1. • Made By : Shaikh Zulkar, Shaikh
Uvesh, Khan Asif.
• Submitted To: Ms.Krupul
Dhimmar
2. Transformers
“ A transformer is a static device
which is use to convert high
alternatic voltage to a low
alternatic voltage and vice versa,
keeping the frequency same."
3. Principle Of Operation
“Transformer works on the principle of
mutual induction of two coils.
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."
5. Autotransformers
“ An autotransformer (som etimes called
auto step down transformer) is an
electrical transformer with only one
winding.
In an autotransformer, portions of the
same winding act as both the primary
and secondary si des of the transformer."
6. Theory of Autotransformer
🠶 N1=primary turn(1-3)
🠶 N2=secondary turn(2-3)
🠶 I1=primary current
🠶 I2=secondary current
🠶 V1=primary voltage
🠶 V2=secondary voltage
From Figure i we get:
7. Cont.….
(I/P=O/P)
OUTPUT
The primary and secondary
windings of an autotransformer
are
Connected magnetically as well as
electrically.
So the power transferred primary
to secondary inductively as well as
conductively.
9. Step Up Auto-Transformer
“ An autotransformer in which Ns>Np is called a
step up autotransformer. A step up
autotransformer is a transformer which
converts low alternatic voltage to high
alternatic voltage."
10. Step Down Auto-Transformer
“ A n autotransformer in which
Np>Ns is called a step down
autotransformer. A step down
autotransformer is a transformer
which converts high alternating
voltage to low alternating voltage."
11. AdvantagesOfAutotransformers
• An autotransformer requires less Cu than a two-winding transformer
of similar rating.
• An autotransformer operates at a higher efficiency than a two-winding
transformer of similar rating.
• An autotransformer has better voltage regulation than a two-winding
transformer of the same rating.
• An autotransformer has smaller size than a two-winding transformer
of the same rating.
• An autotransformer requires smaller exciting current than a two-winding
transformer of the same rating.
