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Questions and Answers
What is the main advantage of AC motors over DC motors?
What is the main advantage of AC motors over DC motors?
- AC motors are more expensive
- AC motors require less maintenance (correct)
- AC motors are more efficient
- AC motors are more powerful
Which of the following is a characteristic of AC synchronous motors?
Which of the following is a characteristic of AC synchronous motors?
- They use brushes and commutators
- They are single-phase motors
- They have a variable speed
- They have a constant speed (correct)
What is the primary method used to control the speed of an AC motor?
What is the primary method used to control the speed of an AC motor?
- Using a variable resistance
- Changing the number of poles
- Varying the frequency (correct)
- Adjusting the voltage
Which of the following describes a method for producing a rotating magnetic field in an AC motor?
Which of the following describes a method for producing a rotating magnetic field in an AC motor?
What type of AC motor is well-suited for constant-speed applications?
What type of AC motor is well-suited for constant-speed applications?
Which characteristic of AC motors eliminates the problem of dangerous sparking?
Which characteristic of AC motors eliminates the problem of dangerous sparking?
What type of power systems are these motors designed for?
What type of power systems are these motors designed for?
Which type of AC motors are the most commonly used?
Which type of AC motors are the most commonly used?
How are the rotors of synchronous motors energized?
How are the rotors of synchronous motors energized?
What is the principle behind the operation of a three-phase induction motor?
What is the principle behind the operation of a three-phase induction motor?
How are the individual phase windings arranged in the stator of a three-phase induction motor?
How are the individual phase windings arranged in the stator of a three-phase induction motor?
Which rule is used to determine the electromagnetic polarity of the poles at any given instant in a three-phase induction motor?
Which rule is used to determine the electromagnetic polarity of the poles at any given instant in a three-phase induction motor?
In a three-phase system, the resultant magnetic field rotates in which direction?
In a three-phase system, the resultant magnetic field rotates in which direction?
At which point in the rotation cycle is the magnetic field in coils 1-1A at its maximum?
At which point in the rotation cycle is the magnetic field in coils 1-1A at its maximum?
What happens when the three-phase voltage completes one full cycle?
What happens when the three-phase voltage completes one full cycle?
At point 2, which winding experiences the maximum negative voltage?
At point 2, which winding experiences the maximum negative voltage?
What is the effect of the weaker magnetic fields in windings 1-1A and 2-2A at point 2?
What is the effect of the weaker magnetic fields in windings 1-1A and 2-2A at point 2?
What is the natural alignment of a bar magnet mounted in the center of the stator?
What is the natural alignment of a bar magnet mounted in the center of the stator?
What is the purpose of having no insulation between the core and the bars in a squirrel-cage rotor?
What is the purpose of having no insulation between the core and the bars in a squirrel-cage rotor?
What is the other type of rotor winding mentioned in the text?
What is the other type of rotor winding mentioned in the text?
What is the basic principle of operation for an induction motor, regardless of the rotor type?
What is the basic principle of operation for an induction motor, regardless of the rotor type?
What materials are typically used for the conducting bars in a squirrel-cage rotor?
What materials are typically used for the conducting bars in a squirrel-cage rotor?
How are the rotor bars connected in a squirrel-cage rotor?
How are the rotor bars connected in a squirrel-cage rotor?
What is the typical construction of a squirrel-cage rotor?
What is the typical construction of a squirrel-cage rotor?
What happens to the phase voltage when a motor is connected in delta configuration?
What happens to the phase voltage when a motor is connected in delta configuration?
How does the phase current change when a motor is connected in delta mode?
How does the phase current change when a motor is connected in delta mode?
What happens to the line current in a delta-connected motor compared to a star-connected motor?
What happens to the line current in a delta-connected motor compared to a star-connected motor?
What is the main difference in the stator field behavior between single-phase and polyphase induction motors?
What is the main difference in the stator field behavior between single-phase and polyphase induction motors?
How is voltage induced in the rotor of a single-phase induction motor?
How is voltage induced in the rotor of a single-phase induction motor?
What happens to the push-pull along the line if an outside force rotates the rotor of a single-phase motor?
What happens to the push-pull along the line if an outside force rotates the rotor of a single-phase motor?
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