# High voltage lines

#### salsero

What is commonly the voltage in the high voltage lines used to transport electric energy over large distances? What is their resistance and inductance? What is the magnitude of the current flowing there?

Yevgeny.

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#### chroot

Staff Emeritus
Gold Member
I believe the range 30 to 750 kilovolts is relatively common. I'm not quite sure of the current in most lines, but I'd expect a 50-100 amps or so for most transmission lines. Don't quote me on this!

- Warren

#### DeCoY

The Powerstation genarates 11-15kV at 50hz then it is stepped up to 400kV using transformers for the supergrid because more voltage = less current which means u dont need as big wires to carry the current long distences,then it is stepped down to 33k for industry, and then stepped down to 240V for towns and villages.

I hope that helps mate...
I even signed up to the forum just to help u out :)

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#### flexifirm

60Hz

But that's 60Hz in North America

#### russ_watters

Mentor
Re: 60Hz

Originally posted by flexifirm
But that's 60Hz in North America
And 500kV. Distribution is more complicated. You can have 13.2kV or 4160V, and at the point of use, you can have 120V, 208V, 240V, 277V, 460V, and single or three phase.

#### dlgoff

Gold Member
For transmission lines, I've seen 115kV, 230kV, and 345kV (phase to phase voltages).

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#### Sudden_strike88

Hello, Im new to this forum and this is my first post.
I am an electrician in the making so to speak, and I think I can explain a bit here.

The most common voltage of a generator (lets say a dam, 50MW) is about 13kV. Then depending on the distance of the energy beeng transported it is stepped up by a substation from anywhere like 200kV to 700kv or so. Experimental power lines in Siberia run on a relatively very high 1 megavolt (1000Kv).
The previous post that says that the main purpose of high voltage are thinner lines is not exactly it. Of cource companies want to save metal and money, but low currents result in lower losses. It is not unisual that many hundreds or thousands of kilowatts are lost in the power lines by the capacitive effect of the lines either hanging or as a cable buried in the ground. That is why high-voltage lines usually revolve (like a 4-twisted pair for a computer. A LAN cable in other words) to reduce the capacitive efect.
Tu usual inner-city distribution the common voltage ratings do not exceed 22kV if I recall, very commonly cables.
The it can be used directly by a large industry or transformed down to as low as 670 Volts (I`m talking about European systems) because that is the lowest "high voltage", a standard.
Households today can recieve a 400V 3-pole TN or TN-C-S net that uses the PEN (Protective Earth & Neutral, yellow-green-blue) is split in a TN-C system where they use one plase an the N (zero point of either a Y or D transformer) point to get 2x1/3 of 400 wich is 230! A brilliant system, however the second earth error is extremely high...
Then again older households use IT systems usually, rarely TT. Those are usual D-transformer 230V systems that can eithe use 2 or 3 phases wich both deliver 230V.
Usually you can find out what net you have by asking your electrical company.

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