This is the presentation I gave during my seventh semester of Electrical Engineering course at NIT Durgapur. It is here for you guys. Make life easier. Cheers! For more information mail me: sdey.enteract@gmail.com

1. Presented by :
Subrata Dey
Roll no.: 14/EE/79
NIT Durgapur
Design and Development of a
Transformer

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 Contents
Introduction
Motivation
Objective
History of Development
Design Specifiactions
Future Scope & Conclusion

3. 1. Introduction
What isTransformer ?
 Pre-requisite for Design
o Electrical properties
o Knoweldge of materials
o Economics
3

4. 2. Motivation
 Importance ofTransformers in Power
Systems
 Incident of sabotage(California)
4

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3. Objective
Cost
Durability
Efficiency and losses

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4. History of Development ofTransformer
 Inventors : Ottó Bláthy, Miksa Déri, Károly
Zipernowsky
ZBDTransformer(1878) First Single phaseTransformer(1886)

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5. Design Specifications ofTransformer
 Design ofYoke
o The area of yoke is taken as 15-20% higher than limb.
o The yoke cross-section with step downwards is
generally used.
Step downward cross-section

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Window Dimension
o
𝑡𝑜𝑡𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟 𝑎𝑟𝑒𝑎
𝑤𝑖𝑛𝑑𝑜𝑤 𝑠𝑝𝑎𝑐𝑒 𝑓𝑎𝑐𝑡𝑜𝑟
=Area of window
o
𝑡𝑜𝑡𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟 𝑎𝑟𝑒𝑎
𝑡𝑜𝑡𝑎𝑙 𝑤𝑖𝑛𝑑𝑜𝑤 𝑎𝑟𝑒𝑎
= window space factor
Wsp=
10
30+KV
Self inductance, L=
𝜇𝐴𝑁2
𝑙

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 Design of insulation
o Electrical considerations
Depends on voltages that appears in the different
parts of transformer. Impulse voltage test is done to check
the insulation.
o Mechanical Considerations
Design should be such that it minimizes the hoop
and compressive stress.

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Selection of windings
o Shape of the core

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 Choice of flux density
o Depends on core area
o Service conditions e.g. in distribution
transformer it is kept very low.
Typical values for distribution transformer is 1.1 to
1.35 wb/m2

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 Design of core
o Rectangular cores: For core type distribution transformers and small
power transformers
o Square:To reduce the waste of materials (Fig. a)
o Stepped cores: For larger transformer cruciform cores are used(Fig.
b)
b=.53d

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Referring to the Fig. (a)
Let, stacking factor= .9
Gross core area= (.71d)2 = .5 d2
Net core area= .45 d2
Ratio of net core area to area of circumscribing circle= .58
Referring to the Fig. (b)
Gross core area= ab + b(a-b) =.618 d2
Take, a= d cosθ ; b = d sinθ
Hence, Gross core area = d2(sin2θ − sin2θ)
For maximum area, θ= 31° 45′
Ratio of net core area to area of circumscribing circle= .71
Net core area= .56 d2
Length of mean turn= π × Diameter

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6. Conclusion and Future Scope
o Design and development of transformer is costly and time
consuming.
o Hence monitoring is essential after installation.
o In order to prevent the incident of sabotage of transformer
bullet-proof tank should be designed.

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7. References
o Wikipedia
o SPXTransformer Solution,Inc.
o ABB-https://www.abb.com/transformers
o Electrical Machine Design by A.K.Sawhney

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Thank you

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Questions ?