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EEE-ND-2020-EE 2251-Electrical Machines – I-806884291-X60497(EE2251)

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Electronics and communication

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Academic year: 2018/2019
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Pandit Lakhmi Chand State University of Performing and Visual Arts
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60497 Reg. No. :

Question Paper Code : X 6 0497

B.E./B. DEgREE ExamiNaTioNs, NOV./DEC. 2020

Fourth semester

Time : Three hours maximum : 100 marks 1. clearly define the mmF and EmF.

  1. Which equivalent circuit parameters can be determined from the open-circuit test on a transformer?
  2. The emf per turn for a single-phase 2200/220 V, 50 hz transformer is 11 V. calculate the number of primary and secondary turns.
  3. Draw the power low diagram for motor and generator operation.
  4. in a magnetic circuit with a small air gap, in which part the maximum energy is stored and why?
  5. What is meant by spp? What is its significance?
  6. Enumerate the advantages of using short-pitched winding in a synchronous machine.
  7. list the factors involved in the voltage build up of a shunt generator.
  8. Why the external characteristics of a Dc shunt generator is more drooping than that of a separately excited generator?

answer all questions paRT – a (10×2=20 Marks) 2. What are the core losses and how can this loss be minimized?

Electrical and Electronics Engineering

EE 2251/EE 42/EE 1251 a/10133 EE402/080280003 – ElEcTRical machiNEs – i

(Common to PTEE2251/10133EE402 (Regulations 2008/2010) For B. (Part Time)-ThirdEngineering-Regulations 2009/2010) Semester-Electrical and Electronics

paRT – B (5×16=80 Marks) 11. a) i) Define inductance of a coil. (4) ii) For the magnetic circuit shown in Fig. 11 (a) (ii) determine the currentrequired to establish a flux density of 0 T in the air gap. (12)

Figure 11 (a) (ii) (oR) b) i) Define permeability of a magnetic material and the factors on which itdepends. (4) ii) Explain the operation of a magnetic circuit when a. current is applied to the coil wound on iron core. Draw the B-h curve and obtain an expressionfor hysteresis loss. (12) 12. a) i) Describe the construction and principle of operation of single phasetransformer. (8) ii) Derive an expression for maximum efficiency of a transformer. (8) (oR) b) a 500 kVa transformer has 95% efficiency at full load and also at 60% of full load both at upf. i) separate out the transformer losses. ii) Determine the transformer efficiency at 75% full load, upf. 13. a) i) Describe the flow of energy in electromechanical devices. (6) ii) Discuss about the ‘field energy’ and ‘coenergy’ in magnetic system. (4) iii) The magnetic flux density on the surface of an iron face is 1 T which isa typical saturation level value for ferromagnetic material. Find the force density on the iron face. (6) (oR)

X 6 0497 -2- 60497

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EEE-ND-2020-EE 2251-Electrical Machines – I-806884291-X60497(EE2251)

Course: Electronics and communication

704 Documents
Students shared 704 documents in this course

University: Pandit Lakhmi Chand State University of Performing and Visual Arts

Was this document helpful?
*60497* Reg. No. :
Question Paper Code : X 60497
B.E./B.Tech. DEgREE ExamiNaTioNs, NOV./DEC. 2020
Fourth semester
Time : Three hours maximum : 100 marks
1. clearly define the mmF and EmF.
3. Which equivalent circuit parameters can be determined from the open-circuit test
on a transformer ?
4. The emf per turn for a single-phase 2200/220 V, 50 hz transformer is 11 V. calculate
the number of primary and secondary turns.
5. Draw the power low diagram for motor and generator operation.
6. in a magnetic circuit with a small air gap, in which part the maximum energy is
stored and why ?
7. What is meant by spp ? What is its significance ?
8. Enumerate the advantages of using short-pitched winding in a synchronous
machine.
9. list the factors involved in the voltage build up of a shunt generator.
10. Why the external characteristics of a Dc shunt generator is more drooping than
that of a separately excited generator ?
answer all questions
paRT – a (10×2=20 Marks)
2. What are the core losses and how can this loss be minimized ?
Electrical and Electronics Engineering
EE 2251/EE 42/EE 1251 a/10133 EE402/080280003 – ElEcTRical machiNEs – i
(Regulations 2008/2010)
(Common to PTEE2251/10133EE402 For B.E. (Part
Time)-Third Semester-Electrical and Electronics
Engineering-Regulations 2009/2010)

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