DC Generator – Working Principle, Elements and Types

Electrical generators are standalone machines that give power when control from the nearby network is inaccessible. These generators supply reinforcement control to businesses and homes amid control blackouts. Generators don’t make electrical vitality, but they change over mechanical or chemical energy into electrical energy. Based on the yield, there are different generator components such as AC and DC sorts of generators.

In this article, we’ll be examining a DC generator in detail.

Meaning and definition of DC type of generators

DC sorts of generators are electrical machinery whose actual work is to change mechanical vitality into power. This electromotive drive can cause a stream of current when the conductor circuit is closed. When the conductor cuts attractive flux, it will produce an EMF-based on Faraday’s electromagnetic acceptance guideline of Faraday’s Laws.

Elements of the generator 

This generator can be bestowed as a DC engine without changing its development. Below, we have said the essential segments of this generator.

  • Stator: The real work of this is to supply attractive areas in which the coil turns. A stator engulfs two magnets with reversed extremities confronting one another. It is located to fit within the locale of the rotor. 
  • Rotor: incorporates open press layers with spaces that are stacked to shape around and hollow armature centre. The work of the cover is to diminish the misfortune caused due to whirlpool current.
  • Poles: The work of a shaft is to hold the field windings. These windings are wound on posts and are either associated in arrangement or parallel by the armature windings.
  • Armature Windings: Armature windings are made in a closed-circuit shape associated in arrangement to do parallelling for upgrading the entirety of created current.
  • Yoke: The outer structure of the generator is known as Burden. It is made of either cast press or steel. It gives essential mechanical control for carrying the magnetic flux given through the poles.
  • Post Shoe: The purpose of a pole shoe is to spread the attractive flux to avoid the field coils from falling. 
  • Commutator: works as a rectifier that changes AC to DC inside the armature winding. It is found on the shaft of the machine. It is planned with a copper section, and each copper section is secured from the other with the assistance of mica sheets.
  • Brushes: The electrical associations are guaranteed between the commutator and the external load circuit with the assistance of brushes.

The principle behind working of the generator

According to Faraday’s law of electromagnetic acceptance, we know that when a current-carrying conductor is put in an attractive shifting field, an EMF is commenced within the conductor. Concurring to Fleming’s right-hand runs the show, the heading of the actuated current changes at whatever point the course of movement of the conductor changes. 

Let us consider an armature pivoting clockwise and a conductor at the cleared out moving upwards. When the armature completes a half revolution, the course of the conductor’s movement will be switched descending. Consequently, the heading of the current in each armature will be substituting. When a current passes, associations of the armature conductors get switched along with a part ring commutator; thus, we acquire a unidirectional current at the ends.

EMF Equation for the Generator

If the following values are considered:

P – the number of poles of the machine

ϕ – in Weber, let it be the flux per pole.

Z – The Total number of armature conductors.

N be the Speed of armature in revolution per minute (RPM).

A is the number of parallel paths in the armature winding.

Hence, the equation is 

Kinds of losses in a DC kind of generator

Four inside losses make contributions to decreasing the efficiency of this generator.

  • Copper Losses: Copper loss is the vitality misplaced as warmness within the windings; it is agitated by utilising the drift of modern through the coils of the  DC field. This loss changes directly with the square of contemporary in armature or area and the resistance of the field coils.
  • Eddy Current Losses: As the armature pivots inside the field, it cuts the follows of flux at an identical time. The copper coils of wires wound on the armature cut the strains of instability. Since the armature formed of iron, an EMF induced, motivating a current flow. These types of circulating currents within the iron core are eddy currents. A laminated (layered) steel sheet is used for the armature and discipline cores to limit eddy currents. The stratified sheets are insulated so that current cannot drift from one sheet to the other.
  • Hysteresis Losses: It occurs when the armature rotates in a magnetic field. The magnetic domains of the field are held in alignment with the discipline in varying numbers, established upon area strength. The magnetic parts rotate with direction to the particles which are not aligned—being done with the aid of one whole turn during every rotation of the armature. This rotation of magnetic domains present in the iron motivates the friction along with the heat.
  • Mechanical Losses: Mechanical losses, also called Rotational losses, can be accelerated by implying the bearing contact, brush grinding on the commutator, or discuss grinding (called windage). Then they are actuated by way of the discussed turbulence due to the armature revolution. Careful protection can be instrumental in protecting the bearing friction to its minimum level.

Operations of these generators

  • The independently energised generator gets used for control and lighting purposes using the field regulators. 
  • The arrangement generators get used in circular segment lights for a steady current generator, lighting, and booster. 
  • Level compound generators are utilised to supply control to lodgings, workplaces, lodges. 
  • Compound generators get handled for providing control to DC welding machines.
  • This type of generator is employed to compensate for the voltage drop within the feeders.

Types of such generators

Generally, this kind of generator is categorised into three categories stated as a permanent magnet, separately excited, and self-excited and further subdivided into series, shunt, and compound generator.

  • Permanent magnet: This kind of generator that utilises lasting magnets to make the flux within the attractive circuit is the permanent magnet DC-type generator and the foremost fundamental generator.  This sort cannot supply much control due to the plan of the generator and does not utilise in industry applications. Permanent magnet DC-type generators ordinarily are being used in little applications, the same as dynamos in cruisers.
  • Separately Energised: External DC source (e.g., battery) is utilised in this framework to energise field magnets. The better the revolution speed, the better the EMF and voltage.
  • Self-Excited: have field magnets that get energised by their possess to provide current. The field coils are associated with the armature inside. Shunt Wound Generators, Compound Wound Generators, Series Wound Generators are some types of self-excited generators. 


Understanding the differences between a DC and AC generator involves understanding the different workings of the two. Now that you have gone through the different types, elements and such of the DC-type generators, you can read more about AC generators.