True/False
Indicate whether the
statement is true or false.
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1.
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A DC motor is generally operated at or below normal speed.
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2.
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The shunt field power supply is generally designed to remain turned on even when
the main (armature) power supply is turned off.
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3.
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If current flow through the shunt field is interrupted, a compound wound, DC
motor will become a series motor and race to high speeds.
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4.
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The armature of a large DC motor has high resistance.
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5.
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If load is added to a motor, the motor speed increases.
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Completion
Complete each
statement.
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6.
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Speed control of a DC motor is much smoother if two separate
____________________, which convert the AC voltage to DC voltage, are used to control the motor
instead of resistors connected in series with the armature.
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7.
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Output voltage control is achieved by ____________________ the SCRs.
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8.
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The greatest advantage of using direct current motors is their variable
____________________ characteristic.
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9.
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A very common method of detecting motor speed is with the use of a(n)
____________________.
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10.
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An electrotachometer is connected to the ____________________.
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Short Answer
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11.
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How is normal speed for a DC motor obtained?
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12.
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How is a DC motor operated below normal?
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13.
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In a field failure control, what happens if the voltage falls below a certain
level?
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14.
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Why do most solid-state DC motor controls use some method to limit the current
to a safe value?
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15.
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What is an electrotachometer?
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