Question 1 1. A transformer has a A connected primary and a star connected secondary, working on 50 Hz supply. The line voltages on primary and secondary sides are 6.6 KV and 400 V respectively. The line current on the primary side is 8 A and the secondary side has a balanced load of 0.6 p.f. lagging. Find (a) output of the transformer (b) the line current on the secondary side. (Ans. (a) 54.857 kW (b) 132 A) 2. A scott connected transformer set supplies two electric furnaces at 110 V each from a 3 phase, 4400 V system. If the furnace connected to teaser transformer secondary takes 270 kW and other one connected to main transformer secondary takes 450 kW at unity p.f.. find the line currents taken from the three phases mains. (Ans.: 108.2486 A, 108.2486 A, 70.9364 A) 3. Explain the choice of connection of 3 phase transformers. 4. What are instrument transformers? State its advantages and disadvantages. 5. Explain the working of current transformer. 6. Explain the construction and working of potential transformer. 7. Compare C.T. and P.T.

Question 1 1. A transformer has a A connected primary and a star connected secondary, working on 50 Hz supply. The line voltages on primary and secondary sides are 6.6 KV and 400 V respectively. The line current on the primary side is 8 A and the secondary side has a balanced load of 0.6 p.f. lagging. Find (a) output of the transformer (b) the line current on the secondary side. (Ans. (a) 54.857 kW (b) 132 A) 2. A scott connected transformer set supplies two electric furnaces at 110 V each from a 3 phase, 4400 V system. If the furnace connected to teaser transformer secondary takes 270 kW and other one connected to main transformer secondary takes 450 kW at unity p.f.. find the line currents taken from the three phases mains. (Ans.: 108.2486 A, 108.2486 A, 70.9364 A) 3. Explain the choice of connection of 3 phase transformers. 4. What are instrument transformers? State its advantages and disadvantages. 5. Explain the working of current transformer. 6. Explain the construction and working of potential transformer. 7. Compare C.T. and P.T.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.28MCQ

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Question 1
1. A transformer has a A connected primary and a star
connected secondary, working on 50 Hz supply. The
line voltages on primary and secondary sides are 6.6
KV and 400 V respectively. The line current on the
primary side is 8 A and the secondary side has a
balanced load of 0.6 p.f. lagging. Find (a) output of the
transformer (b) the line current on the secondary side.
(Ans. (a) 54.857 kW (b) 132 A)
2. A scott connected transformer set supplies two
electric furnaces at 110 V each from a 3 phase, 4400 V
system. If the furnace connected to teaser transformer
secondary takes 270 kW and other one connected to
main transformer secondary takes 450 kW at unity p.f..
find the line currents taken from the three phases
mains. (Ans.: 108.2486 A, 108.2486 A, 70.9364 A)
3. Explain the choice of connection of 3 phase
transformers.
4. What are instrument transformers? State its
advantages and disadvantages.
5. Explain the working of current transformer.
6. Explain the construction and working of potential
transformer.
7. Compare C.T. and P.T.

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