Exam (elaborations)
Electrical (Electrical) - Motors ! Part 2
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Electrical (Electrical) - Motors ! Part 2
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Electrical (Electrical) - Motors ! Part 2The synchronous speed at which a four-pole. 60Hz induction motor operates
is _________ rpm.
a. 6,900
b. 2,500
c. 1,140
d. 1,800 ✔️ 1,800
The most common service factor appearing on a motor's nameplate is:
a. 115
b. 1.15
c. 2
d. 1.5 ✔️ 1.15
The _______represent(s) the stationary magnet of a DC motor.
a. armature
b. rotor
c. commutator
d. field poles ✔️ field poles
The _______ DC motor is used where the required starting torque is high and
speed control is desirable.
a. compound
b. series
C. brushless
d. shunt ✔️ compound
Of the following motors, a _______ motor is the best installation choice for an
application requiring adjustable speeds.
a. DC
b. capacitor-start
c. synchronous
d. split-phase ✔️ DC
A ________ motor provides constant speed from no-load conditions to full-load
conditions.
a. series DC
, b. squirrel cage induction
e. shunt DC
d. synchronous ✔️ synchronous
Motor circuits are covered in
a. NEC Article 500
b, NEC Article 250
c. NEC Article 430
d. NEC Article 300 ✔️ NEC Article 430
Any exposed live parts operating at or more than ______ between terminals
must be guarded
a. 240V
b. 50V
C. 15V
d. 600V ✔️ 50V
The value indicated in rpm on the nameplate is the _________.
a. duty rating
b. rated full-load speed
c. power factor
d. rated horsepower ✔️ rated full-load speed
The two ways of varying the speed on a DC shunt motor is to adjust the
voltage and current on the field winding or the __________.
a. armature
b. stator
c. rheostat
d. controller ✔️ armature
For a constant-torque load the horsepower increases and decreases _____.
a. in inverse proportion to the speed
b. as the cube of the speed
c. as the square of the speed
d. in direct proportion to the speed ✔️ in direct proportion to the speed
The name of the motor part that rotates during operation is the:
a. stator
b. shunt/capacitor
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