7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 1/25

ELECTRO MECHANICAL ENERGY

CONVERSION

Electrical Machines

U M Rao

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 2/25

Electrical Energy  Mechanical Energy To 

No direct connection between

electrical system To Mechanical System

EMEC

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 3/25

EMEC

EMEC –  REVERSABLE PROCESS 

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 4/25

EMEC

MAGNETIC ENERGY 

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 5/25

MAGNETIC ENERGY

MEDIA FOR ENERGY TRANSFER IS THROUGH

MAGNETIC FLUX LINES 

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 6/25

Concept of Flux lines

• This concept was first introduced by

Michael Faraday as a means of

visualizing the distribution anddensity of magnetic field.

• This concept helps us in

understanding the physical behavior

of many electrical concepts.

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 7/25

  Faraday’s concept of lines of force or flux

lines was rejected by his peers as they assumed

that electric charge is responsible for attraction

or repulsion. Physicist James Clerk Maxwell

accepted the concept of lines of force and put

Faraday's ideas into mathematical form, thus

giving birth to modern field theory.

Concept of Flux lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 8/25

11/16/2014 8

Concept of Flux lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 9/25

911/16/2014

The direction of a magnetic flux line  at anypoint in a non-magnetic field, such as air, isthat of the NORTH-SEEKING pole of a compassneedle.

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 10/25

1011/16/2014

• Each magnetic flux line forms a closed

loop 

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 11/25

1111/16/2014

• Lines of magnetic flux never intersect

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 12/25

1211/16/2014

• Lines of magnetic flux are like stretched

cords and always try to shorten.

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 13/25

1311/16/2014

Lines of magnetic flux which are in parallel

in the same direction repel each other.

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 14/25

1411/16/2014

Lines of magnetic flux which are in parallel

and with opposite direction attract each other.

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 15/25

1511/16/2014

Characteristics of

Magnetic Flux Lines

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 16/25

THE ABOVE FOUR SLIDESDEMONSTRATE

CONVERSION OFMAGNETIC ENERGY

TO

MECHANICAL ENERGY.

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 17/25

Electro Magnetism

• First discovery was made by Danish

physicist Hans Christian Oersted in

the year 1820.

•

  He discovered that,“A piece of wire carrying electric

current behaves as a magnet”or

“The electric current flowing in awire can produce magnetic field in thespace surrounding the wire”  

Origin of Electromagnetism

Ch i i f

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 18/25

1811/16/2014

Flux generation by current carrying conductor

Characteristics of

Electro Magnetism

Ch i i f

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 19/25

• If a coil is wound on a steel rod and if current

is passed through the coil, then the steel rod

behaves like a magnet. This rod with coil is

known as Solenoid.

Characteristics of

Electro Magnetism

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 20/25

• If the solenoid is gripped with right hand, with

the fingers pointing the direction of current,

then the thumb indicates the NORTH POLE of

that magnet.

Characteristics of

Electro Magnetism

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 21/25

• As current flowing in each turn of the Solenoid

is contributing to flux lines, the total flux is

proportional to number of turns and current

flowing through the turns, thus:

Flux α Number of turns X Current 

Characteristics of

Electro Magnetism

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 22/25

Magnetic Circuit

Electric Circuit  Magnetic Circuit 

(Volts) (Amperes) 

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 23/25

Magnetic Circuit

∅ ∝ (. )() 

∅ ∝ () 

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 24/25

Magneto Motive Force (MMF)

• In an Electric Circuit “CURRENT” flows because

of ELECTRO MOTIVE FORCE (EMF).

By analogy• In a Magnetic Circuit “FLUX” flows because of

MAGNETO MOTIVE FORCE (MMF).

7/26/2019 EMEC 1 5th Aug 2013

http://slidepdf.com/reader/full/emec-1-5th-aug-2013 25/25

Electro-Magnetic Flux

• Flux and Magnetic field strengths inthe magnetic core depends on:

Magnetic Motive Force.

Number of turns

Current flowing through the turns

 Length of flux path.Core Material of Magnetic circuit.