This document contains lecture notes on the fundamentals of electrical machine design from the EE-1352 ELECTRICAL MACHINE DESIGN course. It defines electrical machine design as the creative physical realization of theoretical concepts to produce machines that perform specified tasks with optimum economy and efficiency. The notes discuss basic considerations in developing a design including the design base, specifications, design transfer, and information updating. It also outlines major considerations like lower cost, durability, and meeting performance criteria, as well as limitations in design such as magnetic saturation, temperature rise, insulation, and customer specifications. Finally, it describes the basic structure of electrical machines including the magnetic, electric, dielectric, thermal, and mechanical circuits.

1. EE-1352 ELECTRICAL MACHINE DESIGN
TEXT BOOK
1. Sawhney, A.K., “A Course in Electrical Machine Design”, 6thEdition,
Dhanpat Rai and Sons, 2006
REFERENCES
1. Agarwal, R.K., “Principles of Electrical Machine Design”, S.K.Kataria
and Sons, 2002
2. Mittle,V.N. and Mittle, A., “Design of Electrical Machines”, Standard
Publications and Distributors, 2002
P.Rameshbabu/saranathan/EEE Dept. 1

2. UNIT-I
FUNDAMENTAL CONCEPTS
P.Rameshbabu/saranathan/EEE Dept. 2

3. What is meant by electrical machine design?
 Design may be defined as a creative physical
realization of theoretical concepts.
 Engineering design is application of science,
technology and invention to produce machines
to perform specified tasks with optimum
economy and efficiency.
P.Rameshbabu/saranathan/EEE Dept. 3

4. Basic considerations to develop a design are
1.Design base
 matching the existing experience with R and D
 bringing in the latest material technology
 limitations in design
 convenience in production line and
transportation
 working safety and reliability
 maintenance and repair
 environmental conditions
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5. 2. Specification
meeting with the customer’s requirements
 guarantees
 satisfy the national and international standards
3. Design transfer
 Transfer of design to factory foreman i.e. drawings,
processes instructions ,job flow, meeting the delivery
schedule.
4. Information updating
Technical journals, R and D papers and reports,
interaction in meetings, seminars and conferences
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6. Major considerations to develop a design are
The design should be carried out based on the given
specification using available materials economically
and to achieve the following
1. Lower cost
2. Durability
3. Conformity with performance criteria as laid
down in specifications
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7. LIMITATIONS IN DESIGN
1. Saturation of magnetic parts
Increased core losses and excitation at higher flux density
resulting in higher cost for the field system.
2. Temperature rise
 Increased temperature rise under higher output weakens
the insulation and affects the life of machine.
2. Insulation
It should be able to withstand the electrical, mechanical and
thermal stresses which are produced in the machine.
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8. 4. Mechanical strength
Specially in turbo machine due to large size and high speed.
5.Efficiency
 If high efficiency is the aim, the machine becomes costly, for
lower efficiency higher running cost and temperature rise
with associated problems. cy
6. Customer’s specifications
Imposes limitations to identify criterion for best design
7. Commutation
In DC machine output is limited because of
commutation problem
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9. 8. Power factor
Power factor imposes a limitation specially in case of
3 phase induction motor.
9.Standard specification
 Specification is biggest strain on the design because
cy the
both the manufacturer as well as the consumer cannot
get away from them without satisfying them.
P.Rameshbabu/saranathan/EEE Dept. 9

10. Basic structure of electrical machine
1. Magnetic circuit : core ,yoke, air gap etc.
2. Electric circuit : stator, rotor winding and
transformer winding
cy
3. Dielectric circuit : insulation
4. Thermal circuit : heating and cooling medium
5. Mechanical parts : frame, bearings and shaft
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11. P.Rameshbabu/saranathan/EEE Dept. 11

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