Why AC current is used in power lines not the DC ?

Question

why AC is an electricity source not the DC,
also if u can tell me where i could find more information about this subject .

Answer 1

In the beginning, there were two ways of doing things: direct current sources and alternating current sources. The good things about DC are that it is infinitely adjustable from a speed persepctive (independent of frequency, basically), and that for most applications current and torque are pretty much a linear relation. For AC, you can get more standardization on speeds (because it IS tied directly to frequency), and the ability to step up / step down voltage for transmission is far easier.

Both systems deliver power equally; power is, by definition, a volt-amp ... wherein one volt-amp = one volt * one amp.

Losses in transmission are directly related to the current flowing in the lines; thus transmitting at a higher voltage (and therefore lower current) will produce lower losses. With transformers, it is fairly easy to change AC voltages to suit transmission requirements - with DC, the upper voltage is often limited by the mechanical interaction between the brush and commutator surface.

Investigating Thomas Edison, Nikolai Tesla, Power Systems, Power Transmission, and Power Generation should give you lots of background into why AC is so predominant today.

Answer 2

Look up AC theory or Tesla theory. AC is used because there are less losses in the line, compared to DC, and you can easily step up or step down your voltages with the use of a transformer.
With the voltage being positive for an equal amount of time that it is negative, your average voltage is zero, thus there are no losses at the line.

Answer 3

AC's voltage and current can be change while retaining the same power by means of a transformer.

While it's voltage is stepped up, the current goes down(assuming no change in power) hence the current in the wire will decrease.

In the formula, E=i^2 r t, where i is current, r is resistance and t is time, the energy is directly proportional to i^2. When this is applied to the transportation of electricity in power lines, the energy is wasted. Hence by reduing the current, there is less wastage of energy.

DC 's current or voltage cannot be changed while retaining the same power.

Answer 4

DC current is not used in AC current as it produces heat, when passing through the power lines. The heat loss in DC is so high that it uses up all the electricity to overcome the heat loss. The reason is:
Heat loss in:
a) DC is directly proportional to current flowing through it.
b) AC is directly proportional to the square root of the current flowing through it.

Answer 5

AC is used because DC would lose too much power in traveling the distances from the power plant. AC loses little in transference and (as the other poster stated) easily stepped down.

Answer 6

If you read anything about Tom Edison you well see they had the same question back at the beginning of the 1800 . But to answer you it takes less power to run AC over long distances then DC.

Answer 7

Genie in a Bottle said:

"Heat loss in:
a) DC is directly proportional to current flowing through it.
b) AC is directly proportional to the square root of the current flowing through it."


Absolute rubbish.

Answer 8

AC is used because it can be easily stepped up or down using transformers. Typically they step it up to high voltage for long transmission lengths ...Try here for info

http://www.howstuffworks.com/power.htm