GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-V (Old) EXAMINATION — WINTER 2019
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Subject Code: 150904 Date: 02/12/2019Subject Name: Elements Of Electrical Design
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1 (a) What are the functions and necessity of a starter for DC and AC motors. State different types of starters used in AC and DC motors. [07]
(b) What is armature winding? Define following terms for it: Turn, Coil, Coil side, Single Layer Winding, Double Layer winding [07]
Q.2 (a) Draw main circuit and control circuit of star delta starter for 3 phase squirrel cage induction motor. [07]
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(b) Prove that the section resistances of DC shunt motor starters are in geometrical progression. [07]OR
(b) Design a suitable 8 sections starter for a 20 hp, 250 V, 1000 rpm DC shunt motor from the following data:
Max. Torque= full load torque, Armature resistance= 0.4O, Efficiency=.85%. [07]
Q.3 (a) Explain the terms: Field Form Factor, Carter’s Coefficient, Staking Factor, Gap Contraction Factor. [07]
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(b) Explain various methods for calculating the mmf required for tapered teeth. [07]OR
Q.3 (a) Discuss step by step procedure to design horse shoe type electromagnet for a given supply voltage, required force and stroke. [07]
(b) Name various types of lifting electromagnets commonly used in practice and give comparison between them. [07]
Q.4 (a) Draw the winding diagram of a DC machine with 4 poles, 14 slots, progressive double layer lap winding. Show the position of brushes. [07]
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(b) Explain how the induced emf in stator winding of an AC machine is affected by Pitch Factor and Distribution Factor. [07]OR
Q.4 (a) Explain design procedure of small transformer in steps. [07]
(b) Prove that for a given variable choke coil, flux linkages remain constant with constant supply voltage and frequency. Also explain how variable inductance is obtained by varying air gap. State assumptions made if any. [07]
Q.5 (a) It is required to provide illumination of 120 lumens/m2 in a factory hall 30m*10m. Assume that the depreciation factor is 0.8, coefficient of utilization= 0.5, waste light factor=1.2 and efficacy of lamp is 15 lumens. Calculate number of lamps and their disposition. [07]
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(b) What do you mean by service connection. Give its types. Explain any two types. [07]OR
Q.5 (a) Which are types of wiring system? Explain any three of them. [07]
(b) Explain with neat sketch power and control circuit of Direct On line Starter. [07]
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This download link is referred from the post: GTU BE/B.Tech 2019 Winter Question Papers || Gujarat Technological University
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