Question #1 (10 Marks)
Semester 2 Further and Deferred, 2024
ELEN6009-X Power System Analysis
A three-phase transposed line consists of one conductor per phase with a flat horizontal
spacing of 11 m as shown in Figure 1(a). Each conductor has a diameter of 3.625 cm and a
GMR of 1.439 cm.
The line is to be replaced by a three-conductor bundle per phase. Each conductor in the
bundle has a diameter of 2.1793 cm and a GMR of 0.8839 cm. The new line will also have a
flat horizontal configuration, but it is to be operated at a higher voltage and therefore the
phase spacing is increased to 14 m measured from the centres of the bundles as shown in
Figure 1(b). The spacing between the conductors in the bundle is 45 cm. Determine:
(a) The GMD for the three phase configurations in Figures 1(a) and (b).
(2 marks)
(b) The overall GMR (for inductance and capacitance calculations) for the three-phase
configuration in Figure 1(b).
(2 marks)
(c) The inductance (in mH/km) and capacitance (in µF/km) for the three-phase
configuration in Figure 1(a).
(2 marks)
(d) The inductance (in mH/km) and capacitance (in µF/km) for the three-phase
configuration in Figure 1(b).
(2 marks)
(e) The percentage change in the inductance and capacitance of the two configurations.
(2 marks)
$\mu_0 = 4\pi \times 10^{-7} H/m$ and $\epsilon_0 = 8.85 \times 10^{-12} F/m$