Which of the following factors causes temperature rise in electric drives?

• Frictional losses

• Copper and iron losses

• Ambient temperature

• All of the above

Answer explanation

Temperature rise in electric drives is caused by frictional losses, copper and iron losses, and ambient temperature. Therefore, the correct answer is 'All of the above' as all these factors contribute to increased temperatures.

Which load type is characterized by constant power demand over a long period?

• Intermittent load

• Continuous load

• Variable load

• Peak load

Answer explanation

A continuous load is defined by a constant power demand over an extended period, unlike intermittent or variable loads that fluctuate. Therefore, the correct answer is continuous load.

What is load equalization?

• Reducing the weight of the load

• Making the load variable

• Smoothing out fluctuating loads over time

• Increasing the motor rating

Answer explanation

Load equalization refers to smoothing out fluctuating loads over time, ensuring a more consistent and manageable load on systems, which helps in maintaining efficiency and stability.

Which of the following is an intermittent load example?

• Pump

• Elevator

• Fan

• Furnace

Answer explanation

An elevator is an intermittent load because it operates in cycles, moving between floors, unlike a pump, fan, or furnace, which typically run continuously during operation.

Variable load drives are used in:

• Textile machinery

• Electric fans

• Grinding machines

• Welding transformers

Answer explanation

Variable load drives are essential in textile machinery as they allow for precise control of speed and torque, accommodating the varying demands of different textile processes, making this the correct choice.

What is electric traction?

• Use of steam for traction

• Use of internal combustion engines

• Use of electric power for traction

• Use of solar power

Answer explanation

Electric traction refers to the use of electric power to drive vehicles, particularly trains and trams. This method is efficient and environmentally friendly compared to steam or internal combustion engines.

Which of the following is NOT a system of track electrification?

• DC system

• AC single-phase system

• Three-phase AC system

• Solar-powered track system

Answer explanation

The Solar-powered track system is NOT a traditional system of track electrification like DC, AC single-phase, or three-phase AC systems, which use electrical power from external sources.

Which of the following voltages is used in DC electric traction systems in India?

• 750 V

• 1500 V

• 25 kV

• 230 V

Answer explanation

In India, DC electric traction systems primarily use 1500 V for efficient train operation. This voltage is standard for many railways, ensuring optimal performance and compatibility with existing infrastructure.

The special feature of traction motors is:

• High starting torque

• Low inertia

• Constant speed

• High efficiency only at full load

Answer explanation

Traction motors are designed to provide high starting torque, which is essential for moving heavy loads from a standstill. This feature allows them to accelerate quickly, making them ideal for applications like trains and electric vehicles.

Which of the following is a mechanism of train movement?

• Constant pressure operation

• Speed-time curve analysis

• Load curve

• Voltage drop

Answer explanation

Speed-time curve analysis is a key mechanism for understanding train movement, as it illustrates the relationship between speed and time, helping to optimize performance and efficiency during operation.