WITH EFFECT FROM THE ACADEMIC YEAR 2012 - 2013
EE 302
ELECTRICAL MACHINERY - II
Instruction 4/1 Periods per week
Duration of University Examination 3 Hours
University Examination 75 Marks
Sessional 25 Marks
UNIT-I
Parallel operation of Single phase Transformer and load sharing. Insulation of Windings and terminals. Cooling arrangement in Transformers. Testing of Transformers -Routine Tests and Special tests -Measurement of Voltage ratio and check for voltage vector relationship. Measurement of No- load loss and current. Measurement of Insulation resistance. Maintenance of Transformers.
UNIT-II
Poly-phase Transformer Connections ,Choice of Transformer Connections, Third harmonic voltages -Phase Conversion -3phase to 2-phase transformation -Scott connection. Constructional features of three-phase transformers, tertiary winding, parallel operation of transformer, Auto Transformer -Comparison with two winding transformers- Conversion of two winding transformer to auto transformer. Tap changer on transformers, No-load tap changer, On-load tap changer.
UNIT-III
Three-phase Induction Motor -Constructional features –Rotating Magnetic field theory —Principle of operation of squirrel cage and slip ring motors -Vector Diagram , Equivalent circuit -Expression for torque- Starting torque, Maximum torque -Slip/Torque characteristics - Performance characteristics -Equivalent circuits from test –Current loci circle diagram - Predetermination of characteristics of Induction Motors .
UNIT-IV
Starting methods of Induction motors .Modes of operation, torque and power limits of Induction motors-Speed control methods -Resistance Control, Voltage control, pole changing, Cascading, variable frequency
3 4
control- Slip power recovery schemes Kramer drive. Scherbius drive-Double cage Induction motors. Induction generator
UNIT-V
Unbalanced Operation: Voltage Unbalance -Unbalanced Operation of 3-phase Induction Motor -Per Phase Equivalent Circuits -Single Phasing-Unbalanced Operation of 3-Phase Transformers –Single phase load on Three phase transformers Single Phasing in 3 phase transformers- Delta / Star and Star/Delta transformers.
Suggested Reading:
- 1.I.J. Nagarath, D.P.Kothari, Electrical Machines. 4th Edition Tata McGraw Hill, 2010.
- 2.J.B. Gupta, Theory and Performance of Electrical Machines, S.K. Kataria. & Sons, 2003.
- 3.P.S. Bimbhra, Generalised theory of Electrical Machines, Khanna Publishers Fifth Edition 1995
- 4.M.G.Say, The performance and Design of A.C. Machines- Pitman, 1985.
- 5.Fitzerald A E and Kingzley, Electrical Machines, .3rd Edition.