Understanding Electrical Machines

What is the principle of operation of AC machines?

• AC machines use chemical reactions for energy conversion.

• The principle of operation of AC machines is based on electromagnetic induction.

• AC machines function solely on mechanical principles.

• AC machines operate on thermal conduction.

Name two types of AC machines.

• Stepper Motor

• Brushless Motor

• AC Induction Motor, Synchronous Motor

• DC Motor

What is the main difference between synchronous and asynchronous machines?

• Synchronous machines require a battery to operate; asynchronous machines do not.

• Synchronous machines can operate at varying speeds; asynchronous machines cannot.

• Asynchronous machines are more efficient than synchronous machines at all loads.

• Synchronous machines run at a constant speed synchronized with supply frequency; asynchronous machines do not.

Explain the function of a rotor in an AC machine.

• The rotor converts electrical energy into mechanical energy in an AC machine.

• The rotor stores mechanical energy in an AC machine.

• The rotor generates electrical energy in an AC machine.

• The rotor regulates the temperature in an AC machine.

What are the advantages of using DC machines?

• Advantages of using DC machines include ease of speed control, simple construction, high starting torque, efficiency in low-speed applications, and easy maintenance.

• Low starting torque

• Complex construction

• High efficiency at high speeds

Describe the construction of a DC motor.

• A DC motor consists of a flywheel, gears, and a capacitor.

• A DC motor is constructed with a stator, rotor, commutator, brushes, and a power supply.

• A DC motor is made up of a transformer, inductor, and diode.

• A DC motor includes a housing, fan, and heat sink.

What is back EMF in a DC motor?

• Back EMF is the voltage generated by a DC motor that opposes the applied voltage.

• Back EMF is the resistance of the motor windings.

• Back EMF is the power consumed by the motor.

• Back EMF is the current flowing through a DC motor.

How does a transformer work?

• A transformer transfers electrical energy between two or more circuits through electromagnetic induction.

• A transformer generates electricity from solar energy.

• A transformer stores electrical energy in batteries.

• A transformer converts AC to DC power.

What is the purpose of a transformer in electrical systems?

• To increase current levels in electrical systems.

• To change voltage levels in electrical systems.

• To convert AC to DC power.

• To store electrical energy for later use.

Define the turns ratio in a transformer.

• The turns ratio is the ratio of voltage to current in a transformer.

• The turns ratio is the ratio of the transformer’s efficiency to its power output.

• The turns ratio is the ratio of primary turns to secondary turns in a transformer.

• The turns ratio is the total number of turns in a transformer.