Electric Traction (EEE) test-1

Which of the following is the most commonly used system of train electrification?

• 750 V DC

• 1500 V DC

• 25 kV AC

• 110 V DC

Answer explanation

The most commonly used system of train electrification is 25 kV AC. This system is preferred for its efficiency over long distances and is widely adopted in many countries for high-speed and heavy freight trains.

The system of train electrification that is used in high-speed trains in India is:

• 110 V DC

• 1500 V DC

• 25 kV AC

• 3 kV DC

Answer explanation

The correct answer is 25 kV AC, which is the standard electrification system for high-speed trains in India. This system allows for efficient power transmission over long distances, essential for high-speed rail operations.

In electric traction, the "schedule speed" of a train refers to:

• The maximum speed the train can achieve

• The average speed of the train including stops

• The speed at which the train is scheduled to travel

• The speed of the train when it reaches its destination

Answer explanation

The "schedule speed" of a train refers to the speed at which the train is scheduled to travel, taking into account the planned stops and travel times, making it distinct from maximum speed or average speed.

The tractive effort required by a train is the:

• Force needed to overcome the inertia of the train

• Force required to pull the train at a constant speed

• Force needed to accelerate the train and overcome friction and resistance

• Force used to decelerate the train

Answer explanation

The correct choice is the force needed to accelerate the train and overcome friction and resistance. Tractive effort encompasses both the acceleration of the train and the forces opposing its motion, such as friction.

The speed-time curve for a train typically consists of:

• Constant acceleration and deceleration phases only

• Acceleration, constant speed, and deceleration phases

• Constant speed only

• Only acceleration and no deceleration

Answer explanation

The speed-time curve for a train includes phases of acceleration, where the train speeds up, constant speed, where it travels at a steady pace, and deceleration, where it slows down. Thus, the correct choice is acceleration, constant speed, and deceleration phases.

The tractive effort for a train during acceleration depends on:

• The weight of the train and the frictional resistance

• The weight of the train and the wind resistance

• The maximum speed of the train

• The track type only

Answer explanation

The tractive effort during acceleration is influenced by the weight of the train, which affects the force needed to overcome frictional resistance. Wind resistance is less significant at lower speeds, making friction the key factor.

The specific energy consumption (SEC) in electric traction is defined as:

• Energy consumed per unit distance

• Energy consumed per unit mass of the train

• Energy consumed per unit time

• Energy consumed per unit of tractive effort

Answer explanation

The specific energy consumption (SEC) in electric traction refers to the energy consumed per unit distance traveled. This measure helps evaluate the efficiency of electric trains in terms of energy usage over distance.

In electric traction, the "schedule speed" is related to which of the following parameters?

• Distance traveled and total time taken

• Distance traveled and tractive effort

• Tractive effort and specific energy consumption

• Power rating of the locomotive

Answer explanation

The "schedule speed" in electric traction is defined as the distance traveled divided by the total time taken. This relationship highlights how speed is calculated based on distance and time, making this the correct choice.

Which of the following motors is most commonly used in electric traction?

• Induction motor

• Synchronous motor

• DC series motor

• Universal motor

Answer explanation

The DC series motor is preferred in electric traction due to its high starting torque and ability to handle variable loads, making it ideal for applications like trains and trams.

The power output of a traction motor is primarily used to:

• Operate the locomotive lights

• Provide tractive effort to move the train

• Operate the train’s air-conditioning systems

• Power auxiliary equipment only

Answer explanation

The power output of a traction motor is primarily used to provide tractive effort to move the train, enabling it to accelerate and maintain speed, rather than powering auxiliary systems or lights.