By the word Generator we can understand that, it’s generate something. In Electrical Engineering Generator mainly use for Electricity Generation. But Generator cannot generate electricity by itself. It need a prime mover that helps generator to rotate and by this rotation inside the generator creates magnetic flux and create electricity.
Around the world there is a need of generators for many different applications. Everything is the underlying need for a public supply of smooth electricity. We will find number of situations in which independent electricity supplies are needed. In this post we will know the different applications of Generator and its types.
The applications for Generators are categorized follows:
- In grid system for public supply networks a number of high power generator sets may operate in parallel from different power station.
- Sometime private or independent generators may run in parallel with the public supply system or isolated from it when demand is less. No problem I am going to give you some example of it.
- Peak shaving to reduce the maximum demand of electricity consumed by a user and this can avoid large financial penalties during times of normally high demand on the grid system.
- Keep standby or emergency generators to protect the supply to the critical circuits such as a hospitals, fire service and water supply system.
- Sometime is required some temporary supply system by the construction industry or in cases of any breakdown.
- Some portable supplies, often trailer-mounted, where alternative supply system is not available.
There are two main types of generator like ‘Turbo’ or cylindrical-rotor and another one is salient-pole generators. Both of these types are synchronous machines. In which the rotor turns in exact synchronism with the rotating magnetic field in the stator section.
But most generators found under this class and it forms the basis of most of the chapter. The largest generators used in most major power stations are usually turbo type generators. This type of generator operates at high speeds and it’s usually directly coupled to a steam or a gas turbine.
This generator rotor is made from the solid steel for strength and embedded in slots with the rotor are the field or the excitation windings. The outer stator of the generator also contains windings which are located in slots and this is again for mechanical strength, so that the teeth between the slots form a good magnetic path.
The most of constructional features is very specialized such as hydrogen cooling system instead of air cooling system and the direct water cooling inside the stator windings so that only passing reference is made to this class of machines in the following descriptions.
This type of generator commonly used in smaller and medium power ranges is the salient-pole generator. Here the rotor windings are wound around the poles which project from the centre of the rotor. But the stator construction is similar in form to the turbo-generator stator and it less commonly used are induction generators and the inductor alternators.
Induction generators use to have a simple form of rotor construction in which aluminum bars are cast into a stack of laminations. Aluminum bars require no insulation and the rotor is therefore much cheaper to manufacture and it’s much more reliable than the turbo and the salient-pole generator.
Inductor alternators have laminated rotors with slots and producing a flux pulsation in the stator as the rotor turns. These type of machines are usually used for specialized applications where requiring high frequency.
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