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Download PTU B.Tech 2021 Jan EE 5th Sem 70554 Synchronous Machines Question Paper

Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January EE 5th Sem 70554 Synchronous Machines Previous Question Paper

This post was last modified on 26 June 2021

This download link is referred from the post: PTU B.Tech 5th Semester Last 10 Years 2011-2021 Previous Question Papers|| Punjab Technical University


Roll No. ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ ‘ Total No. of Pages : 02

Total No. of Questions : 18

B.Tech. (EE) PT (2012 Onwards) (Sem.=5)

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SYNCHRONOUS MACHINES

Subject Code : BTEE-501

M.Code : 70554

Time : 3 Hrs. Max. Marks : 60

INSTRUCTION TO CANDIDATES :

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  1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
  2. SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
  3. SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.

SECTION-A

Answer briefly :

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  1. Differentiate salient pole and cylindrical rotor synchronous generators.
  2. Why fractional pitch winding is preferred over full-pitch winding?
  3. Explain the role of damper windings in synchronous generator.
  4. Explain armature reaction of a synchronous machine.
  5. Why is the short circuit characteristics of an alternator is linear?
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  7. Why are synchronous motors not self-starting?
  8. What is the effect of increase in excitation of a synchronous motor?
  9. How hunting can be reduced in alternators?
  10. Why are alternators operated in parallel?
  11. Explain infinite bus-bars.
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SECTION-B

  1. Derive the expression for (i) pitch factor and (ii) distribution factor.
  2. Draw and explain the phasor diagram of a loaded alternator for loads at lagging power factor.
  3. Explain the Poteir triangle method of finding regulation of an alternator.
  4. Draw and explain the equivalent circuit of a synchronous motor.
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  6. Derive the condition for maximum power output of a synchronous generator connected to infinite bus-bar and operating at constant excitation.

SECTION-C

  1. Calculate the rms value of the induced emf per phase of a 10-pole, 3-phase, 50 Hz alternator with 2 slots per pole per phase and 4 conductors per slot in two layers. The coil span is 150°. The flux per pole has a fundamental component of 0.12 Wb and 15% third harmonic component.
  2. A 3-phase, star-connected, 1000 kVA, 11 kV alternator has rated current of 52.5 A. The ac resistance of the winding per phase is 0.45 Q. The test results are given below:
    OC Test: Field current = 12.5 A, Voltage between lines = 422 V

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    SC Test: Field current = 12.5 A, Line current = 52.5 A
    Determine the full load voltage regulation-of the alternator (i) 0.8 pflagging and (ii) 0.8 pf leading.
  3. A 3-phase, 415 V, 6-pole, 50 Hz star-connected synchronous motor has emf of 520 V (L-L). The stator winding reactance of 2 Q per phase, and the motor develops a torque of 220 Nm. The motor is operating at 415 V, 50 Hz bus.
    1. Calculate the current drawn from the supply and its power factor.
    2. Draw the phasor-diagram showing all the relevant quantities.
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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.

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This download link is referred from the post: PTU B.Tech 5th Semester Last 10 Years 2011-2021 Previous Question Papers|| Punjab Technical University