Difference between AC and DC Electric transformers

As most of us are aware, electricity flows in two ways - either as alternating current (AC) or as direct current (DC). Electric current can be described as the moving electrons along a conductor, like a wire, that have been harnessed for energy. Therefore, simply stated, the difference between AC and DC is the direction in which the electrons flow. In DC, the electrons flow steadily in a single direction that is forward. In AC, electrons keep switching directions, sometimes going forwards and then going backwards. The power that comes from our wall outlets, at the various buildings including our homes, is the more common AC.

Now, alternating voltage is carried around the country in cables far more efficiently than direct current where the voltage is fixed. So the electricity that arrives at our house is still alternating voltage. Electric light bulbs and fires can run on 230 volt AC. Other equipment such as televisions has an internal power supply which converts the 230 volts AC to a low DC voltage that is safe and acceptable to the electronic circuits.

In the search to create electrical energy, scientists discovered that electrical and magnetic fields are related. A magnetic field near a wire causes electrons to flow in a single direction along the wire because they are repelled and attracted by the north or south poles. Thus, DC power from a battery was born. Another scientist, Nikola Tesla, preferred AC because it travels farther without losing energy and could transfer different amounts of power. Instead of applying the magnetism along the wire steadily, he used a magnet that was rotating. When the magnet was oriented in one direction, the electrons flowed towards the positive, but when the magnet's orientation was flipped, the electrons turned as well. AC generators gradually replaced DC battery system as AC was found safer to transfer over the longer distances and provided more power.

The AC's voltage from a generator, in a power plant, can be pushed up or down in strength by another device called a transformer. Transformers are ubiquitously found on the electrical pole at street corners. They change very high voltage into a lower voltage appropriate for your home appliances, like lamps and refrigerators. AC can even be reverted to DC by an adaptor that you might use to power the battery on your laptop.

As we know, electrical transformers are used to transform voltage from one level to another, usually from a higher voltage to a lower voltage. This is done by applying the principle of magnetic induction between coils to convert voltage and/or current levels. A transformer combines several major characteristics of electricity and magnetism to change AC voltages. DC transformers are now available, but they won't replace AC transformers.

You can see that DC voltages could not be changed with the configuration of the transformer. This is because the DC current would not be changing the magnetic field in the manner AC current does. And this was the reason that AC scored over DC when electricity started to be used around the world. Since then, electrical engineers have developed DC transformers, primarily using special circuitry. Since everyone now uses AC, it is too late to change to DC system.