The main factor of any electrical power transmission line is transmission tower. The Main parameters of high voltage transmission lines are mainly depend on voltage level. There are different types of towers use for electrical power transmission lines. The major types of Transmission towers can categorize as bellow.
1. Suspension Tower
2. Tension Tower
3. Transposition Tower
4. Special Tower
Following are the types of transmission tower types which are widely used by considering the technical background. These transmission types are mainly classified according to its unique features and different applications on electrical power transmission. Transmission line tower designers have been endeavouring to develop tower with such shapes wich blend with the environment. Normally the tower shapes are being used with conservation environmental attraction .The highest attention and the pubic become more and more conscious of the detrimental effects to transmission line towers on the land.
Mainly the Suspension towers are on the way of that straight line of transmission line . It may also vary maximum to degree of 5 angle . The high voltage suspension towers are design to carry the only weight of the conductor in straight line position.Most of towers in any transmission line is fall into this type of tower category and construction cost of suspension type transmission lines are much cheaper compare to other types of transmission lines.These type of towers are used on the lines for straight run or for small angle of deviation up to 2° or 5° . Conductor on suspension towers may be supported by means of I-string, V- string or the combination of I & V strings.
Tension Towers (Angle)
Electrical Tension towers are used at locations where the angel of deviation is more than degree of 5. These towers are also known as angle towers and the tower are designed to take the tension load of the cable. Tension towers are mostly use for turning points and for the section isolate locations.
The piece of line from one angle tower to other angle tower is known as section and length of the section may vary and depend on the geographical location. All the towers in between the section is suspension towers. Suspension towers are lightweight and much economical compare to angle towers.
Tension tower can further divide in to two categories and these tower type are also can be categorized according to deviation angle in location of appropriate towers. The types of tension towers due to angle of vary are mentioned in bellow.
0-10 degree tension towers (TD1)
10- 30 degree tension towers (TD3)
30-60 degree tension towers (TD6)
These towers are used at locations such as those involving long-span river crossings, valley crossings, power line crossings from above existing lines, power lines crossings bellow existing lines (Gantry type structures) , tapping to existing lines, special termination towers etc.
The cost for special tower is much higher than suspension tower line costs. The design of special tower are much based on the location.
Special Towers are widely used for tapping existing lines, Special termination towers and falling on the line route.
Body extension and leg extension
If we consider on the height of transmission tower , height of all towers in same transmission line are not same.
Differnt type of tower hieght can find out by using transmission tower body extension and leg extension . Span between towers are not same in everywhere in same high voltage transmission line due to different geographical location.
There are so many design parameters we have to consider while we are laying a transmission line in certain area. We are plan to discuss more of these parameters on our future articles.