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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-II EXAMINATION WINTER 2018
Subject Code:X21901 Date: 05/01/2019
Subject Name: Electrical Machines Electronics
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt any five questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Explain construction features and working principle of DC motor.
07

Explain construction and working principle of 1-phase transformer.
07
Q.2

Explain the types of DC motors with diagram.
07

Explain construction and working principle of 3-phase induction motor.
07
Q.3

Explain methods of speed control of DC shunt and series motors.
07

What is auto transformer? Discuss the advantages, disadvantages and applications of auto transformer.
07
Q.4

What are the conditions for parallel operation of alternators? Explain synchronizing of alternators.
07

Explain comparison of over head and underground distribution system.
07
Q.5

What is tariff? Explain types of tariff.
07

What is a power factor? Discuss the causes of low power factor. Also write the disadvantages of low power factor.
07
Q.6

What is substation? List out the equipments which are used in substation with their function.
07

Explain half wave and full wave rectifier circuit with diagram.
07
Q.7

Explain De-Morgan's theorems.
07

Explain any four logic gates with their truth table.
07