Tuesday, 11 June 2019

MOST IMP QUESTIONS FOR DC MACHINE

Dear Friends,

Here I attach the MOST IMP Questions for DCMT (DC Machine) subject.

Practice Paper prepared by Aakash Sir.


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ET ROLL NO :____________                                      GTU Enrollment no:________________
ELECTRO TUTOR, RAOPURA
PRE GTU EXAM
DIPLOMA ENGINEERING – SEMESTER – III • OCTOBER EXAM 2018
Subject Code: 3330902                                                                              Date: 04-10-2018
Subject Name: DC MACHINES AND TRANSFORMER
Time:    5.00 PM to 7.30 PM                                                                         Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicates the full marks.
4. Each question carries equal marks (14 marks)
Q.1 Answer any seven out of ten. 14
1 Define (1) Pole Pitch (2) Back Pitch
2 List the different types of losses occurring in DC motor.
3 State the application of Auto transformer.
4 The necessity of commutator in d.c. generator.
5 Classify the different types of d.c. generator
6 What is Armature reaction in d.c. generator?
7 Write the basic principle of d.c. motor.
8 List the speed control of d.c. shunt motor and d.c. series motor.
9 Explain the power stages and various losses occurring in D.C. motor.
10 Explain the need for parallel operation.
Q.2 (a) Derive the emf equation for single phase transformer. 4
OR
(a) Write the equation of torque for DC motor and factors affecting the value of torque for DC motor.
(b) Explain different losses occurring in the transformer. 3
OR
(b) Explain the principle of motor action.
(c) Write the application of D.C. motor. 3
OR
(c) State advantages and disadvantages of Autotransformer
(d) Explain the construction of welding transformer. 4
OR
(d) Draw & explain Speed-current and Speed torque characteristics of a DC Shunt motor.
Q.3 (a) Explain Swinburn’s Test of D.C. machine. 3
OR
(a) Explain the direct loading test of the transformer.
(b) Explain the O.C & S.C. test to find out the efficiency of the transformer. 4
OR
(b) Explain the brake test to find the efficiency for D.C. motor.
(c) Explain different types of D.C. generators with circuit diagram. 3
OR
(c) Explain the difference between the three point starter and four-point starter.
(d) Draw and explain speed and armature current characteristics of DC series motor. 4
Q.4 (a) Draw and explain the working of three-point DC shunt motor starter and four-point starter. 7
(b) Explain the starting and running characteristics of the D.C. motor. 7
Q.5 (a) Explain the construction of D.C. machine with neat sketch and function of each part. 7
(b) Explain necessity and required conditions for parallel operation of two 1- phase transformers. 7
********BEST OF LUCK!!!!!!!********




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