Electrical Machines 3 Pdf Notes – EM III Notes | Free Lecture Notes download


Here you can download the free lecture Notes of Electrical Machines 3 Pdf Notes – EM III Notes Pdf materials with multiple file links to download. The Electrical Machines 3 Notes pdf – EM III Notes Pdf  book starts with the topics covering Constructional Features of round rotor and salient pole machines,  suppression of harmonics, Regulation by synchronous impedance method, Parallel Operation of Synchronous Generator Synchronizing alternators with infinite bus bars, Theory of operation, Excitation and power circles, Single phase induction motor, Principle & performance of A.C. Series motor-Universal motor, Etc.

Electrical Machine III Notes - EM III Notes - EM Pdf Notes, Electrical Machine 3 Pdf Notes - EM III Notes Pdf
Electrical Machines III Notes (EM-III) –

Electrical Machines 3 Pdf Notes – EM III Notes Pdf

Objective : Electrical Machines 3 Notes – EM III Notes 

This subject is an extension of previous machines courses. It deals with the detailed analysis of Synchronous generators and motors which are the prime source of electrical power generation and its utilities. Also concerns about the different types of single phase motors which are having significant applications in house hold appliances and control systems.

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Unit 5

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Complete Notes :-

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Construction and Principle of operation

Constructional Features of round rotor and salient pole machines – Armature windings – Integral slot and fractional slot windings; Distributed and concentrated windings – distribution, pitch and winding factors – E.M.F Equation.


Synchronous Generator Characteristics

Harmonics in generated e.m.f. – suppression of harmonics – armature reaction – leakage reactance – synchronous reactance and impedance – experimental determination – phasor diagram – load characteristics.


Regulation of Synchronous Generator

Regulation by synchronous impedance method, M.M.F. method, Z.P.F. method and A.S.A. methods – salient pole alternators – two reaction analysis – experimental determination of Xd and Xq (Slip test) Phasor diagrams – Regulation of salient pole alternators.


Parallel Operation of Synchronous Generator Synchronizing alternators with infinite bus bars – synchronizing power torque – parallel operation and load sharing – Effect of change of excitation and mechanical power input. Analysis of short circuit current wave form – determination of sub-transient, transient and steady state reactances.

Electrical Machines III Notes (EM III)


Synchronous Motors – Principle of Operation

Theory of operation – phasor diagram – Variation of current and power factor with excitation – synchronous condenser – Mathematical analysis for power developed .


Power Circles

Excitation and power circles – hunting and its suppression – Methods of starting – synchronous induction motor.


Single Phase Motors

Single phase Motors: Single phase induction motor – Constructional features-Double revolving field theory –Equivalent Circuit – split-phase motors – Capacitor start capacitor run motors.


Special Motors

Principle & performance of A.C. Series motor-Universal motor – Principle of permanent magnet and reluctance motors.


  1. Electric Machines – by I.J.Nagrath & D.P.Kothari, Tata Mc Graw-Hill Publishers, 7th Edition 2005.
  2. Electrical Machines – by P.S. Bimbra, Khanna Publishers.


  1. The Performance and Design of A.C.Machines – by M.G.Say, ELBS and Ptiman & Sons.
  2. Electric Machinery – by A.E. Fitzgerald, C.Kingsley and S.Umans, Mc Graw-Hill Companies, 5th edition, 1990.
  3. Theory of Alternating Current Machinery by Langsdorf, Tata Mc Graw-Hill, 2nd edition.
  4. Electromachanics-III (Synchronous and single phase machines), S.Kamakashiah, Right Publishers

Note :- These notes are according to the r09 Syllabus book of JNTUH.In R13 ,8-units of R09 syllabus are combined into 5-units in r13 syllabus.Click here to check all the JNTU Syllabus books 

Frequently Asked Questions

Q1: What are synchronous machines?

A1: Machines which are principally utilized as altering current generators are known as synchronous machines. The electric power which is used by all the sectors of modern society are supplied by these machines. It is considered as important electromechanical energy converter. They are basically AC machines which have a field circuit supplied by external DC source.

Q2: What are the classification of synchronous machines?

A2: The synchronous machines are classified based on the type of prime movers employed. The classification is given as below

  1. Hydrogenerators which are driven by hydraulic turbines. (speed less than 1000 rpm)
  2. Turbogenerators which are driven by steam turbines (speed more than or equal to 1500 rpm)
  3. Engine driven generators which are IC engines (speed less than 1500 rpm)

Q3: What is the construction of synchronous machines?

A3: Construction of synchronous machine include,

  • Salient pole machines that have projecting pole with field windings (concentrated). Hydraulic turbines or diesel engines use this type of construction
  • Round rotor/cylindrical/non salient pole machines have smooth cylindrical rotor construction with distributed field winding in slots. Steam turbines utilize this type of rotor construction.

Q4: What are the different methods employed to minimize the harmonics in the induced waveform?

A4: Different methods employed to minimize the harmonics in the induced waveform are,

  • Larger length in air gap
  • Stator winding distribution
  • Fractional slot winding
  • Short chording
  • Skewing

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