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Recap
Can you recollect what we have learnt in lastperiod
Introduction to transformer
Working principle of transformer
Features of transformer
Step-up transformer
Step-down transfer
9EE402.3
9EE402.3
9EE402.3*Objective On completion of this period, you should be able to Classify transformers based on various factors such as number of phases, construction and function, no. of windings, type of cooling.
Based on location
Based on rating
Based on frequency
9EE402.3
9EE402.3*Classification of Transformers
Single Phase Transformers
Poly-Phase Transformers a) 2-phase Transformers b)3-Phase Transformers
Transformers are classified based upon Number of Phases
9EE402.3
9EE402.3*Classification of Transformers contd..Based on construction1. Core -type2. Shell -type3 Berry type
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9EE402.3*Based on Function
I) Power transformerSetup up transformerStep down transformer
II) Distribution transformer is always step down
Classification of Transformers contd..
9EE402.3
9EE402.3*Classification of Transformers contdIII) Instrument transformers
Current transformers
Potential transformers
IV) Welding transformers
Based on function
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9EE402.3*Classification of Transformers contdBased on Number of windings
Single winding transformer (Auto transformer)
Multi winding transformerSingle winding T/fMulti winding T/f
9EE402.3
9EE402.3*Classification of Transformers contd..Based on Type of cooling
I) Air cooled transformers
Natural air cooled transformer
Forced air cooled transformer
Induced air cooled transformer
9EE402.3
9EE402.3*Classification of TransformersTypes of cooling contd..II) Oil cooled transformerOil-filled natural or self cooled transformer
Oil-filled forced air cooled transformer
Oil-filled forced water cooled transformer
9EE402.3
9EE402.3*Classification of Transformers Based on Location Contd..
Indoor transformerOutdoor transformer
Based on RatingLow rating transformerMedium rating transformerHigh rating transformer
9EE402.3
9EE402.3*Classification Of Transformers contd..Based on FrequencyLow frequency or power frequency or audio frequency frequency 50 Hz
High frequency transformer, pulse transformer, radio frequency etc
9EE402.3
9EE402.3*What happens when a transformer is connected to aDC supply ?
The flux produced by DC supply does not vary but remains constant in magnitudeAs flux remains constant no e.m.f is induced in the primary and secondary
Why Transformer Works on AC Supply only ?
Electro magnetic induction
9EE402.3
9EE402.3
As there is no self induced e.m.f in the primary winding to oppose the applied voltage
A heavy current will flow through the primary winding
And this large current will result in the damage of the winding*
9EE402.3
9EE402.3*Summarywe have discussed about
Classification of Transformer based on various factors like Number of phases
Construction
Function
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9EE402.3Summary contd..
Number of windingType of cooling LocationRating FrequencyReasons for working transformer on a.c. supply only
*
9EE402.3
1) Based on construction, transformers are classified into
a) Core type , Shell type, Berry type
b) Single phase, Three phase
c) Either (a) or (b)
9EE402.3Quiz
9EE402.3
9EE402.3Quiz* 2) Based on No. of phases transformers are classified into
a) Core type
b) Shell type
c) Single phase and Poly phase
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9EE402.3*Quiz 3) Distribution transformers are always step-down transformers
a) True
b) False
9EE402.3
9EE402.3Quiz
4) Transformers works on a.c. supply only
a) True
b) False
*
9EE402.3
9EE402.3*Frequently Asked Questions 1) Classify the transformers based on various factors
2) Give reasons for working of transformers on a.c. supply only
9EE402.3