Traction Systems Interview Questions and Answers:

1. Why steam engine drive is not suitable for urban and suburban services where distance between stations is small ?

Ans. Because of low coefficient of adhesion it is not possible to have acceleration and retardation with steam engine drive as high as with electric drive. Steam engine drive is, therefore, not suitable for urban or suburban services where distance between stations is small.

2. Why steam engine drive is not suitable for underground railway?

Ans. Owing to smoke, steam engine drive cannot be employed for underground railways.

3. How is speed controlled in direct IC engine drive ?

Ans. By using a gearbox.

4. What is the operational efficiency of IC engine electric drive ?

Ans. About 25 per cent.

5. What are the limitations of battery electric drive ?

Ans. The major limitations of the battery electric drive are the small capacity of the batteries and the necessity for frequent charging and limited speed range.

6. What is the major drawback of electric traction ?

Ans. The greatest drawback of electric traction is that it involves a heavy initial expenditure for the power supply system and, in the case of tramways, for the track rails and electrical return system, in addition to the cost of vehicles, depots etc.

7. What are the major disadvantages of the tramway ?

Ans. The great disadvantage of tramway is that it needs laying of overhead supply system and track for its use which is costly to maintain and constitutes a source of danger to other road users. The other main drawback of tramway is lack of manoeuvrability in congested areas and noise.

8. Why electric traction system is considered superior over other systems of traction in India, even when there is a power crisis in India.

Ans. In our country electric energy is available at cheaper rates comparatively because of availability of substantial sources of hydropower generation and nuclear power generation. By electrification of railways high grade coal, which is limited in quantity in our country, will be saved which can be used for some other useful purposes.

9. Which of the system (dc or ac) is preferred for suburban services and road transport where stops are frequent and distances of run are small ?

Ans. DC system.

10. What is the value of voltage used in overhead supply for trains in India ?

Ans. 25 kV.

11. Why single phase system is preferred for main line railway service ?

Ans. AC single phase system is invariably adopted for main line service where the cost of overhead structure is of more importance and rapid acceleration and retardation is not so important as for suburban railways.

12. What are the most important requirements of the main line railway service ?

Ans. High maximum (crest) speed and minimum cost of overhead structure.

13. Which of the system is preferred for main line railway service ?

Ans. Single phase ac system.

14. What are the most important requirements of suburban line railway service ?

Ans. Rapid acceleration and retardation, no interference to nearby communication lines and operation of motors free from adverse effects of voltage fluctuations.

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