The whole idea of getting a giant generator on any large scale event stressed the importance of a device which can handle the burden of converting a large amount of mechanical energy to electrical energy. It was fulfilled when the dynamo was replaced by this compact system of iron cores and electromagnetic fields called the ‘generator’. It produced either AC power or DC power with respect to its principle of function i.e. ‘The Faraday’s Law of Electromagnetic Induction’. It states that when a current carrying conductor moves inside a magnetic field, it cuts through the magnetic lines and results in a change of flux through the system. This current produced an Electromotive force (EMF) which causes the current to move in the opposite direction of the conductor. To talk about a simple DC Generators, a single/multiple rectangular or square loop of conductor is placed in between the opposite poles of a magnet.
When current courses through the rectangular apparatus, the sides which are parallel to each other and in the same direction of the magnetic field have no effect on magnetic field. The lines which cut the magnetic lines of forces and change the magnetic flux are the ones which are responsible for the generation of Magnetic flux. In automobiles, the 4-pole DC Generator gives us insight into its working. The outer frame of the motor is called as a yoke. It is made up by steel or cast iron. It provides mechanical strength for the whole structure and also carries the magnetic flux when the generator starts working. The poles are welded to the yoke and hold the core of the apparatus. The number of armature windings decides the strength of the generator and the amount of electricity it can produce.
The commutator and brushes help in the movement of the generated electromotive force. They are connected to the armature core to establish proper movement of the EMF with the rotating rotor. Moreover, an alternator or a DC Generators uses solid rings which wear out less often than brushes. This eventually reduces the making and breaking of the circuit and thus parts can be utilised for a longer period of time. But if you look at the bigger picture, our generation is all about commercial power generation and AC is the unequivocal winner. Today, all the transformers can be used with the help of AC current. Thus, the process of step up and step down comes in handy.
When DC current is used for long distance transmit, it may provide a larger ratio of power loss than AC, but it eventually is the most direct way of current.