Motors: Theory and Application

Any exposed live parts must be guarded if they are operating at _____.

• 15V or more between terminals

• 50V or more between terminals

• 240V or more between terminals

• 600V or more between terminals

Which of the following is most likely to use dynamic braking?

• Circular saw

• Forklift

• Machine tool

• Safety brake

Tags

NGSS.HS-PS3-3

In a DC series motor, how much of its full-load torque is developed at starting?

• 50%

• 100%

• 250%

• 500%

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

• Voltage

• Current

• Frequency

• Frame size

Which of the following motors is used when the required starting torque is high and speed control is desirable?

• Brushless

• Compound

• Series

• Shunt

The synchronous speed at which a four-pole, 60Hz induction motor operates is _____.

• 1,140 rpm

• 1,800 rpm

• 2,500 rpm

• 6,900 rpm

Tags

NGSS.HS-PS3-5

A typical constant-torque load would be a(n) _____.

• conveyor

• centrifugal fan

• pump

• blower

Horsepower is used to rate the _____.

• length of operation of a motor

• synchronous speed of a motor

• output capacity of a motor

• thermal protection of a motor

A medium-size motor has a frame number of 284T. The D dimension of this motor is _____.

• 2"

• 5"

• 7"

• 10"

In a split-phase motor, how much greater is the starting current when compared to the full load current?

• 2 to 4 times

• 5 to 7 times

• 6 to 8 times

• 8 to 10 times