Generators are useful appliances that supply electrical power during a power outage and prevent discontinuity of daily activities or disruption of business operations. Generators are available in different electrical and physical configurations for use in different applications. In the following sections, we will look at how a generator functions, the main components of a generator, and how a generator operates as a secondary source of electrical power in residential and industrial applications.
How does a generator work?
An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output.
It is important to understand that a generator does not actually ‘create’ electrical energy. Instead, it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. This mechanism can be understood by considering the generator to be analogous to a water pump, which causes the flow of water but does not actually ‘create’ the water flowing through it.
The modern-day generator works on the principle of electromagnetic induction discovered by Michael Faraday in 1831-32. Faraday discovered that the above flow of electric charges could be induced by moving an electrical conductor, such as a wire that contains electric charges, in a magnetic field. This movement creates a voltage difference between the two ends of the wire or electrical conductor, which in turn causes the electric charges to flow, thus generating electric current.
Main components of a generator
The main components of an electric generator can be broadly classified as follows;
- Engine
- Alternator
- Fuel System
- Voltage Regulator
- Cooling and Exhaust Systems
- Lubrication System
- Battery Charger
- Control Panel
- Main Assembly/Frame
AC and DC Generator: The electrical machine is a device that converts mechanical energy into electrical energy & vice versa. The Generator is a type of machine that converts mechanical energy into electrical energy. However, the electrical energy generated can be either in AC or DC form. Therefore, the main point of difference between AC and DC generator is that it generates AC and DC electrical energy respectively. There are few similarities but there are quite a lot of differences between these two generators.
AC Generator is a generator that converts mechanical energy into AC electrical energy. It is a type of generator designed to generate alternating current with a frequency of 50 or 60 Hz.
Key Differences between AC & DC Generator
| AC Generator | DC Generator |
| It is a mechanical device that converts mechanical energy into AC electrical energy. | It is a mechanical device that converts mechanical energy into DC electrical energy. |
| It is also called alternator or AC generator depending on their construction. | It is also called Dynamo. |
| The current is induced in either the rotor (of AC generator) or the stator (of Alternator) depending on its construction. | The current is induced in the rotor. |
| It generates an alternating current that reverses direction periodically. | It generates a direct current that remains in only one direction. |
| There are no commutators in AC generator. | It has commutators to supply unidirectional current. |
| It uses a slip ring to transfer the induced current smoothly to the circuit. | It uses split rings to transfer the induced current to the circuit & also convert the induce AC into pulsating DC. |
| The generated output voltage amplitude is relatively higher. | The output voltage amplitude is relatively lower. |
| There are low energy losses in the slip rings of AC generator. | There are higher energy losses in the split rings of the DC generators due to sparks. |
| There is no limitation of the voltage generated by the AC generator. | The commutator can be damaged by increasing the voltage due to sparks between them. So DC generators have a voltage limit. |
| The smooth operation of the slip ring increases the brushes life-time. | The split ring wears out the brushes due to sparks between them. it requires periodic replacement. |
| There is no issue of short circuit between the rings. | The brushes sliding across the split ring may cause a short circuit between them. |
| It does not need frequent maintenance & is more reliable. | They are not very reliable & require frequent maintenance. |
| It has relatively higher efficiency due to smooth operation of slip ring than DC generator. | It has relatively lower efficiency due to the inefficient operation of the split ring. |
| It has a simple design. | It has a complex design. |
| The overall cost is low in the long run. Although the initial cost is higher than the DC generator. | The overall cost is expensive due to costly maintenance, but the initial cost is lower than the AC generator. |
| The frequency of the generated output depends on the rotational speed of the armature. | There is no frequency so the rotational speed does not affect it. |
| The generated AC output can be easily converted into low & high voltages for long-distance transmission. | The generated DC output is not efficient for transmission because it needs a costly converter with multiple losses. |
| They are used for supplying power to appliances in office & homes such as lights, fans, mixers, washing machines etc. | They are generally used for powering large DC motors such as in subways systems & charging backup batteries. |
0 Comments