Electrical Machines II Syllabus for JNTU Kakinada
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY,
II Year B.Tech EEE II-Sem T P C
4+1* 0 4
ELECTRICAL MACHINES – II
As an extension of Electrical machines I course this subject facilitates to study of the performance of
Transformers and Induction motors which are the major part of industrial drives and agricultural pump
UNIT-I Single Phase Transformers – Construction & Operation
Single phase transformers-types – constructional details-minimization of hystersis and eddy current
losses-emf equation – operation on no load and on load – phasor diagrams
UNIT-II Single Phase Transformers – Performance
Equivalent circuit – losses and efficiency-regulation. All day efficiency – effect of variations of frequency &
supply voltage on iron losses.
UNIT-III Testing of Single Phase Transformer and Autotransformer
OC and SC tests – Sumpner’s test – predetermination of efficiency and regulation-separation of losses
test-parallel operation with equal and unequal voltage ratios – auto transformers-equivalent circuit –
comparison with two winding transformers.
UNIT-IV Polyphase Transformers
Polyphase transformers – Polyphase connections – Y/Y, Y/D, D/Y, D/D and open D, Third harmonics in
phase voltages-three winding transformers-tertiary windings-determination of Zp, Zs and Zt transients in
switching – off load and on load tap changing; Scott connection.
UNIT-V Polyphase Induction Motors
Polyphase induction motors-construction details of cage and wound rotor machines-production of a
rotating magnetic field – principle of operation – rotor emf and rotor frequency – rotor reactance, rotor
current and pf at standstill and during operation.
UNIT-VI Characteristics of Induction Motors
Rotor power input, rotor copper loss and mechanical power developed and their inter relation-torque
equation-deduction from torque equation – expressions for maximum torque and starting torque – torque
slip characteristic – double cage and deep bar rotors – equivalent circuit – phasor diagram – crawling and
UNIT-VII Circle Diagram of Induction Motors
Circle diagram-no load and blocked rotor tests-predetermination of performance-methods of starting and
starting current and torque calculations
UNIT-VIII Speed Control Methods
Speed control-change of frequency; change of poles and methods of consequent poles; cascade
connection. injection of an emf into rotor circuit (qualitative treatment only)-induction generator-principle of
1. Electric machinery – A.E. Fitzgerald, C.Kingsley and S.Umans, Mc Graw Hill
Companies, 5th edition
2. Electrical machines-PS Bhimbra, Khanna Publishers.
1. Performance and Design of AC Machines by MG.Say, BPB Publishers
2. Theory of Alternating Current Machinery- by Langsdorf, Tata McGraw-Hill Companies, 2nd
3. Electric Machines –by I.J.Nagrath & D.P.Kothari,Tata Mc Graw Hill, 7th Edition.2005
4. Electromechanics-II (transformers and induction motors) S. Kamakashaiah Hitech publishers.