Three-Phase Systems in Power Applications problems
- 1. In a Y-connected source feeding a △-connected load,
Options- A. each phase of the load has one-third of the full line voltage across it
- B. each phase of the load has two-thirds of the full line voltage across it
- C. each phase of the load has the full line voltage across it
- D. each phase of the load has a voltage across it equal to
Discuss
Correct Answer: each phase of the load has the full line voltage across it
- 2. The stator is the rotating assembly in a generator or motor.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
The two main parts of a generator or motor can be described in either mechanical or electrical terms:
Mechanical:
Rotor: The rotating part of an electrical machine
Stator: The stationary part of an electrical machine
Electrical:
Armature: The power-producing component of an electrical machine. In a generator, alternator, or dynamo the armature windings generate the electric current. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an electrical machine. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator.
Mechanical:
Rotor: The rotating part of an electrical machine
Stator: The stationary part of an electrical machine
Electrical:
Armature: The power-producing component of an electrical machine. In a generator, alternator, or dynamo the armature windings generate the electric current. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an electrical machine. The magnetic field of the dynamo or alternator can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator.
- 3. Power is measured in a three-phase load by using an ammeter.
Options- A. True
- B. False Discuss
Correct Answer: False
- 4. A simple three-phase generator consists of three conductive loops separated by 120°.
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. A simple two-phase generator consists of two conductive loops separated by 90°, rotating in a magnetic field.
Options- A. True
- B. False Discuss
Correct Answer: True
- 6. Polyphase is characterized by two or more sinusoidal voltages, each having a different phase angle.
Options- A. True
- B. False Discuss
Correct Answer: True
- 7. In a Y-connected generator, there is a 120° difference between each line voltage and the nearest phase voltage.
Options- A. True
- B. False Discuss
Correct Answer: False
- 8. The term squirrel-cage applies to a type of three-phase ac generator.
Options- A. True
- B. False Discuss
Correct Answer: True
- 9. An alternator is an electromechanical ac generator.
Options- A. True
- B. False Discuss
Correct Answer: False
- 10. In a △-connected generator, there is a 120° difference between each line current and the nearest phase current.
Options- A. True
- B. False Discuss
Correct Answer: False
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