Ac Generator New Project 1.doc 2h711w

Submitted To :

Submitted By :

Mr. Anand Mishra

Shubham Rai XII-S1 ROLL.No. 44

Submitted To :

Submitted By :

Mr. S.K. Tiwari

SAURABH PRATAP PARIHAR XII-S2 ROLL.No. ...........

ACKNOWLEDGEMENT I express my deep sense of gratitude of my guide Mr. Mayank

Singh

his

valuable guidance, inspiration and help provided in every aspect of this project. I am thankful to him for his constant evaluation of this project and subsequent in this regard. Last but not the least; I extend my sincere thanks to my Parents, school and Friends, who played an important role in proper tunings of my project.

Neha Verma

Mr. S.K. Tiwari

Class : 10th

Physics Teacher

CERTIFICATE This

is

certify that

Jyoti

Rai of class XII-S2 'Science of Sant

Atulanand

Academy,

Residential

Varanasi

has

prepared this Physics project Half wave Rectifier. In accordance with guide lines followed by C.B.S.E., New Delhi. She has worked as per the instruction and certifies that this process is unique and not copied. Teacher's Signature Mr. S.K. Tiwari

Physics Teacher

CONTENT 1. INTRODUCTION 2. BASIC HALF WAVE RECTIFIER CIRCUIT 3. WORKING

OF

HALF

WAVE

RECTIFIER 4. POWER

SUPPLY

SPECIFICATIONS 5. ADVANTAGES

AND

DISADVANTAGES 6. HALF WAVE RECTIFIER DIODE REQUIREMENTS 7. BIBLIOGRAPHY

INTRODUCTION An electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric current to flow through an external circuit. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air, or any other source of mechanical energy. Generators provide nearly all of the power for electric power grids

THEORY 1. The strong magnetic field is produced by a current flow through the field coil of the rotor. 2. The field coil in the rotor receives excitation through the use of slip rings and brushes. 3. Two brushes are spring-held in with the slip rings to provide the continuous connection between

the

field coil and the external excitation circuit. 4. The armature is contained within the windings of the stator and is connected to the output. 5. Each time the rotor makes one complete revolution, one complete cycle of AC is developed. 6. A generator has many turns of wire wound into the slots of the rotor. 7. The magnitude of AC voltage generated by an AC generator is dependent on the field strength and speed of the rotor. 8. Most generators are operated at a constant speed; therefore, the generated voltage depends on field excitation, or strength.

WORKING All metals contain a movable substance called "electric charge". Even uncharged wires are full of charge! After all, the atoms of the metal are made half of positive protons and half of negative electrons. Metals are special because their electrons don't stay connected to the metal atoms, instead they fly around inside the metal and form a type of electric "liquid" inside the wires. All wires are full of electric fluid. Modern scientists call this the "electron sea" or "electron gas." It is not invisible, it actually gives metals their silvery shine. The electron gas is like a silvery fluid. When a circle of wire surrounds a magnetic field, and the magnetic field then changes, a circular "pressure" called Voltage appears. This circular voltage trys to force the movable charges in the wire to rotate around the circle. In other words, moving magnets create electric currents in closed circles of wire. A moving magnet causes a pumping action. If the circuit is not complete, if there is a break, then the pumping force will cause no charge flow. But if the circuit is "complete" or "closed", then the magnet's pumping action can force the electrons of the coil to

begin flowing. This is a basic law of physics, and it is used by all coil/magnet electric generators. When the circuit is closed and the magnet is moving, charges in the metal are forced to flow. The charges of the light bulb's filament are pushed along. When the charges within the copper wire into the thin light bulb filament, their speed greatly increases. When the charges leave the filament and move back into the

USES 1. Aircraft auxiliary power generation, wind generators, high speed gas turbine generators.

2. Hybrid electric vehicle (HEV) drive systems, automotive starter generators.

3. An ac generator, or 'alternator', is used to produce ac voltages for transmission via the grid system or, locally, as portable generators.

4. All of our household appliances runs on ac current. Ex: Refrigerator, washing machines, oven, lights, fan etc.

EFFICIENCY Expression for Instantaneous e.m.f. Produced: Let position of the coil at any time t. It make angle q with vertical. If w is uniform angular speed of the coil. Then q = wt B be the strength of magnetic field n be the number of turns in the coil and A area of the coil then magnetic flux with the coil in this position is given by: f = nBA Cos q = nBA Cos wt. Differentiate w.r.t. time = nBA (-Sin wt) w = -nBA w Sin wt e = - (-nBA w Sin wt) maximum value of e.m.f. say E0 e = E0 Sin wt.

1) Efficiency of an AC generator is the ratio of the useful power output to the total power input. 2) Because any mechanical process experiences some losses, no AC generators can be 100 percent efficient.

3) Efficiency of an AC generator can be calculated using Equation. 4) Efficiency =(Output /Input ) × 100

I want to give my special thanks to subject teacher Mr. S.N. Mishra for

giving

him

precious

time

in

completion of my project work and also to the Lab assistance Mr. Kashi for guiding me in my practical works. They helped me from the moment I started my project to the end of it.