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Preview

Three-Phase line inductance

Symmetrical spacing

Asymmetrical spacing

Transposition

http://upload.wikimedia.org/wikipedia/commons/d/d9/Facility4508_Pylon206.JPG

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Composite condutor

an

n

am

m

ac

c

ab

baa

nmcba

DI

DI

DI

DI

rI

IIIII

1ln

1ln

1ln

1ln

'

1ln102

0

7

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

Similarly,

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

n strands that are electrically parallel:

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

Substituting the values ofLa,Lb etc.

Where,

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Composite Conductors

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

Where,

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Bundled Conductors

Extra high voltage lines corona causes problems such as

power loss, interference, etc.

The high voltage surface gradient is reduced considerablyby having two or more conductors.

It also reduces the inductance of lines by reducing voltage

drop.

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

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Bundled Conductors

where n=2,3 ....

Where,Ds is the GMR of the conductor

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Line Parameters Preview

Resistance

Inductance

Inductance of single conductor

Inductance of three-phase line (symmetrical, asymmetrical

spacing, transposition)

Composite and bundled conductor

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Capacitance of a Straight Conductor

Capacitance in a transmission line results due to the potentialdifference between the conductors.

The conductors get charged in the same way as the parallel

plates of a capacitor.

Capacitance between two parallel conductors depends on the

size and the spacing between the conductors.

Usually the capacitance is neglected for the transmission lines

that are less than 80 km (50 miles) long.

However the capacitance becomes significant for longer lines

with higher voltage.

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Capacitance of a Straight Conductor

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Capacitance of a Straight Conductor

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Capacitance of a Single-Phase Line

Let us assume that conductor 1 carriesa charge ofq1C/m while conductor 2

carries a charge q2 C/m.

D>> r1 and r2 and ground influence

also is neglected.

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Capacitance of a Single-Phase Line

Let principle of superposition

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Assume that q1 (= -q2 ) is equal to q

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Capacitance of a Single-Phase Line

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/ui/Course_home-1.htm

Assuming r1 = r2= r

Capacitance is defined between the

conductor and neutral