--- Content provided by FirstRanker.com ---
Subject Code: 2150904
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-V (NEW) EXAMINATION - SUMMER 2019
--- Content provided by FirstRanker.com ---
Subject Name: Elements of Electrical Design
Time: 02:30 PM TO 05:00 PM
--- Content provided by FirstRanker.com ---
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
--- Content provided by FirstRanker.com ---
Q.1
--- Content provided by FirstRanker.com ---
(a) Define: (1) Field form factor (2) Gap contraction factor for slots. [03]
(b) How Magnetizing current is calculated for 3 phase induction motor? [04]
--- Content provided by FirstRanker.com ---
(c) Explain different types of wiring used in Electrical installation? [07]
Q.2
(a) Define Real and apparent flux density and write the equation for relation between them. [03]
--- Content provided by FirstRanker.com ---
(b) What is carter’s fringing curves? Why it is used? [04]
(c) A 15 kW 230 volt, 4 pole d.c. machine has the following data: armature diameter= 0.25m; armature core length=0.125m, length of air gap at pole centre= 2.5mm, flux per pole = 11.7 mWb, ratio Pole arc/pole pitch = 0.66. Calculate the mmf required for the air gap (i) if the armature surface is treated as smooth ii) if the armature is slotted and gap contraction factor is 1.18. [07]
OR
--- Content provided by FirstRanker.com ---
(c) Calculate the mmf required for the air gap of a machine having core length=0.32m, including 4 ducts of 10mm each , pole arc =0.19m, slot pitch = 65.4 mm , slot opening = Smm, air gap length = 5 mm, flux per pole = 52 mWb. Given Carter’s.coefficient is 0.18 for slot opening/gap length =1, and is 0.28 for duct,width/ gap length = 2. [07]
Q.3
(a) Classify the various types of a.c. armature windings. [03]
--- Content provided by FirstRanker.com ---
(b) What is the function of field regulator in case of d.c. shunt motor? Explain briefly. [04]
(c) Design a suitable 5 section starter for a 7.5 kW, 250 V, 1000 rpm DC shunt motor from the following data: Maximum starting torque = 1.5 times the full load torque, Armature circuit resistance = 0.5 Q, Full load efficiency = 85% [07]
--- Content provided by FirstRanker.com ---
OR
(a) Explain in brief the progressive and retrogressive lap windings. [03]
(b) What is the function of field regulator in case of d.c. shunt generator? Explain briefly. [04]
--- Content provided by FirstRanker.com ---
(c) Find the resistance of each section of a rotor resistance starter of a slip-ring induction motor having a rotor resistance of 0.02 Q per phase and a full load slip of 3%. Use 9 studs. Assume maximum starting current = Full load current. Also determine the slip at various studs. [07]
Q.4
(a) What is armature winding? Define following term with respect to it (1) Turn (2) Coil (3) Coil side [03]
--- Content provided by FirstRanker.com ---
(b) Define : (1) Coil pitch (2) Commutator pitch (3) Back pitch (4) Front pitch [04]
(c) Find and give comments whether the following wave windings are symmetrical or not: (i) 4-pole, 25-slots, 2 coil sides per slot (1) 4-pole, 14-slots, 2 coil sides per slot [07]
--- Content provided by FirstRanker.com ---
OR
(a) Differentiate between integral and fractional slot windings also state advantages of fractional slot windings. [03]
(b) What do you mean by “dummy coil”? What is its application? Also explain the use of equalizer connections in d.c. armature winding. [04]
--- Content provided by FirstRanker.com ---
(c) Workout an arrangement for equalizer connection for 16 slots, 4 pole, 16 coils simplex lap wound d.c. machine. Use 4 equalizer rings. [07]
Q.5
(a) State the condition for designing a single layer mush winding. [03]
--- Content provided by FirstRanker.com ---
(b) Explain the importance of current carrying capacity and voltage drop while determine the size of conductor. [04]
(c) Discuss the design procedure of single phase variable choke coil. [07]
--- Content provided by FirstRanker.com ---
OR
(a) What is the purpose of estimating and costing? [03]
(b) What are the factors that should be considered while selecting the type of wiring system? [04]
--- Content provided by FirstRanker.com ---
(c) Define wiring diagram, schematic diagram and single line diagram. Explain using suitable example. [07]
Date: 17/06/2019
Total Marks: 70
--- Content provided by FirstRanker.com ---
This download link is referred from the post: GTU BE 2019 Summer Question Papers || Gujarat Technological University
--- Content provided by FirstRanker.com ---