Types Of Transmission Towers|Electrical Tower Types

In this post, you will learn the different types of Electrical transmission Towers in detail. You can also read about What is an Electrical transmission tower and parts of an Electric Tower, transmission line, and the different types of Transmission structure also.

Contents

Electrical Transmission Towers

Transmission towers/ Electric towers support the high-voltage conductors of overhead power lines, from the generating station to the source substations and satellite substations located near populated areas.

Read: Parts of a Power transmission line and Transmission tower|Transmission tower parts

Types of Electrical Transmission Towers

Based on different criteria there and different types of transmission towers.

based on the angle of deviation
based on the force applied by the conductor on the cross arms
Based on the number of circuits carried by a transmission tower
Based on Structure types
based on the material used
current types of towers
current caring capacity in kV

Electrical tower types based on the angle of deviation

Based on the angle of deviation, there are four types of transmission towers

A-type tower ( 0^o to 2^o)
B type tower (2^o to 15^o)
C type tower (15° to 30°)
D type tower (30° to 60^o)
E type tower (60^o to 90^o)

a) A-type tower

The angle of deviation is 0^o to 2^o for A-type towers. The type A Tower is a Tangent Tower with suspension string. it is used on straight runs and up to 2° line diversion.

b) B – type tower

The angle of deviation is 2^o to 15^o for B-type towers. Type B Tower is a Small Angle Tower with tension string it is used for line deviation from 2° to 15°.

c) C – type tower

The angle of deviation is 15^o to 30^o for C-type towers. Type C Tower is a Medium Angle Tower with tension string. it is used for line deviation from 15° to 30°.

d) D – type tower

The angle of deviation is 30^o to 60^o for D-type towers. Type D Tower is a Large angle tower with tension string. it is used for line deviation from 30° to 60^o.

e) E – type tower

The angle of deviation is 60^o to 90^o for E-type towers. Type E Tower is a Dead End Tower with tension string. it is used for line termination & starting

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Electrical tower types that based on, the force applied by the conductor on the cross arms

As per the force applied by the conductor on the cross arms, the transmission towers can be categorized as ;

Tangent suspension tower
Angle tower or tension tower or Section tower
special type tower

Tangent suspension tower

it is generally A – type tower.

Angle tower or tension tower

or tension tower or sometimes it is called section tower. All B, C and D types of transmission towers come under this category.

special type tower

Apart from the above-customized type of tower, this type of tower is designed to meet special usages listed below:

a) River crossing tower :

b) Railway/ Highway crossing tower:

c) Transposition tower:

Electrical tower types based on the number of circuits

Based on the number of circuits carried by a transmission tower, it can be classified as
a) Single circuit tower
b) Double circuit tower
c) Multi – circuit tower

Single circuit tower

Double circuit tower

Multi – circuit tower

Electrical tower types based on the Structure types

Based on the Structure types of a transmission tower, it can be classified as

a) Lattice Structure
b) Hybrid Structure
c) Tubular Pole Structure

Electrical tower types based on the material used

Classification is forming the point of view of material used, it can be classified as-

a) Steel Structure
b) Wooden Material
c) RCC Pole

The supports for an overhead line must be capable of carrying the load due to Conductors,Insulators and Wind load on the support itself.

Steel Structure

Steel tubular poles & steel towers

Steel tubular poles: Stepped pole manufactured from a single tube , the diameter being reduced in parallel steps. these are more costly than RCC and wooden poles.
Steel tubular poles are light weight , have high strength to weight ratio and long life.
Steel tubular poles are used for lines upto 33kV

Steel towers: these are used for lines of 66kKV and above. Steel towers have very long life and a high degree of reliability. Steel towers can withstand very severe weather conditions.
Overhead HV, EHV, and UHV use self-supporting steel towers.

Wooden Poles tower

Wooden Poles are made of chemically treated wood.

these are used for distribution Fines, especially in areas where good quality wood are
available.
Wooden Poles towers are very economical but susceptible to decay.
To protect from decay, the poles have zinc or aluminum cap at the top and bottom

RCC Poles

RCC Pole towers are made of reinforced concrete cement.
RCC Poles are stronger than wooden poles but more costly.
RCC towers are having a very long life and need little maintenance.
But RCC Poles are bulky and heavy.
RCC Poles are widely used for distribution lines up to 33kV.
also, RCC Poles can be manufactured at sites.

Electrical tower types based on the current types

On the basis of current types of towers

a) HVAC transmission tower

b) HVDC transmission tower

c) Railway traction line tower

HVAC transmission tower

Three phase electric power systems are used for high voltage (66 or 69 kV and above) and extra-high voltage (110 or 115 kV and above; most often 138 or 230 kV and above in contemporary systems) AC transmission lines.

The towers must be designed to carry three(or multiples of three) conductors.

The towers are usually steel lattices or trusses (wooden structures are used in some cases) and the insulators are either glass or porcelain discs.

HVDC transmission tower

HVDC transmission lines are either monopolar or bipolar systems.

With bipolar systems, the conductor arrangement with one conductor on each side of the tower is used.

For single-pole HVDC transmission with ground return, towers with only one conductor can be used.

The towers are designed for later conversion to a two-pole system.

In these cases, often conductors n both sides of the tower are installed for mechanical reasons.

Railway traction line tower

in Railway traction, transmission lines are similar in construction to those towers used for 110 kV-three phase lines.

Steel tube or concrete poles are also often used for these lines.

The towers of railway traction lines carry two electric circuits, so they have four conductors.

Each circuit occupies one half of the cross arm. For six electric circuits arrangement of the conductors Is in three levels.

Electrical tower types based on the current carrying capacity in kV

On the basis of the current carrying capacity in kV, Transmission towers can be classified as,

a) 11 kV, b) 33 kV c) 66 kV d) 110 kV e) 132 kV f) 220 kV g) 400 kV h) 500 kV i) 765 kV j) 800 kV k) 1200 kV

Types of Transmission Towers|Electrical Tower Types