Construction of a DC Generator
Below is a schematic representation of a DC generator :
Construction of a DC generator
Components of DC Generator
Components of DC Generator are given below :
- Yoke
- Magnetic Field System
- Armature Core
- Armature Winding
- Commutator
- DC Generator Commutator Function
- Shaft
- Pole Shoe
- Poles
- Bearings
Yoke
The outside frame of a DC generator is a hollow cylinder made of cast or rolled steel, known as a yoke. The yoke provides the following two objectives.
- It supports the field pole core and serves as a protective cover for the machine.
- It offers a channel for the magnetic flux produced by the field coil.
Magnetic Field System
A DC generator’s magnetic field system serves as its stationary component. It generates the primary magnetic flux in the generator. It is made up of a large number of pole cores fastened to the yoke with field winding coiled around the pole core. The field arrangement of a DC generator features prominent poles, such as poles that thrust inwards, and each pole core has a post shoe with a curved surface. The shaft shoe has two objectives.
- It provides support for the field coils.
- It lowers the reluctance of a magnetic circuit by expanding its cross-sectional area.
To prevent eddy current loss, the pole cores are constructed of thin, insulated sheet steel laminations. The field coils are linked in series to create alternating north and south poles in the rotating direction as the current flows through them.
Armature Core
The armature core of a DC generator is positioned on a shaft and pivots between the field poles. It features slots on its exterior surface where the armature conductors are installed. The armature core is made up of soft iron laminations that are isolated from one another and securely Attached together. In big machines, the laminations are keyed, but in tiny machines, they are keyed directly to the shaft. The laminated armature core helps to decrease eddy current losses.
Armature Winding
The insulated conductors are inserted into the slots of the armature core. The wires are properly connected. The linked arrangement of conductors is known as armature winding. There are two types of armature windings used: wave winding and lap winding.
Commutator
A commutator is a mechanical rectifier that converts the alternating magnetic field of the armature winding into a direct voltage that runs through the load terminals. The commutator is constructed up of wedge-shaped copper segments that are isolated from one another and the shaft by mica sheets. Each commutator segment is connected to one of the armature coil’s ends.
DC Generator Commutator Function
The basic purpose of the commutator is to convert DC to AC. It functions as a reversing switch, and its purpose in the generator is explained below.
The electromagnetic field produced within the generator’s armature coil alternates, leading to an alternating current flowing within the armature coil.This current may be reversed through the commutator at the precise moment that the armature coil crosses the magnetic unbiased axis. As a result, the load develops a DC or unidirectional current.
The commutator ensures that the current flowing from the generator continues in the same direction indefinitely. By moving along the commutator, the brushes create high-quality electrical connections between the generator and the load.
Shaft
The shaft is a key component of a DC machine because it produces torque, which causes rotation. It is constructed of mild steel and has the highest breaking strength. The shaft is a component of a DC generator that influences the generator’s ability to transport mechanical energy. The shaft is keyed to the commutator, cooling fan, armature center, and other spinning components.
Pole Shoe
A pole shoe is a plate composed of iron or steel that spreads magnetic flux and prevents field coils from falling.
Poles
Poles help maintain the field windings in excellent shape. These windings are generally coiled on poles and linked in a certain order to the armature windings. As a result, the posts attach the welding procedure to the yoke using screws.
Bearings
Bearings are used in a system to ensure that the various parts of a DC machine move smoothly. The friction between the machine’s spinning and stationary elements is reduced with the aid of course. As a result, the system’s components require less frequent greasing and will last longer. Roller bearings and ball bearings are the two most popular types of bearings used in dc generators.
Construction And Working of a DC Generator
In 1831, Michael Faraday, a British physicist, devised the electromagnetic generator. The primary function of this device is to convert mechanical energy to electrical energy. There are several types of mechanical energy sources available, including hand cranks, internal combustion engines, water turbines, and gas and steam turbines. The generator provides capacity for all electrical power networks. An electric motor should be able to perform the generator’s converse function. The basic purpose of the motor is to convert electrical energy into mechanical energy. Generators and motors have many properties.
Table of Content
- DC Generator
- Construction of a DC generator
- Workings
- Types
- Losses in DC Machines
- Characteristics of DC Generator
- Characteristics of DC Series Generator
- Characteristics of DC Shunt Generators
- External Load Characteristics of the DC Compound Generator
- Efficiency of a DC Generator