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Advantages and disadvantages of A.C. over D.C.

In this article learn about the advantages and disadvantages of AC current over DC current. Both types of electric current have their advantages and disadvantages. In 1882, New York City developed the first electric power system.

AC is the short form used for Alternating Current and DC is the short form used for Direct Current. In a circuit direct current flows only in one direction and alternating current flows in both the direction. 

A.C. and D.C.
Figure showing both alternating and direct current

Learn more about Alternating current and EMF


  • The generation of A.C. is cheaper than that of D.C.
  • A.C. machines are simple, robust and do not require much attention for their repairs and maintenance during their use. For example, the transformer necessary to provide alternating current power is quite affordable and involves less maintenance cost.
  • A wide range of voltages is obtained by the use of a transformer.
  • The magnitude of the current can be reduced by using an inductance or a conductor without any appreciable loss of energy
  • A.C. can easily be converted into D.C. with the help of rectifiers.
  • When A.C. is supplied at higher voltages in long-distance transmission, the line losses are small compared to a D.C. transmission.
  • Efficient electric power transformation over long-distance lines can be achieved through the use of a transformer. 


  • The peak value of A.C. is high and it is dangerous to use so better insulation is required.
  • It attracts a person who touches it, unlike D.C. which gives a repelling shock.
  • An A.C. is transmitted from the surface of the conductor and hence need several strands of thin wires insulated from each other.

In the beginning, there was a debate over whether the electrical utility business should be standardised with ac power or dc power.
Due to a number of advantages, alternating current power has surpassed direct current power. The transformation of voltage levels in ac power allows electrical power to be created at low voltage and then step up for transmission over long distances to reduce $I^2R$ losses, and then step down at the distribution end to reduce $I^2R$ losses. This step-up and step-down of voltage is achieved with the help of a transformer.

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