LIVE Course for free

Rated by 1 million+ students
Get app now
JEE MAIN 2023
JEE MAIN 2023 TEST SERIES
NEET 2023 TEST SERIES
NEET 2023
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
35 views
in General by (59.9k points)
closed by
Eddy current loss of armature can be minimised ________.
1. by lamination
2. by distortion
3. by induced current
4. by folding

1 Answer

0 votes
by (110k points)
selected by
 
Best answer
Correct Answer - Option 1 : by lamination

Concept:

  • When an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to Faraday’s law of Electromagnetic induction.
  • Since the magnetic material is a conducting material, these EMF’s circulates current within the body of the material. These circulating currents are called Eddy currents. They are produced when the conductor experiences a changing magnetic field.
  • The process of lamination involves dividing the core into thin layers held together by insulating materials.
  • Due to lamination effective cross-section area of each layer reduces and hence the effective resistance increases.
  • As effective resistance increases, the eddy current losses will get decrease.

 

Mathematically, the eddy current loss is given by:

Pe = Ke Bm2. t2. f2. V Watts

Where;

K - coefficient of eddy current. Its value depends upon the nature of magnetic material

Bm - Maximum value of flux density in Wb/m2

t - Thickness of lamination in meters

f - Frequency of reversal of the magnetic field in Hz

V - Volume of magnetic material in m3

From the above formula, we conclude that the Eddy current loss is proportional to the square of the frequency.

Observation:

  • To minimize the eddy current loss we increases the resistance in the path of eddy current by laminating it.
  • Eddy current losses are directly proportional to area of armature or more precisely the path of motion.
  • In laminated armature eddy current losses are reduced to very less or '0' quantity. That is why armature of DC machines (either motor or generator) is laminated.

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...