Veer Surendra Sai University of Technology
Burla, Odisha
Subject: Electrical Machines-I
B.Tech., 3rd Semester
Branch : Electrical and Electronics Engineering
By
DR. RABINDRA KUMAR SAHU
Professor
Department of EEE, VSSUT, Burla
1
Introduction to DC Machines
By
DR. RABINDRA KUMAR SAHU
Professor
Department of EEE, VSSUT, Burla
2
Overview of Electrical Machines
Converters which are used continuously to convert
electrical input to mechanical output or vice-versa are
called
electric
machines.
An
electric
machine
is
therefore a link between electrical system and a
mechanical system.
Electric Machines are basically classified into two types
such as static machines and rotating machines.
Electrical supply is available in two forms such as DC
supply and AC supply.
Based on supply, the rotating machines are classified
into two types such as (i) DC machines, and (ii) AC
machines.
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10/14/2020
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Overview of DC Machines
DC machine is one of the most commonly used machine
for electro-mechanical energy conversion.
DC machines are classified into two types such as (i) DC
generators, and (ii) DC motors.
(i) DC generator
The machine which produces DC electrical power is known
as DC generator.
An
electric
generator
is
a
machine
which
converts
mechanical energy/power into electrical energy/power.
It
works
on
the
principle
of
Faraday’s
laws
of
electromagnetic induction, which states that “whenever a
conductor cuts the magnetic flux, an e.m.f. induced in it
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Applications:
DC
generators
are
suitable
for
many
applications – including general lighting, battery charging,
giving excitation to the alternators, series arc lighting etc.
(ii) DC Motor
The machine which produces mechanical power is known
as DC motor.
An electrical motor is a machine which converts electrical
energy/power into mechanical energy/power.
It works on the principle of Lorentz Law, which states that
“the current carrying conductor placed in a magnetic and
electric field experience a force”
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Applications: DC motors are suitable for many
applications – including conveyors, turntables, trolleys,
underground subway cars etc.
Any DC machine can act either as a generator or a
motor
A DC machine works as a DC generator when it is
driven by a prime mover.
The same machine works as a DC motor when
electrical energy is supplied to it.
Therefore,
the
constructional
features
of
a
DC
generator and DC motor are the same.
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