Download AKTU B-Tech 4th Sem 2015-16 EEE 401 Electromechanical Energy Conversion I Question Paper

Printed Pages: 4

EEE-401

(Following Paper ID and Roll No. to be filled in your Answer Books)

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Paper ID : 121405 Roll No.

B. TECH.

Theory Examination (Semester-IV) 2015-16

ELECTROMECHANICAL ENERGY CONVERSION-I

Time : 3 Hours Max. Marks : 100

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Section-A

1. Attempt all parts. All parts carry equal marks. Write answer on each part in short. (2×10=20)
   1. What are the basic role of "Dummy Coils" in D.C. machines ?
   2. Explain the introduction of "electro-mechanical energy conversion principles."
   3. Explain the interpole and compesating winding of D.C. Machines.
   4. Explain the commutation process in D.C. machines.

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   5. Enlist any five applications of D.C. Machines.
   6. Enlist any five applications of 3 phase transformers.
   7. What are the basic difference between auto-transformers and 2-wdg transformers ?
   8. Define "Phasor group of 3 phase transformers.”
   9. Define open crcuit and short crcuit test of 1 phase transformers.

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   10. Explain the all day efficiency of transformers.

Section-B

2. Attempt any 5 questions from this section. (10×5=50)
   1. Discuss the armature reaction of D.C. machines: What are the advantages and dis advantages of armature reaction in D.C. machines ? Explain in detail.
   2. Write a short notes on the following :
      1. Open delta connection of 3 phase transformers.

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      2. Excitation phenomenon in 3 phase transformers.
   3. Discuss the harmonics in 3 phase transformers. What are the merits and demerits of harmonics in 3 phase transformers.
   4. Discuss the constructional details and working principle of three winding transformers. What are the limitations and significances of ths transformers.
   5. Write a short notes on the parallel operations of 3 phase transformers.

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   6. Discuss the ward Lenonard method for speed control D.C. machines working as motoring node.
   7. What do you mean by effeciency and voltage regulation of 1 phase transformers ? Also mention the applications and limitations of 1 phase transformers.
   8. Write a short notes on the following :
      1. 3 phase to 2 phase connection of transforms.
      2. 3 phase to 6 phase connection of transforms.

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Section-C

3. Attempt any 2 questions from this section. (15×2=30)
   1. Consider the equivalent circuit diagram of D.C. machine as shown in Fig-1.
      + Ra = 0.5 O Rsh = 50 O
      Rs = 2O +
      

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      V_t = 440 V
      E_b
      Fig. 1
      Given data : - Brush drop = 2V / per brush
      (1) Interpole winding drop = 0.5V
      

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      (11) Compensating winding drop = 0.25V
      What should be the speed of D.C. machine working as motoring mode ?
      What should be the speed of D.C. machine working as gererating mode ?
   2. Consider the equivalent circuit diagram of 1 phase transformes as shown in Fig 2.
      I₁
      

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      +
      R₁ jX₁ R₂ jx₂
      V₁
      Rc jXm
      Open
      

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      ?
      1:2
      Fig. 2
      Given data :
      R₁ = 0.50 O
      

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      R₂ = 0.25 O
      ?₁ = 0.65 O
      X₂ = 0.55 O
      Xm = 44 O
      Rc = 440 O
      

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      V₁ = 440 / v2 Sin (314t-45°) Volts
      (i) Determine the ('I₁') primary current
      (ii) Determine the ('cose₁') primary power factor.
   3. (a) Discuss the following test for D.C. machines :
      (i) Hopkinson's and Swin burn's test
      

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      (ii) D. C. resistance test.
      (b) Discuss the following test on 1 phase transformers :
      (i) Sumpner's test
      (ii) Polarity test

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