Electrical Machines Test Questions Start Creating PDF

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

1. One comparator
2. Two comparator
3. Three comparator
4. Six comparator

MCQ: In double delta transformation, a double delta refers to the case where there are two delta transformations in

1. Parallel
2. Series
3. Both series and parallel
4. Neither series nor parallel

MCQ: Most familiar application of zig - zag transformer is as

1. Ground reference on an ungrounded system
2. Converting single phase to two phase
3. Reducing harmonics
4. All of these

MCQ: In a single phase, full wave bridge circuit and in three phase, delta full wave bridge circuit, the ripple voltage frequency is always

1. Twice the line frequency, six times the line frequency
2. Both will be twice the line frequency
3. Both will be six times the lines frequency
4. None of these

MCQ: In Scott connection, the voltage across the teaser leads the mains by

1. 30 degree
2. 60 degree
3. 90 degree
4. 120 degree

MCQ: Scott connection is used for the conversion of

1. Single phase to three phase
2. Three phase to single phase
3. Single phase to two phase
4. All of these

MCQ: In T-T connection, the ratio of actual capacity to the available capacity is

1. 1
2. 0.928
3. 1.928
4. 0.5

MCQ: In T-T connection, the percentage tapping of main transformer and teaser transformer are

1. 50%, 86.6%
2. 50%, 50%
3. 86.6%, 86.6%
4. 86.6%, 50%

MCQ: With a bank of two single phase transformers connected in V - V fashion supplying a balanced three phase load with Cosφ as power factor. The power factor of the two transformers is given by

1. Cosφ , Cosφ
2. Cosφ, Cos(30+φ)
3. Cos(30-φ), Cos(30+φ)
4. Cos(30-φ), Cosφ

MCQ: The average power factor at which V-V bank is operating is less than that with the load. The power factor is

1. 57.7% of the balanced load power factor
2. 66.7% of the balanced load power factor
3. 86.6% of the balanced load power factor
4. None of theses