conversion of voltage

[ITlover]

Different countries have different standard of voltage . Some countries especially Arab and Western Countries use 110v but other countries like India and Pakistan use 220v.

I want to know why different countries use different voltages?

any specific reason

Regards,

[glc]

Why do some countries drive on the right side of the road, and some on the left side?

[TwoRails]

It's just what their engineers designed at the time.

[Byte 2.0]

Since this is on eletric, actually what people call 110 is actually 120 and the same for 220, is really 240.

I am not certain for the reason why some places choose to use 240 over 120. 240 certainly has enough power to run anything someone would use in their homes, where as places that are on the 120 standard use 2 pairs and make a 240 circuit where needed such as for Ovens.

To me it seems more effeicent to use 120, and only bump it up to 240 when needed.
I don't know about you, but I think 240 for a light bulb is overkill.

[doctorgonzo]

Why does PAL and NTSC TV exist? Why DVD-R and DVD+R? Why Beta and VHS? Why is our electricity even AC and not DC? (An interesting aside, Thomas Edison held the patents for many DC devices and so he pushed hard for the electric grid to be all DC. He even created the electric chair to prove how dangerous AC current can be!)

A lot of these standards came about as much due to politics and luck as due to some good scientific reason. This article (http://www.straightdope.com/classics/a3_292.html) says that the U.S. used 120 volts because anything higher would blow up the light bulbs manufactured at the time, but that doesn't explain why it is 120, and not 115, 103.4, or anything like that.

[Byte 2.0]

Doctorgonzo is right on that.

Nikola Tesla believed strongly in AC, but got a job working for Thomas Edison, after Nikola Tesla improved the DC generators and Thomas Edison screwed him over on the deal, Nikola Tesla went and worked for Westinghouse Electric Company on AC, which he loved.


Nikola Tesla was a man before his time, to bad much of his life is a mystery and wrapped in myths.

[edfair]

Engineers make the tradeoff based on economic issues. The primary concern is "how much distribution at low voltage".

If I recall correctly from my design days almost 50 years ago the specifications for low voltage alternating current was 117vac. Commonly referred to as either 110 or 120 the designers at the time referred to it as 120 or if centertapped delta or single phase connection 120/240.

Using 240 as a current source allows smaller wires than 120 to carry the same energy.

[roomwithamoose]

Doctorgonzo is right on that.

Nikola Tesla believed strongly in AC, but got a job working for Thomas Edison, after Nikola Tesla improved the DC generators and Thomas Edison screwed him over on the deal, Nikola Tesla went and worked for Westinghouse Electric Company on AC, which he loved.


Nikola Tesla was a man before his time, to bad much of his life is a mystery and wrapped in myths.
I strongly agree. If we had a man of Telsa's brilliance today, I believe we would already be on Mars.

I had be taught that other countries were using 240vac because it allowed you to send more power farther withour transformers. And I also believe that edfair is correct about the same lines being able to carry more power. Out of curiosity, what other countries use 120VAC other than the US?

But it is the same question as why is the US not using the metric system?

[mattg2k4]

At my house in my room it is neither 110 nor 120, it was 115.6V the last time I measured it :p

I wonder if the difference between 240 and 120 in the house would make a big difference in efficiency? It does definitely mean you can use thinner wires for the same current in house wiring, but on the same hand the insulation is thicker, and modern electronics, which usually runs at low voltages has to work a bit more to step the voltage down.

You can also ask why power in the US is at 60Hz, while some places run at 50Hz, or possibly even more different.

[doctorgonzo]

Here (http://en.wikipedia.org/wiki/List_of_countries_with_mains_power_plugs%2C_voltages_%26_frequencies) is a list of mains voltages and frequencies for different countries.

For long-distance transmission, higher voltage is better than higher current, so that's why the long-distance lines carry hundreds of thousands of volts. That is stepped down at various stops along the way before it gets to your house.