DC Generator

Electrical generators are self-contained units that generate power when the local grid is unavailable. During power outages, these generators provide backup power to businesses and homes. Generators do not produce electrical energy; instead, they convert mechanical or chemical energy into it. Generators are divided into two types based on their output: AC generators and DC generators. In this article, we’ll go over DC generators in depth.

Generators

Generators are divided into two categories: DC generators and AC generators. Mechanical energy is converted to electrical energy by both DC and AC generators. A DC generator generates direct current, whereas an AC generator generates alternating current.

Both of these generators work on the idea of Faraday’s law of electromagnetic induction to generate electricity. According to this law, as a conductor travels in a magnetic field, it breaks magnetic lines of force, causing an electromagnetic force (EMF) to be induced in the conductor. The rate of change of flux (magnetic line force) linkage with the conductor determines the magnitude of this produced EMF. If the conductor circuit is closed, this EMF will induce current to flow.

Parts of a DC generator:

• Stator- A stator is a pair of magnets arranged in such a way that their opposite polarities face each other. The stator’s job is to generate a magnetic field in the area where the coil spins.

• Rotor- A rotor is a slotted, cylindrical laminated armature core.

• Armature Core – The armature core features grooves on the exterior surface and is cylindrical in shape. The armature winding is accommodated in these spaces.

• Armature winding- The insulated conductors in the armature core are known as the armature winding. The actual power transfer occurs as a result of these.

• Yoke – Yoke is the exterior hollow cylindrical structure. It supports the main and inter poles while also providing a low resistance channel for the magnetic flux.

• Commutator – The commutator is shaped like a cylinder. A commutator is made up of several wedge-shaped, hard-drawn copper segments. A commutator’s functions are as follows:

1. Brushes and wires are used to connect stationary external circuits to revolving armature conductors.

2. Induced alternating current is converted to direct current.

How does a simple generator work?

When a conductor is placed in a fluctuating magnetic field (OR when a conductor is moved in a magnetic field), an emf (electromotive force) is generated in the conductor, according to Faraday’s rules of electromagnetic induction. The magnitude of the induced emf can be estimated using the dc generator’s emf equation. The induced current will circulate within the closed path if the conductor is equipped with one. Field coils create an electromagnetic field in a DC generator, and the armature conductors rotate into it. In the armature conductors, an electromagnetically induced emf is therefore formed. Fleming’s right-hand rule determines the direction of induced current. 

When the direction of motion of the conductor changes, the direction of induced current changes, according to Fleming’s right-hand rule. Consider a clockwise rotating armature with a conductor travelling upward to the left. The direction of motion of that particular conductor will be reversed to downward after the armature completes a half rotation. As a result, the current in each armature conductor will alternate in direction. If you look at the diagram above, you can see how the induced current in an armature conductor alternates in direction. When the current is reversed in a split ring commutator, however, the connections of the armature conductors are likewise reversed. As a result, the terminals receive unidirectional current.

DC generator output formula

The formula for the output of a DC generator is given as:

E=PZN60A

Here,

P is the total number of poles

is the magnetic flux per pole

Z is the total number of armature conductor

N is the angular speed of the armature in rotations per minute

A is the number of parallel paths

Types of DC generators:

Separately excited DC generators and self-excited DC generators are the two primary classifications.

1. Separately excited: Field coils are powered from a separate external DC source in this configuration.

2. Self-excited: In this case, the field coils are powered by the generator’s own current. Residual magnetism in field poles causes the initial emf emission. The created emf forces a portion of the current to flow in the field coils, hence boosting field flux and emf generation. The three types of self-excited dc generators are as follows:

1. Series wound – field winding in parallel with armature winding 

2. Shunt wound – field winding in series with armature winding 

3. Compound wound – series and shunt winding combined

Applications of DC generator

• Using field regulators, an independently excited type DC generator is employed for power and lighting.

• Arc lamps use a series DC generator for a reliable current generator, illuminating, and booster.

• Compound at a reasonable level Hostels, offices, and lodges rely on DC generators for power.

• Power for DC welding machines is provided by compound DC generators.

• To compensate for the voltage loss in the feeders, a DC generator is required.

Conclusion

A DC generator can theoretically be utilised as a DC motor without any modifications, and the reverse is also conceivable. A DC machine can thus be defined as a DC generator or a DC motor. These fundamental building characteristics also apply to the development of a DC motor.