INTERNAL POWER FACTOR ANGLE OF SALIENT POLE THREE PHASE ALTERNATOR WORKING UNDER LEADING POWER FACTOR LOAD THIS PPT CONTAINS SO MUCH USEFUL INFORMATION ABOUT THE ALTERNATOR WORKING IN THER LEADING POWER FACTOR AND THE CONDITIONS ARE ALSO MENTIONED IN THE PPT AND THE PHASOR DIAGRAMS ARE ALSO DRAWN IN THE PPT AND IT IS SO USEFUL FOR THE STUDENTS FOR ABOUT ELECTRICAL MACHINES

1. Raghu Engineering College
Department of Electrical & Electronics Engineering(Autonomous)
Accredited by NBA & NAAC with ‘A Grade, Permanently Affiliated JNTU Kakinada
Dakamarri (v), Bheemunipatnam Mandal, Visakhapatnam, Andhra Pradesh 531162
A CASE STUDY ON
INTERNAL POWER FACTOR ANGLE OF SALIENT POLE THREE PHASE
ALTERNATOR WORKING UNDER LEADING POWER FACTOR LOAD
UNDER THE GUIDANCE
Mr.M.SRIKANTH
ASSOCIATE PROFESSOR
BY
P. ESWAR SAI 18981A0241
P.MOHAN 18981A0241
P.SUPRIYA 18981A0241
P.NITHESH KUMAR 18981A0241
P.SANJAY KUMAR 18981A0241
BACHELOR OF TECHNOLOGY
IN
ELECTRICAL AND ELECTRONICS ENGINEERING

2. CONTENTS :-
• INTRODUCTION (SYNCHRONOUS MACHINES )
• CONSTRUCTION
• VARIOUS TYPES OF ROTORS
• SALIENT-POLE SYNCHRONOUS GENERATOR
• OPERATION PRINCIPLE
• ELECTRICAL FREQUENCY
• GENERATED VOLTAGE
• EQUIVALENT CIRCUIT
• PHASOR DIAGRAM

3. SYNCHRONOUS MACHINES :-
• Synchronous generators or alternators are used to convert mechanical power
derived from steam, gas, or hydraulic-turbine to ac electric power
• Synchronous generators are the primary source of electrical energy we consume
today
• Large ac power networks rely almost exclusively on synchronous generators
• Synchronous motors are built in large units compare to induction motors
(Induction motors are cheaper for smaller ratings) and used for constant speed
industrial drives

4. CONSTRUCTION :-
➢ Basic parts of a synchronous generator:
• Rotor - dc excited winding
• Stator - 3-phase winding in which the ac
emf is generated
➢ The manner in which the active parts of a synchronous
machine are cooled determines its overall physical size and
structure

5. VARIOUS TYPES :-
• Salient-pole synchronous machine
• Cylindrical or round-rotor synchronous
machine

6. SALIENT-POLE SYNCHRONOUS GENERATOR :-
1. Most hydraulic turbines have to turn at low speeds (between 50 and 300 r/min)
2. 2. A large number of poles are required on the rotor

7. SALIENT-POLE SYNCHRONOUS GENERATOR :-

8. OPERATION PRINCIPLE :-
The principle of operation of synchronous generator is
electromagnetic induction. If there exits a relative motion
between the flux and conductors, then an emf is induced in the
conductors. ... Thus, now we can say that the conductor
tangential motion is perpendicular to magnetic flux lines from
north to south pole.

9. ELECTRICAL FREQUENCY :-
• Electrical frequency produced is locked or synchronized to the mechanical
speed of rotation of a synchronous generator:
where fe = electrical frequency in Hz
P = number of poles
nm= mechanical speed of the rotor, in r/min

10. GENERATED VOLTAGE
The generated voltage of a synchronous generator is given by
where
∅= flux in the machine (function of If )
fe = electrical frequency
Kc= synchronous machine constant

11. EQUIVALENT CIRCUIT--1
 The internal voltage Ef produced in a machine is not usually the voltage
that appears at the terminals of the generator.
 The only time Ef is same as the output voltage of a phase is when there is
no armature current flowing in the machine.
 There are a number of factors that cause the difference between Ef and Vt.
• The distortion of the air-gap magnetic field by the current flowing in the
stator, called the armature reaction
• The self-inductance of the armature coils.
• The resistance of the armature coils. The effect of salient-pole rotor
shapes.

12. EQUIVALENT CIRCUIT :-

13. PHASOR DIAGRAM OF A :-

14. PHASOR DIAGRAM OF A :-
Common terms used in the work
θ = Angle between line voltage and stator
current
φ = Angle between field voltage and stator
current
δr = Angle between field voltage and resultant
voltage (rotor angle)
α = Angle between resultant voltage and line
voltage
δ= Angle between field voltage and line
voltage (torque angle)

15. REFERENCES :-
[1] Onuegbu J. C., Design and performance analysis of a three phase
Synchronous Motor, A dissertation at the Department of Electrical
Engineering. Nnamdi Azikiwe, University, April 2012.
[2] Cathey Jimmie A., Electrical Machines, Analysis and design Applying
matlab.
[3] Say M. G. Alternating Current Machine, Pitman publishing House
London, 1976. [4] Tokarev B. F. Electrical Machines..