of 100 kW to 2 MW, calculate the voltage regulation and plot against the load. At what load, you expect 5% VR?

Answer 1

L = 10 In GMD 277 00701 27" GMR GMD= V(1.7)(1.7)(1.7) = 1.7m GMR = .023ft = .0070104m L = 40 x In 1 = 2 x 10-7 x 5.491 = 10.98 x 10-7H/m R= 3422/mile = .21252/Km SO Rline = .2125 x 50 = 10.62 Lline = 10.982 x 10-7 x 50 x 103 = 54.91m H Xline = j x 27 x 60 x 54.91 x 10-3 = 120.722 Zline = 10.6 + 120.7 12