2.ppt

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

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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

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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

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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..

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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

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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

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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

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9EE402.3*Classification of Transformers Based on Location Contd..

Indoor transformerOutdoor transformer

Based on RatingLow rating transformerMedium rating transformerHigh rating transformer

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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

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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

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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*

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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

*

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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

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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

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9EE402.3Quiz

4) Transformers works on a.c. supply only

a) True

b) False

*

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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

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