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Electrical Engineering Objective Questions { Utilisation of Electrical Energy }

1. The most vital factor against electric traction is the
A. necessity of providing a negative booster
B. possibility of electric supply failure
C. high cost of its maintenance
D. high initial cost of laying out over-head electric supply system.

2. For the single-phase ac system of track electrification, low frequency is desirable because of the following advantage/s
A. it improves commutation properties of ac motors
B. it increases ac motor efficiency
C. it increases ac motor power factor
D. all of the above

3. The main reason for choosing the composite 1-phase ac to dc system for all future track electrification in India is that it
A. needs less number of sub-stations
B. combines the advantages of high voltage ac distribution at 50 Hz with dc series traction motors
C. provides flexibility in the location of sub-stations
D. requires light overhead catenary

4. The free-running speed of a train does NOT depend on the
A. duration of stops
B. distance between stops
C. running time
D. acceleration

5. Tractive effort of an electric locomotive can be increased by
A. increasing the supply voltage
B. using high kW motors increasing dead weight over the driving axles
C. both and
D. both and

6. Welding is not done directly from the supply mains because
A. it is customary to use welding machines
B. its voltage is too high
C. its voltage keeps fluctusting
D. it is impracticable to draw heavy currents

7. In electric welding, arc blow can be avoided by
A. using bare electrodes
B. welding away from earth ground connection
C. using ac welding machines
D. increasing arc length

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