DBATU Model MCQ - Electrical Machines 2

Welcome to your Electrical Machine 2, dated April 20, 2021

A differential relay comparator used for the protection of three phase transformers has

One comparator

Two comparator

Three comparator

Six comparator

2. In double delta transformation, a double delta refers to the case where there are two delta transformations inDeselect Answer

Parallel

Series

Both series and parallel

Neither series nor parallel

3. In Scott connection, the voltage across the teaser leads the mains byDeselect Answer

30 degree

90 degree

60 degree

1200 degree

4. For large low voltage transformers, the most commonly used connections areDeselect Answer

Star - star connection

Delta - delta connection

V connection

All of these

5. In a three phase transformer, the current flowing in three primaries produces three corresponding fluxes. The sum of these three fluxes at any instant isDeselect Answer

Zero

Three times of any individual flux

One third of any individual flux

None of these

6. The constant current transformer are mainly used forDeselect Answer

Supplying series connected street light

Personal computers

Arc welding

Electric toys

7. Small iron core transformers used in certain frequency range is also called audio frequency transformer. The audio frequency range isDeselect Answer

20 to 2000 Hz

20 to 20000 Hz

2 to 2000 Hz

200 to 20000 Hz

8. The output voltage of constant voltage transformer contains excessive harmonics which can be filtered out by usingDeselect Answer

RC filter

RL filter

LC filter

None of these

9. A constant voltage transformer is fed with the sinusoidal input voltage. Its output isDeselect Answer

Sinusoidal

Flat topped