What is a Transformer?
Transformer is a device which:
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Transfer Electrical power from one electrical circuit to another Electrical circuit.
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It’s working without changing the frequency.
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Work through on electric induction.
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When, both circuits take effect of mutual induction.
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Can’t step up or step down the level of DC voltage or DC Current.
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Can step up or step down the level of AC voltage or AC Current.
Construction of a Transformer

1 |
Oil filter valve |
17 |
Oil drain valve |
2 |
Conservator |
18 |
Jacking boss |
3 |
Buchholz relay |
19 |
Stopper |
4 |
Oil filter valve |
20 |
Foundation bolt |
5 |
Pressure-relief vent |
21 |
Grounding terminal |
6 |
High-voltage bushing |
22 |
Skid base |
7 |
Low-voltage bushing |
23 |
Coil |
8 |
Suspension lug |
24 |
Coil pressure plate |
9 |
B C T Terminal |
25 |
Core |
10 |
Tank |
26 |
Terminal box for protective devices |
11 |
De-energized tap changer |
27 |
Rating plate |
12 |
Tap changer handle |
28 |
Dial thermometer |
13 |
Fastener for core and coil |
29 |
Radiator |
14 |
Lifting hook for core and coil |
30 |
Manhole |
15 |
End frame |
31 |
Lifting hook |
16 |
Coil pressure bolt |
32 |
Dial type oil level gauge |
Types of Transformers
There are two basic Types of Transformers
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Single Phase Transformer
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Three Phase Transformer
Below are the more types of transformer derived via different functions and operation etc.
Types of Transformers w.r.t Cores
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Core Type Transformer
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Shell Type Transformer
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Berry Type Transformer
Types of Transformer w.r.t uses
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Large Power Transformer
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Distribution Transformer
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Small Power Transformer
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Sign Lighting Transformer
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Control & Signalling Transformer
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Gaseous Discharge Lamp Transformer
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Bell Ringing Transformer
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Instrument Transformer
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Constant Current Transformer
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Series Transformer for Street Lighting
Types of Transformer w.r.t Cooling
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Self Air Cooled or Dry Type Transformer
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Air Blast-Cooled Dry Type
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Oil Immersed, Self Cooled (OISC) or ONAN (Oil natural, Air natural)
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Oil Immersed, Combination of Self Cooled and Air blast (ONAN)
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Oil Immersed, Water Cooled (OW)
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Oil Immersed, Forced Oil Cooled
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Oil Immersed, Combination of Self Cooled and Water Cooled (ONAN+OW)
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Oil Forced, Air forced Cooled (OFAC)
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Forced Oil, Water Cooled (FOWC)
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Forced Oil, Self Cooled (OFAN)
Types of Instrument Transformer
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Current Transformer
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Potential Transformer
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Constant Current Transformer
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Rotating Core Transformer or Induction regulator
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Auto Transformer
Operating & Working Principle of a Transformer
Transformer is a static device (and doesn’t contain on rotating parts, hence no friction losses), which convert electrical power from one circuit to another without changing its frequency. it Step up (or Step down) the level of AC Voltage and Current.
Transformer works on the principle of mutual induction of two coils or Faraday Law’s Of Electromagnetic induction. When current in the primary coil is changed the flux linked to the secondary coil also changes. Consequently an EMF is induced in the secondary coil due to Faraday law’s of electromagnetic induction.
The transformer is based on two principles: first, that an electric current can produce a magnetic field (electromagnetism), and, second that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.
