generators
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This document provides an overview of generators, including their principle of operation, history, and types. It discusses how generators work by converting mechanical energy to electrical energy using electromagnetic induction. The history outlines early electrostatic generators and the invention of dynamos and alternators. There are two main types of generators - AC and DC generators - with AC generators being most commonly used in power systems today. Synchronous and induction generators are types of AC generators that are further described.
generators
- 2. Warning Our power point presentation may bore you to death ,but kindly bear with us . PLEASE !!!!
- 3. Context: • Introduction to Generators. • Principle of working. • History of Generators. • Types of Generators.
- 4. Introduction to Generators • The device which converts mechanical energy to electrical energy is called generator MEHANICAL ENERGY GENERATOR ELECTRICAL ENERGY
- 5. Principle of working: • In generators mechanical energy is transformed into electrical energy. • The principle of all of the generators is same, although the detail of construction may be differ somewhat. • A generator has two main parts: • Coil • Magnet
- 6. Principle of working: Generator works on Faraday’s law of electromagnetic induction. When coil is rotated in a magnetic field by some mechanical means magnetic flux is changed through the coil and consequently EMF is induced in the coil.
- 7. History and evolution of Generators • Michel Faraday and Hippolyte Pixii were pioneers who invented early machines like generator. There are following stages of evolution of Generators. • Electrostatic generators. • Principle of electromagnetic induction. • Invention of Dynamos. • Alternators and their evolution.
- 8. Electrostatic Generators: • Before the connection between electricity and magnetism was discovered Electrostatic generators were invented. • They were never used for commercial power generation and were left due to inefficiency and difficulty.
- 9. • An electrostatic generator is an electromechanical generator that produces static electricity, or electricity at high voltage and low continuous current.
- 10. Dynamos: • Dynamos use electromagnetic principles to convert mechanical rotation into a pulsating direct electric current through use of a commutator. • 1st dynamo was built by Hippolyte pixii in 1832.
- 11. Alternators: • Dynamos were succeeded by alternators which was capable of generating ac. • 1st TWO PHASE AC GENERATOR was built by J.E.Gordon in 1882. • Nikola Tesla, Lord Kelvin and Sebastian Ferranti did very useful work in evolution of alternators.
- 12. Types of Generators: • According to output generators are of two types AC generators and DC generators. • According to output generators are of two AC generators and DC generators.
- 13. DC Generator system • They are generally used when the distribution network is small and power required is low (below 2KW). • Can be used only when the load is close to the generator.
- 14. Advantage • It doesn't require a governor and load controller, so the price can be greatly reduced. • Storage batteries may be charged during excess generation to provide for peek loads.
- 15. AC Generator system • Most preferred & conventionally used in all power systems. • Can be singe phase or three phase • Single phase is preferred at low ratings and three phase is preferred at higher ratings.
- 16. Advantage: • Cheaper • More reliable • Maintenance is easy • Profitable
- 17. AC Generators are classified into:- • Synchronous generator • Induction generator
- 18. Synchronous Generator • It has the ability to control the power factor ,so the overall power factor can be improved. • It gives constant speed from no load to full load. • Higher efficiency • Lower running and maintenance cost. • It is a doubly excited machine. The field winding that is rotor is excited using DC source and its stator that is armature winding is excited using AC source.
- 19. Contd… • Starting from its name ‘synchronous’, this gen runs at synchronous speed whatever the amount of load it may be. • it doesn't have self starting torque, so some other auxiliary means have to be provided for starting the synchronous machine. • much costlier that a similar rating induction gen.
- 20. Advantage • Ability to control the power factor. • Speed remains constant irrespective of variation in loads. • It can be constructed with wider air gaps than induction motors which makes these motors mechanically more stable. • usually operate with higher efficiencies ( more than 90%)
- 21. Disadvantage • It cannot be used for a variable speed job. • It requires separate dc excitation. • It cannot be started under loaded condition. • May stop when overloaded • Brushes are required
- 22. Application • Used in power house and sub stations • They’re employed to improve the power factor • Used in controlling the voltage at the end of the transmission line • Used in factories requiring constant speed
- 23. Induction generator • The speed of induction motor is always less than the synchronous speed and it is dependent on the load since the speed decreases with the increase in load. • It is a singly excited machine where its stator windings are excited using an AC source. Contrary to the case of synchronous motor, induction motor works only under lagging power factor.
- 24. Contd… • It is comparatively less efficient. • The cost of induction machine is less when compared with a synchronous motor of same rating. • This kind of motor has its own self starting torque.
- 25. Advantage • Simple & robust construction • Inexpensive • Durability • Has inherent overload protection • More suitable for high speeds • Doesn’t require commutator brush arrangement .
- 26. Disadvantage • Smaller generator cost more per kilowatt to build • High initial cost • Must run parallel with synchronous machine
- 27. Applications Because of distinct superiority of synchronous generator induction generators are rarely used to supply commercial power. They are used in braking purpose of railway.
- 28. Thank you for bearing with us