21. Which of the following statements is true?
- A Composite system consists of a combination of diesel engine and DC series motor
- A composite system consists of a combination of diesel engine and AC single-phase motor
- In a composite system-phase power received is converted into DC or three-phase power AC system
- A composite system consists of the use of a combination of DC and AC motors on the same locomotive
22. In addition to the actual running time between stops, the speed of the train that is estimated taking into account the time of stop at a station, is known as
- Average speed
- Scheduled speed
- Notching speed
- Free running speed
23. Why is the energy consumption in propelling the train required for?
- Work against gravity while moving up the gradient
- Work against the resistance to motion
- Only i
- i and ii
- i, ii and iii
- i and iii
24. Which of the following indicates the usual specific energy consumption for suburban train service?
- 18 to 25 watt-hours per tonne km
- 50 to 75 watt-hours per tonne km
- 125 to 150 watt-hours per tonne km
- 155 to 200 watt-hours per tonne km
25. Which of the following is true about coefficient of adhesion?
- It is same on a.c. and d.c. traction systems.
- It is high in case of d.c. traction and low in a.c. traction
- It is low in case of d.c. traction and high in a.c. traction
- None of these
26. The weight of a locomotive is 120 tonnes. If the axle load is not to exceed 20 tonnes, the number of axles required is
27. Free running and Coasting periods are generally long in case of
- Urban service
- Sub-urban service
- Main-line service
- All options are corrects
28. In suburban services as compared with urban service
- the coasting period is longer
- the coasting period and free-running periods are the same
- the coasting period is smaller but the free-running period is longer
- the coasting period is smaller