# The Naked Scientists Forum

### Author Topic: How is electricity transmitted by power lines?  (Read 2960 times)

#### Simulated

• Neilep Level Member
• Posts: 7188
• Thanked: 1 times
• Simulated..What more do you needa know :P
##### How is electricity transmitted by power lines?
« on: 03/03/2008 00:03:30 »

See that picture? Of course you do unless your Dan at work, but anyways how far are most telephone/power line poles away from eachother?

And in that one. You've got one Big Power Pole, One Smaller, and the normal ones. Can anyone give me a logical reason why they have three power things that close together? And how much power does the big one, middle sized, and the smallest one carry?

thanks
« Last Edit: 04/03/2008 23:15:00 by chris »

#### Pumblechook

• Hero Member
• Posts: 569
##### Re: How is electricity transmitted by power lines?
« Reply #1 on: 03/03/2008 00:49:28 »
The pylons are at 400, 275 or 132,000 Volts..  This is for long distance transmission.  This has to be stepped down to 33,000 Volts (larger poles) for more local distribution and then to 11,000 Volts (smaller poles) for more local still and then down to 400/230 Volt on smaller poles or across the walls of buildings or underground to houses and other buildings.  It is bit like arteries, veins and capilaries all intermingled.  These are British voltages.

#### lyner

• Guest
##### Re: How is electricity transmitted by power lines?
« Reply #2 on: 04/03/2008 10:08:04 »
The reason for using such high voltages is that a higher voltage involves a smaller current. There is power loss when the current passes through the resistance of supply lines so - higher volts, lower current, lower loss.
High voltage lines are expensive and substations with their step down transformers are expensive.
In general, a very high voltage line will probably feed a major city or area where  the extra cost will return a cost saving by reducing power loss. Smaller communities are fed with  lower voltages to fit the economics of the situation. Basically, you couldn't afford to have a single high voltage network and direct stepping down for every row of houses. (Plus .you wouldn't see the sky for pylons)

#### Simulated

• Neilep Level Member
• Posts: 7188
• Thanked: 1 times
• Simulated..What more do you needa know :P
##### Re: How is electricity transmitted by power lines?
« Reply #3 on: 04/03/2008 20:22:32 »
Thanks for the information you two.

#### Simulated

• Neilep Level Member
• Posts: 7188
• Thanked: 1 times
• Simulated..What more do you needa know :P
##### How is electricity transmitted by power lines?
« Reply #4 on: 05/03/2008 00:51:39 »
How about how far are the two poles in the first picture normally spaced apart? That'd be nice to know how far so I can get a ruff idea on how far 100 m and 200 m sprints are..

#### MayoFlyFarmer

• Hero Member
• Posts: 863
##### How is electricity transmitted by power lines?
« Reply #5 on: 05/03/2008 22:23:12 »
if i had to guess by looking @ the picture, i'd say ~150m.  but i don't think that this is a standardized distance.

#### The Naked Scientists Forum

##### How is electricity transmitted by power lines?
« Reply #5 on: 05/03/2008 22:23:12 »