NCCER Electrical 2 Module2

In a DC motor the armature turns and cuts through the lines of magnetic force produced by the _____.

• Field poles

• Brushes

• Commutator

• Rotor

Which of the following is TRUE regarding the neutral plane in a single-loop DC motor?

• In the neutral plane, the loop is parallel to the magnetic field.

• At this position, the commutator connects to the brushes.

• The neutral plane allows the motor to be self-starting.

• No torque is produced in the neutral plane.

Which of the following motors is the BEST choice for an application requiring adjustable speeds?

• Shunt DC

• Split-phase AC

• Capacitor-start AC

• Synchronous

The approximate horsepower of a 15,00W DC motor is ___.

• 10hp

• 20hp

• 30hp

• 40hp

A polyphase synchronous motor has three stator windings that are _____.

• 180° apart

• 120° apart

• 90° apart

• 45° apart

Which of the following motors is used to provide high starting torque and constant speed under load?

• Brushless

• Shunt

• Series

• Compound

For a given number of poles, which of the following determines the speed of an AC motor?

• Frequency

• Current

• Voltage

• Frame size

The synchronous speed at which a four pole, 50 Hz induction motor operates is ___.

• 1,200 rpm

• 1,500 rpm

• 1,800 rpm

• 2,000 rpm

The speed of a three phase squirrel cage induction motor is controlled by the frequency of the applied voltage and the _____.

• Diameter of the core

• Shaft length

• Number of poles

• Brush voltage

A wound-rotor induction motor is used _____.

• For speed control and to limit starting current

• To start low inertia loads

• When reduced slip is required

• To increase power factor