Electric current

History of alternating current, discovery and distribution

History of alternating current, discovery and distribution

Alternating current is one of two types of electrical current with which electricity can be transmitted.

Alternating current generators produce electricity in alternating current. AC generators convert mechanical energy into electrical energy. 

In the industrial origins of electricity use, the electrical system used in the nineteenth century was direct current. However, with the arrival of alternating current by the scientist Nikola Tesla the world was revolutionized again.

Who discovered the electromotive force?

It was discovered by the British Michael Faraday in 1831. Faraday noticed that a conductor rotating in parallel within a magnetic field generates a constant electronic flux. As a result, we can do mechanical work with this flux.

This discovery was electromagnetic induction, and it was shown that electric fields and magnetic fields acted in the same way (the electromagnetic force). A few decades later, James Clerk Maxwell expressed this discovery with fundamental equations.

Who devised the current alternating current distribution system?

Nikola Tesla was the first person who proposed to carry out electricity distribution with the alternating current. At that moment, he was working for Thomas Alva Edison's company.

In 1887, Nikola Tesla managed to build the first prototype of an induction motor. It worked thanks to a particular type of electric current, in which the electrons change their direction according to recurring alternations.

Tesla realized that AC generators emitted an electrical flux that changed polarity several times over a certain period.

Inconvenient of direct current (DC) power transmission

The main problem was being able to find an efficient way to transport electricity from power plants.

At that time, electric current was distributed in the way it was generated in dynamos: direct current. As a result, the flow of electrons never changed direction, and the positive and negative poles remained unchanged over time.

Direct current distribution presents the problem that over long distances heats the electric cable and causes dissipation. Thus, increasing the amperage increasing costs and energy waste is necessary to compensate for this problem.

On the other hand, alternating current systems allow the voltage to be raised and distributed over great distances without significant energy losses. 

Distribution by alternating current (AC)

This new type of current can drastically reduce energy losses over long distances by increasing voltage making it more efficient. 

Increased voltage is dangerous for living things. Therefore, it is necessary to reduce the voltage before its distribution in homes or factories through a transformer. The first transformer for this purpose was developed by Lucien Gaulard and John Dixon Gibbs.

The transformer makes it possible to bring the potential difference (voltage) to very high levels (high voltage) and decrease the amperage to shallow values.

The physicist William Stanley tried to solve the same problem, in 1885. He reused the principle of induction to transfer alternating current between two electrically isolated circuits. However, it hadn’t many success. Thus, the system used today was devised by Nikola Tesla.

Why is the electrical distribution carried out in alternating current?

The main reasons are:

  • Lower long-distance energy losses.

  • AC motors are more reliable and efficient.

Tesla proposed to his boss Edison, founder of General Electric, to adopt an alternating current distribution system to solve the long-distance transmission problem. However, Edison refused for economic reasons. The distribution system he invented was the only one used in factories, and General Electric had a commercial monopoly. 

However, the advantages of the Tesla system allowed prevailed over Thomas Edison's DC. This fight in the well-known “war of the currents.”  In the battle of currents, the point was to decide which system of currents was better to implement in the United States.

Westinghouse’s company bought Tesla’s AC power system patents. Then, he won some bids to supply electrical power, such as the most significant part of the contract to build Niagara Falls hydroelectric power station. DC commercial power distribution systems declined rapidly in the 20th century. The last DC electric lighting in New York City was shut down in 2007.

Alternating current (AC) system spread thanks to the use of the transformer. In this way, the power is maintained unchanged when transmitting it over long distances.

Publication Date: July 16, 2021
Last Revision: July 16, 2021