What is Electric Pole and Tower?

Pole and tower aren’t the same things. But do we know what is electric pole and tower? We mistake by thinking they are the same. They have a lot of differences. Let’s talk about what is electric pole and tower?

What is Electric Pole and Tower and Difference between them

Poles

1. Generally, poles are made of wood/steel or concrete.
2. Poles are light weighted and cheap.
3. They are used for supplying low voltage up to 11 kV.
4. It has small span length.
5. It is used for supply system and distribution in small distance. 
6. Pole is not lasting.
7. It is weak to carry machinery weight.
8. Maintenance cost is not expensive. Less chance of accidents.

Towers

1. The tower is usually made off steel channel and angle.
2. The tower is heavy and making cost is more than pole.
3. The tower is used for supplying high voltage.
4. It has a long span of length.
5. The tower is used for supplying voltage in long distances. 
6. It has enough power to carry machinery weight. 
7. Maintenance cost is expensive and danger is high.

Measuring the height of the Pole and tower, there are 6 factors for measuring the height from the ground

Line Voltage

Phase to phase voltage in a three-phase system is line voltage. Usually, the line voltage is one of the factors while construction of pole and tower.

Size and Weight of Wire

We know from the relation of power, voltage, and current, 

P= IV

It means, the more Transmission volt, the less is the size of the supply wire. Which is financially good. It will decrease system loss and the voltage regulation will be high. But it will increase the Insulator size, tower’s height. So we have to keep these things in mind. 

Distance of Lowest Wire from The Ground

While setting the pole/tower there must be a minimum distance of the wire with the ground. Generally, this distance is 15-20 feet.

Distance between Highest and Lowest Wire

It is necessary to have a minimum distance between both conductors of the pole. otherwise, the chances of the corona, humming effect increase.

Sag of Wire

Sag means hanging. Now, who will be hanging? If you notice you will see the wires of transformers are a bit hanging. Imagine two dots on two points of the wire. Now draw a straight line between them. The part below the straight line is the sag of the wire.

What is the Problem of More or Less Sag?

Towers Cross-arm to cross-arm should be at a certain level. If the sag is more the distance will vary from wires. And if the spacing is not right there will be sparking by air polarizing and there will be corona loss.

How Can I keep Sag at a Certain Level? 

By using a vibration damper. You will see some clippers on the transmission line. It is for preventing the increase of sag. The distance of the highest point of the tower and highest cross-arm.

Distance between Towers Highest Point and Highest Cross-Arm

The distance should be at a minimum level which should not be more than 15-20 centimeters. 

Insulator Size

The size depends on the transmission/ distribution line. The more is the transmission volt the more is the insulator size. Pin type and shackle type insulator are used for poles and strain/suspension type insulator is used for towers.

That’s all for today’s article ‘what is electric pole and tower?’

Hope now you know what is electric poles, wood utility poles, and towers. If you have any queries, feel free to ask in the comment section.

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