Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 5th Sem Old 150904 Elements Of Electrical Design Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (Old) EXAMINATION ? WINTER 2019
Subject Code: 150904 Date: 02/12/2019
Subject Name: Elements Of Electrical Design
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
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
(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= 0.4 ?, Efficiency=.85%,.
07
Q.3 (a) Explain the terms: Field Form Factor, Carter?s Coefficient, Staking Factor, Gap
Contraction Factor.
07
(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
(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/m
2
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
(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 post was last modified on 20 February 2020