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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- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- 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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- Differentiate salient pole and cylindrical rotor synchronous generators.
- Why fractional pitch winding is preferred over full-pitch winding?
- Explain the role of damper windings in synchronous generator.
- Explain armature reaction of a synchronous machine.
- Why is the short circuit characteristics of an alternator is linear?
- Why are synchronous motors not self-starting?
- What is the effect of increase in excitation of a synchronous motor?
- How hunting can be reduced in alternators?
- Why are alternators operated in parallel?
- Explain infinite bus-bars.
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SECTION-B
- Derive the expression for (i) pitch factor and (ii) distribution factor.
- Draw and explain the phasor diagram of a loaded alternator for loads at lagging power factor.
- Explain the Poteir triangle method of finding regulation of an alternator.
- Draw and explain the equivalent circuit of a synchronous motor.
- Derive the condition for maximum power output of a synchronous generator connected to infinite bus-bar and operating at constant excitation.
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SECTION-C
- 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.
- 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--- Content provided by FirstRanker.com ---
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. - 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.
- Calculate the current drawn from the supply and its power factor.
- 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