Motors Book - Chapter 7
15 Questions
| Total Attempts: 203
Questions and Answers
- 1.The ___ is constructed of laminated iron sheets to minimize eddy current losses.
- A.
Brush
- B.
Discharge resistor
- C.
Slip ring
- D.
Stator
- 2.___ windings, or damper windings, are squirrel-cage conducting bars placed in slots on the pole faces and connected at the ends.
- A.
Magnetic
- B.
Pony
- C.
Amortissuer
- D.
Field
- 3.Synchronous motors that typically run faster than about ___ are considered high-speed synchronous motors.
- A.
450 mph
- B.
450 rpm
- C.
1,000 mph
- D.
1,000 rpm
- 4.When ___ are used, the rotors do not need to be excited.
- A.
Static exciters
- B.
Permanent magnets
- C.
Brushless exciters
- D.
Motor-generator sets
- 5.The ___ typically is a shunt- or compound-wound DC generator with the armature in parallel with the shunt field and its shunt-field rheostat.
- A.
Exciter generator
- B.
Servomotor
- C.
Motor-generator
- D.
Slip ring
- 6.___ rotors are simpler than excited rotors and have minimal maintenance requirements.
- A.
Squirrel-cage
- B.
Wound-rotor
- C.
Permanent magnet
- D.
None of the above
- 7.A ___ exciter is an AC generator and rectifier mounted on a motor shaft.
- A.
Bearing
- B.
Pony
- C.
Thermal
- D.
Brushless
- 8.A common type of relay used with synchronous motors is a(n) ___ relay.
- A.
Polarized field frequency
- B.
Loss-of-excitation (field-failure)
- C.
Out-of-step
- D.
All of the above
- 9.A(n) ___ relay is an overload relay that is used to protect a synchronous motor from damage induced currents caused by the rotor falling out of step with the rotating stator field.
- A.
Out-of-step
- B.
Loss-of-excitation
- C.
Synchronous overload
- D.
Discharge
- 10.A(n) ___ resistor is a resistor used to discharge any AC potential that builds up in the amortisseur winding of a rotor in a synchronous motor.
- A.
Direct
- B.
Discharge
- C.
Winding
- D.
Amortisseur
- 11.The simplest starting method for a synchronous motor is ___ starting, where the motor is wired directly across the line conductors.
- A.
Reduced-voltage
- B.
Direct online (DOL)
- C.
Low-speed
- D.
High-speed
- 12.The type of torque that is important to understand for synchronous motors is ___ torque.
- A.
Reluctance
- B.
Pull-in
- C.
Pull-out
- D.
All of the above
- 13.___ torque is the maximum torque required to accelerate a synchronous motor into synchronization at the rated voltage and frequency.
- A.
Reluctance
- B.
Pull-out
- C.
Pull-in
- D.
Field
- 14.___ torque is provided by the interaction of the stator field and the rotor field windings.
- A.
Synchronous
- B.
Excitation
- C.
Lagging
- D.
Starting
- 15.The power factor of a synchronous motor is determined by the amount of ___ power applied to the rotor.
- A.
AC
- B.
True
- C.
DC
- D.
Apparent
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