POWER SYSTEMS
EE408/EE419
TRANSMISSION LINES
MS. KALAISELVI ARAMUGAM
kalaiselvi@ucsiuniversity.edu.my
GMR
Example 3.1
Calculate the geometric mean radius of a conductor in
terms of the radius r of an individual strand as shown in
Figure for
(a)Three equal strands
(b)Four equal strands
EE408/EE419 - POWER SYSTEMS
L3-TRANSMISSION LINES
2
INDUCTANCE OF THREE PHASE
DOUBLE CIRCUIT LINES
Example 3.2
One circuit of a single-phase transmission line is composed of
three solid 0.5 cm radius wires. The return circuit is composed of
two solid 2.5 cm radius wires. The arrangement of conductors is
as shown in Figure below. Applying the concept of the GMD and
GMR, determine the inductance of the complete line in mH/km.
5m
5m
1
2
EE408/EE419 - POWER SYSTEMS
5m
10 m
3
1’
L3-TRANSMISSION LINES
2’
3
INDUCTANCE AND CAPACITANCE
PER PHASE
Example 3.3
A 400 kV, 3-phase bundled conductor line with two subconductors per phase has a horizontal configuration as shown in
Figure. The radius of each sub-conductor is 1.6 cm. Calculate the
inductance per phase per km of the line.
EE408/EE419 - POWER SYSTEMS
L3-TRANSMISSION LINES
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INDUCTANCE AND CAPACITANCE
PER PHASE
Example 3.4
A single-circuit three-phase transmission transposed line is
composed of four ACSR 1,272,000 cmil conductor per phase with
horizontal configuration as shown in Figure. The bundle spacing
is 45 cm, given GMR (L) and diameter (C) are 1.4173 cm and
3.5103 cm respectively. Determine the inductance and
capacitance per phase per km of the line.
EE408/EE419 - POWER SYSTEMS
L3-TRANSMISSION LINES
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MEDIUM TRANSMISSION LINE
Example 3.5
A 200 km long 3-phase overhead line has a resistance
of 48.7 Ω per phase, inductive reactance of 80.20 Ω per
phase and capacitance 8.42 nF per phase/km. It
supplies a load of 13.5 MW at a voltage of 88 kV and
power factor 0.9 lagging. Use nominal pi circuit,
calculate the sending end voltage, current, voltage
regulation and power angle.
EE408/EE419 - POWER SYSTEMS
L3-TRANSMISSION LINES
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LONG TRANSMISSION LINE
Example 3.6
A 3-phase 300 km long line has a total series
impedance of 200∟80° ohms per phase and a total
shunt admittance of 0.0013∟90° siemens per phase to
neutral. The receiving end voltage is 220 kV. The line
supplies 60 MW at 0.8 power factor lagging. Calculate
the sending end voltage and current.
EE408/EE419 - POWER SYSTEMS
L3-TRANSMISSION LINES
7