Title: AC Motors Test
Course: Basic of Motor Theory (IC 105-IC 105) > Section: Assessments

Q: 100 Hertz is applied to an eight-pole squirrel-cage motor. What happens to the synchronous speed if the number of poles are reduced to four?
- It is half.
- It doubles.
- It is one-fourth.
- It is four times greater.
A: It is half.

Q: A start winding is also known as a(n)__________.
- shade-pole
- squirrel-cage
- auxiliary winding
- main winding
A: shade-pole

Q: A wound rotor motor will not start if ___________.
- a stator winding is open
- the rotor winding is open
A: a stator winding is open

Q: A(n) ___________ motor is a motor that has no physical electrical connection to the rotor.
- wound rotor
- universal
- induction
A: wound rotor

Q: After running at normal speed a wound rotor motor will stall if a rotor winding is opened.
- True
- False
A: False

Q: Interchanging the rotor leads of a wound rotor motor reverses the direction of the motor.
- True
- False
A: False

Q: The capacitor-start AC motor has a capacitor in ____________ with the _____________ winding.
- parallel, auxiliary
- series, auxiliary
- series, main
A: parallel, auxiliary

Q: The direction of rotation by the shaft of a universal motor can be changed by reversing the AC power leads.
- True
- False
A: False

Q: The direction of rotation of a three-phase motor can be reversed by ______________.
- reconnecting L1 to L2, L2 to L3 and L3 to L1
- disconnecting one of the leads and then reconnecting it after the motor is at full speed
- reversing any two of the three line connections
A: reconnecting L1 to L2, L2 to L3 and L3 to L1

Q: The direction of rotation of the shaded-pole induction motor is non-reversible.
- True
- False
A: True

Q: The number of wound rotor poles must be the same as the number of stator poles.
- True
- False
A: True

Q: The speed of the universal motor increases if the frequency of the AC power source increases.
- True
- False
A: True

Q: The speed regulation of a squirrel-cage motor is ______________.
- poor
- good
A: poor

Q: The starting torque of a split-phase induction motor is maximum when the current through the start and run coils are _________ degrees apart.
- 0
- 45
- 90
- 180
A: 0

Q: There is no current flow through the rotor of a squirrel-cage motor if the rotor is not turning.
- True
- False
A: False

Q: To change the direction of a capacitor-start AC induction motor, ______________.
- reverse the connections of the power line
- reverse either the main winding or auxiliary winding
- the direction cannot be changed
A: reverse the connections of the power line

Q: When a polyphase motor encounters a single-phase condition, only one of the three-phase leads is supplying power.
- True
- False
A: False

Q: When the DC excitation increases to cause an over-excited synchronous motor, a __________ is developed.
- lagging power factor
- leading power factor
- unity power factor
A: lagging power factor

Q: Which of the following factors determine the synchronous speed of an AC motor?
- inductance of the rotor windings
- the frequency of the applied voltage
- the number of field poles per phase
- the physical lead driven by the motor
- both b and c
A: inductance of the rotor windings

Q: Which of the following inductance motors use a centrifugal switch?
- resistance-start, induction-run
- capacitive-start, induction-run
- both a and b
A: resistance-start, induction-run

Q: Which of the following windings of a resistance-start AC motor will give the highest resistance reading?
- main
- auxiliary
A: main

Q: Which type of single-phase induction motor is used for hard-starting applications, such as for compressors?
- resistance-start
- capacitor-start
A: resistance-start

Q: Relating to Fig 1, the expected reading of DMM 1 when the motor is OFF is ______________ VAC.
A: 115

Q: Relating to Fig 1, the expected reading for DMM 2 when the motor is ON is ____________ VAC.
A: 460

Q: Relating to Fig 1, the expected reading of DMM 2 when the motor is OFF is ____________ VAC.
A: 460

Q: Relating to Fig. 1, the expected reading of DMM 1 when the motor is ON is __________ VAC.
A: 115

Q: Relating to Fig 2, the expected reading of DMM 1 when the motor is OFF is _____________ VAC.
A: 480

Q: Relating to Fig 2, the expected reading of DMM 2 when the motor is ON is ______________ VAC.
A: 277