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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER-VIII EXAMINATION WINTER 2017
Subject Code: X80901 Date:02/11/2017
Subject Name: Commissioning of Electrical Equipments
Time:02:30PM TO 5:00PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

What is earth resistance? Write methods to measure earth resistance and explain any one in detail.
07

Explain steps for commissioning of a power transformer.
07
Q.2

Discuss the properties of transformer oil. Explain dielectric test of transformer oil.
07

Explain different methods to measure slip of induction motor.
07
OR

Discuss the importance of neutral grounding. Discuss the comparison between different types of neutral grounding.
07
Q.3

What is the insulation resistance? Explain measurement method of insulation resistance using megger with diagram.
07

What is the significance of polarity in case of CT? How can we test the polarity of CT?
07
OR
Q.3

Explain the significance of Polarization Index Number.
07

What is drying out process for electrical machines? Why it is necessary? Explain any one method of drying out for rotating electrical machine.
07
Q.4

What are the causes of vibration and noise? How vibration and nose are measure in rotating electrical machines?
07

Explain Mechanical Endurance and impulse testing of circuit breakers.
07
OR
Q.4

How to carry out the bar to bar test on D.C. machines? Explain with circuit diagram.
07

Explain Murray Loop Test for fault detection in underground cable.
07
Q.5

What is the commissioning of electrical equipment? Which type's tests are performed on electrical equipments?
07

Explain the faults, causes and remedies of three phase induction motor.
07
OR
Q.5

Explain the tests performed for cable before commissioning of cable.
07

What is the significance of partial discharge measurement and tan delta test on case of transformer?
07