Transmission Tower Design|Electrical Tower Design

Transmission tower design: Electrical Tower is modeled using constant parameters such as height, bracing system, angle sections, base widths, wind zone, common clearances, span, conductor and ground wire specifications.The loads are calculated using IS: 802(1995)

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Transmission tower design

The Transmission line towers are one of the important life line structures in the distribution of power from the source to the various places for several purposes. The tower is designed for the wind zone V carrying 132 KV DC.

Types of Towers

The types of towers based on their constructional features, which are in use on the power transmission lines are
given below.
 Self-Supporting Towers
 Conventional Guyed Towers
 Chainette Guyed Towers

Self-Supporting Towers:

Self-supporting towers are covered under Indian Standard (IS: 802) and other National
and International Standards.

These fabricated, using tested quality mild steel structural‟s or a combination of tested
quality mild steel and High tensile structural‟s conforming to IS: 2062 and IS:8500 respectively.

Conventional Guyed Towers

Conventional Guyed Towers are the towers comprise portal structures fabricated in „Y‟ and „V‟ shapes and have been used in some of the countries for EHV transmission lines up to 735 kV.

The guys may be internal or external.
The guyed tower including guy anchors occupy much larger land as compared to selfsupporting towers and as such .This type of construction finds application in long unoccupied, waste land.

Chainette Guyed Tower

Chainette Guyed Tower is similar to that of guyed towers but carrying double circuit lines.

Tower design

Tower width
Base width
Top damper width
Cross arms length

Height of Tower Structure

Height of tower “H” ts determined by;

H =h₁+h₂+h₃+h₄

h₁=Minimum permissible ground clearance
h₂=Maximum sag
h₃=Vertical spacing between conductors
h₄ =Vertical clearance between earthwire and top conductor

base width design

The base width(at the concrete level) is the distance between the centre of gravity at one corner leg and
the centre of gravity of the adjacent corner leg.
A particular base width which gives the minimum total cost of the fower and foundations.
Ryle formula

The ratio of base width to total tower height for most towers is generally about one-fifth to one-tenth.

Ground Clearance of Tower

Ground clearance,

transmission-tower-min-permissible-clearance-formula

Minimum permissible clearance

transmission tower minimum permissible clearance as per IE Rule 1956, rule 77(4)

transmission-tower-min-permissible-clearance

CONDUCTOR

A substance or a material which allows the electric current to pass through its body when it is subjected to a difference of electric potential is known as Conductor.

The materials which are used as conductors for over head transmission lines should have the following electrical and physical properties.

It should have a high conductivity
It should have tensile strength.
It should have a high melting point and thermal stability.
It should be flexible to permit us to handle easily and to transport to the site easily.
It should be corrosion resistance.