ELECTRICAL MACHINE DESIGN (18EE55)

 ELECTRICAL MACHINE DESIGN

Course Code 18EE55 CIE Marks 40
Number of Lecture Hours/Week (L:T:P) 3:0:0 SEE Marks 60
Credits 03 Exam Hours 03

Course Learning Objectives:

· To discuss design factors, limitations in design and modern trends in design and manufacturing of
electrical machines.
· To discuss the properties of electrical, magnetic and insulating materials used in the design of
electrical machines.
· To derive the output equation of DC machine, single phase, three phase transformers, induction
motor and synchronous machines.
· To discuss the selection of specific loadings, for various machines.
· To discuss separation of main dimensions for different electrical machines
· To discuss design of field windings for DC machines and synchronous machines. To evaluate the
performance parameters of transformer, induction motor.
· To design of cooling tubes for the transformer for a given temperature rise.
· To explain design of rotor of squirrel cage rotor and slip ring rotor.
· To define short circuit ratio and discuss its effect on machine performance.

Module-1

Fundamental Aspects of Electrical Machine Design: Design of Machines, Design Factors,
Limitations in design, Modern Trends in design, manufacturing Techniques.
Electrical Engineering Materials: Desirabilities of Conducting Materials, Comparison of Aluminium and
Copper wires. Ferromagnetic Materials: Soft Magnetic materials – Solid Core Materials, Electrical Sheet
and Strip, Cold Rolled Grain Oriented Steel. Insulating Materials: Desirable Properties, Temperature Rise
and Insulating Materials, Classification of Insulating materials based on Thermal Consideration.

Module-2

Design of DC Machines: Output Equation, Choice of Specific Loadings and Choice of Number
of Poles, Main Dimensions of armature, Design of Armature Slot Dimensions, Commutator and Brushes.
Estimation of Ampere Turns for the Magnetic Circuit. Dimensions of Yoke, Main Pole and Air Gap. Design
of Shunt and Series Field Windings.

 

Module-3

Design of Transformers: Output Equations of Single Phase and Three Phase Transformers, Choice of
Specific Loadings, Expression for Volts/Turn, Determination of Main Dimensions of
the Core, Estimation of Number of Turns and Conductor Cross Sectional area of Primary and Secondary
Windings, No Load Current. Expression for the Leakage Reactance of core type transformer with
concentric coils, and calculation of Voltage Regulation. Design of Tank and Cooling (Round and
Rectangular) Tubes.

 

Module-4

Design of Three Phase Induction Motors: Output Equation, Choice of Specific Loadings, Main
Dimensions of Stator. Design of stator slots and Winding, Choice of Length Air Gap, Estimation of Number
of Slots for Squirrel Cage Rotor. Design of Rotor Bars and End Ring. Design of Slip Ring rotor. Estimation
of No Load Current and Leakage Reactance.

 

Module-5

Design of Three Phase Synchronous Machines: Output Equation, Choice of Specific Loadings, Short
Circuit Ratio, Main Dimensions of Stator. Design of stator slots and Winding. Design of
Salient and non- salient Pole Rotors. Magnetic Circuit and Field Winding.

 

Course Outcomes: At the end of the course the student will be able to:

· Identify and list, limitations, modern trends in design, manufacturing of electrical machines and
properties of materials used in the electrical machines.
· Derive the output equation of DC machine, discuss selection of specific loadings and magnetic
circuits of DC machines, design the field windings of DC machine, and design stator and rotor
circuits of a DC machine.
· Derive the output equations of transformer, discuss selection of specific loadings, estimate the
number of cooling tubes, no load current and leakage reactance of core type transformer.
· Develop the output equation of induction motor, discuss selection of specific loadings and magnetic
circuits of induction motor, design stator and rotor circuits of a induction motor.
· Formulate the output equation of alternator, design the field windings of Synchronous machine,
discuss short circuit ratio and its effects on performance of synchronous machines, design salient pole
and non-salient pole alternators for given specifications.

Question paper pattern:

· The question paper will have ten questions.
· Each full question is for 20 marks.
· There will be 2 full questions (with a maximum of three sub questions in one full question)
from each module.
· Each full question with sub questions will cover the contents under a module.
· Students will have to answer 5 full questions, selecting one full question from each module.

Text Book

1 A course in Electrical Machine
design
A.K.Sawhney DhanpatRai 6th Edition, 2013

Reference Books

1 Performance and Design of
Alternating
Current Machines
M.G. Say CBS
Publisher
3rd Edition, 2002
2 Design Data Handbook A. Sanmugasundaram
Et al
New Age
International
1st Edition, 2011