BEEE-UNIT-II ELECTRICAL MACHINES

What is the main difference between DC and AC machines?

• Color of the machines

• Type of current used

• Size of the machines

• Number of machines used

Explain the working principle of a transformer.

• A transformer operates based on the principle of electromagnetic induction.

• A transformer functions by utilizing chemical reactions.

• A transformer works by converting sound waves into electrical energy.

• A transformer operates based on the principle of gravitational force.

What is the function of a commutator in a DC machine?

• To cool down the motor

• To reverse the direction of current flow in the armature windings

• To regulate the voltage output

• To increase the speed of the machine

Define slip in the context of an induction motor.

• Slip is the difference between synchronous speed and rotor speed in an induction motor.

• Slip is the ratio of stator current to rotor current in an induction motor.

• Slip is the speed at which the motor operates when it is not powered.

• Slip is the term used to describe the efficiency of an induction motor.

How does a synchronous motor differ from an induction motor?

• Synchronous motor has a higher efficiency than an induction motor.

• Synchronous motor does not require any power source, while an induction motor does.

• Synchronous motor is used for low power applications, while an induction motor is used for high power applications.

• Synchronous motor requires a separate DC power source for the rotor, while an induction motor does not.

What are the different types of AC machines?

• Synchronous machines and asynchronous machines

• Induction machines and commutator machines

• Direct current machines and alternating current machines

• Single-phase machines and three-phase machines

Why are transformers used in electrical systems?

• Transformers are used to step up or step down voltage levels in electrical systems.

• Transformers are used to cook food in electrical systems.

• Transformers are used to play music in electrical systems.

• Transformers are used to control the weather in electrical systems.

What is the role of the stator in an AC machine?

• Regulates the voltage output

• Converts electrical energy into mechanical energy

• Generates a rotating magnetic field

• Controls the speed of the rotor

Explain the concept of back EMF in a DC motor.

• Back EMF in a DC motor is the voltage induced in the motor's windings due to the motor's rotation, which opposes the applied voltage and regulates the motor's speed.

• Back EMF is the resistance encountered by a DC motor

• Back EMF increases the speed of a DC motor

• Back EMF is the current flowing in the opposite direction in a DC motor

What is the significance of the rotor in an induction motor?

• The rotor determines the speed of the induction motor.

• The rotor is responsible for generating electricity in the induction motor.

• The rotor is essential for converting electrical energy into mechanical energy in an induction motor.

• The rotor is used for cooling the induction motor.