An autotransformer is
an electrical transformer
with only one winding.
In an autotransformer portion
of the same winding act as
both primary and secondary
sides of the transformer.
2. WHAT IS AUTOTRANSFORMER❓
• An autotransformer is
an electrical transformer
with only one winding.
In an autotransformer
portion
of the same winding act
as
both primary and
secondary
4. STEP UP AUTO-TRANSFORMER
• An autotransformer in which
Ns>Np is called as step up
Autotransformer. A step up
autotransformer is a transformer
which converts the low alternating
voltage to high alternating voltage
5. STEP DOWN AUTO- TRANSFORMER
• An autotransformer in which
Np>Ns is called as step down
autotransformer. A step down
autotransformer is a transformer
which converts high alternating
voltage to low alternating voltage
6. WORKING OF AUTO-TRANSFORMER
As compared to two winding transformers as shown in figure ,
autotransformers has a single winding. When an alternating supply
is given to the primary circuit , because of Faraday’s law of
electromagnetic induction, an emf is induced in the primary circuit.
Since the magnetic field is alternating in nature and conductors are
stationary ,the induced emf in the primary winding produces a flux ,
which is called as primary winding flux. This flux links the secondary
winding and induces an emf on secondary winding due to mutual
induction. Hence emf is transferred in the secondary winding. Based
on a number of turns on the secondary side, the magnitude of
induced emf is determined.
7. ADVANTAGES OF AUTOTRANSFORMER
• An autotransformer requires less Cu than a two
winding transformer of similar rating.
• An autotransformer operates at higher efficiency than a
two
winding transformer of similar rating.
• An autotransformer has better voltage regulations than
a two winding transformer of same rating.
• An autotransformer has smaller size than a two winding
transformer of same rating.
• An autotransformer requires small exciting current than a
two winding
8. DISADVANTAGES OF AUTOTRANSFORMER
•There is a direct connection between primary and
secondary
Therefore the output is no longer D.C. Isolated from
the input
•An autotransformer is not safe for stepping down a
high voltage to a low voltage
•The short circuit current is much larger than for two
winding transformer of the same rating . So that a
short circuited secondary causes part of the
9. APPLICATIONS OF AUTOTRANSFORMER
• Autotransformer are used to compensate for Voltage drop in
transmission
and distribution lines. When used for these purpose they are known
as booster transformer.
• Autotransformer are used for reducing the voltage supplied to a.c
motors
during starting period.
• Autotransformer are used for continuisly continuously variable
supply.
• In control equipment for 1-phase and 3-phase electrical locomotives
10. CONCLUSION
•To above study we conclude that
autotransformer has less amount of
Cu loss required, high efficiency,
Possible to get smooth and
continuous
variation voltage.
