What is Alternating Current (AC) vs Direct Current (DC)?

The electric current is divided into Direct Current and Alternating Current. Before we talk about what these are, let's remember what the electric current is, how it occurs:

Electrons begin to move by applying a voltage (force) on substances containing free electrons. When electrons move electrically from negative region to positive region, what we call "current" occurs. Direct current (DA or English expression Direct Current, DC) is the constant flow of electrical charges from high potential to low potential. Although the direction of this current does not change, its intensity may change.

ac dc currents

The direct current can be produced with the following sources:

  • Batteries for vehicles that convert chemical energy into electrical energy,
  • From accumulators,
  • From dynamo vehicles that convert alternating current electrical energy into DC electrical energy,
  • Solar panels.

Alternating Current (AA or English expression, AC) is an electrical current whose amplitude and direction change periodically. The most commonly used wave type in this current type is the sine wave. Different waveforms such as triangles and squares are also used in different applications. All waves can be turned to each other via electronic circuits. These cycles are carried out with capacitors, diodes, relays circuit elements.


Alternative current is produced thanks to the devices known as alternators. Alternators are a special type of electric generator designed to produce alternating current. The wire frame is rotated within the magnetic field in the alternators. The time it takes to make a full round turn, i.e. a 360-degree turn, is called T. The wire rotates within the magnetic field, thus entering the voltage current transformation and producing alternating current.

The most commonly used alternative current types are;

  1. One phase AC: This is the most common alternating current energy. It is a frequency of 60 Hz (U.S.) and a voltage of 110-20 volts as used in households.
  2. 120/240 VAC: It shows two phase lines that jointly use a third conductor. There is 120 (120 VAC) between each phase and the common conductor, and 240 volts of alternating voltage (240 VAC) between the surpluses. The difference between excesses is 180°.
  3. 120/280 VAC: The same as 120/240 VAC; however, the angle between the two phases is 120°. Therefore, the compound voltage between the two phases is 280 volts.
  4. 220 VAC or 240 VAC: 120/240 VAC indicates two phases of the system. The single codes 220 and 240 mean that the common conductor is not used at all in general.
  5. 208 VAC: 120/208 Indicates two phases of the VAC system. The only use of code 208 means that the common conductor is not generally used.
  6. Two phases: In fact, this term, which is not exactly true, is used to describe an energy grid that uses two of the phases found in a three-phase system.
  7. Three phases: It is an energy system with three phases. Here, the voltage phases difference between each conductor is evenly divided into 120 degrees.

DC or AC?

In 1893 For Tesla and Westinghouse, the question of whether it was Alternating a direct current or an alternating current was answered by the current wars that had a happy ending. George Westinghouse and Nikola Tesla,founders of Westinghouse, proposed the preference for alternative current for electricity transmission, while Thomas Edison was an advocate of the right current. Edison had to submit to Nikola Teslaafter his defensive efforts were inadequate. Since then, alternating current networks have dominated the transmission of electrical energy all over the world. Such an outcome, of course, must have its reasons. Thanks to transformers, the alternating current can be easily adjusted to any desired value; in addition, alternating current can enable the development of integrated power grids.


Alternating currentalso has significant drawbacks. More than 10%of the electricity is lost every 1,000 kmin the transmission of electricity over long distances by high voltage power lines. In this respect, the direct current seems to be more advantageous. The reason is that direct current transmission systems reduce losses in the power line by 1/3. Alternative current from power plants and wind farmsthanks to electronic power semiconductors with developing technology can be transformed into direct current at affordable prices
and energy loss is minimized.Alternating