Download GTU B.Tech 2020 Summer 8th Sem 2180901 Testing And Commissionong Of Electrical Equipment Question Paper

Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Summer 8th Sem 2180901 Testing And Commissionong Of Electrical Equipment Previous Question Paper

Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
B.E SEMESTER?VIII EXAMINATION ?SUMMER 2020
Subject Code: 2180901




Date: 26/10/2020
Subject Name: TESTING AND COMMISSIONONG OF ELECTRICAL EQUIPMENT
Time:02.30 PM TO 05.00 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 do you mean by polarization index with reference to small size machine
03
and large size machine?

(b) What is the importance of insulation resistance for electrical equipment? What
04
is the reason for deterioration of insulation resistance?

(c) Which are different test performed on electrical equipment from
07
manufacturing process to commissioning process? What is their significance?
Q.2
(a) Give the connection difference between Dy1 and Dy11 for transformer.
03

(b) Explain how the H.V bushing and L.V. Bushing installed in transformer.
04
Explain type of bushing.

(c) What are the characteristics of transformer oil? How can we improve it?
07


OR


(c) What are needs for drying out of transformer? Explain hot oil circulation
07
method for drying out.
Q.3
(a) What are the possible reasons for vibration in D.C.Machine? Give their
03
remedies.

(b) Where the insulation resistance of transformer is to be measured? Why is
04
resistances decrease after some time?

(c) How the switching impulse test performed on transformer? Give the
07
characteristics of switching impulse.


OR

Q.3
(a) What is importance of polarity test in power transformer and current
03
transformer?

(b) Why we are measuring R15 and R60 reading while measuring PI index?
04

(c) Give the reason, why should we kept the tapping on LV side not on HV side
07
in some special case of transformer ?
Q.4
(a) What are reasons for vibration in induction motor?
03

(b) What are the reasons for temperature rise in motor while carrying a rated load?
04

(c) How can we find short circuit winding or short circuit bar in rotating machine?
07

OR

Q.4
(a) What are the conditions for parallel connection of transformer?
03

(b) Can we connect DY1 AND DY11 transformer in parallel? Justify your answer.
04

(c) Draw the vector diagram and connection diagram for YY0 and DDO.
07
Q.5
(a) What are the possible reasons if circuit breaker is not TURN ON if we give
03
ON command?

(b) How the contact resistance can be measured in circuit breaker?
04

(c) What are the different test performed on out-door circuit breaker?
07


OR
Q.5
(a) What are the methods to measure earthling resistance in sub-station?
03
(b) Draw YZ0 and YZ1 connection for three phase transformer.
04
(c) Which are the different tests performed for commissioning of transformer?
07
Explain any two with its significance.
1

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