True/False
Indicate whether the
statement is true or false.
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1.
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Mechanical type brakes cannot hold a suspended load.
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Figure 30-2 
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2.
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In the accompanying figure, the brake is applied automatically when the motor is
not operating.
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3.
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Dynamic braking for a DC motor is very effective, but the braking effect becomes
weaker as the armature slows down.
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4.
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Plugging is used with direct current motors more than with three phase squirrel
cage motors.
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5.
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One method of providing plugging control is with the use of an automatic timed
circuit.
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Completion
Complete each
statement.
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6.
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Mechanical brakes can be obtained in two basic types: drum and
____________________.
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7.
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The principle of dynamic braking for a direct current motor is to change the
motor into a(n) ____________________.
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8.
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When a generator produces electrical power, it produces ____________________,
making the armature hard to turn.
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9.
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Dynamic braking circuits for alternating current motors generally include a(n)
______________________________ to lower the voltage to the rectifier.
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10.
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____________________ is defined by NEMA as a system of braking, in which the
motor connections are reversed so that the motor develops a counter torque that acts as a retarding
force.
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Short Answer
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11.
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Why is dynamic braking sometimes referred to as magnetic braking?
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12.
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How is dynamic braking for a DC motor accomplished?
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13.
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What are the three factors that determine induced voltage?
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14.
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How is plugging accomplished with three phase motors?
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15.
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What is the most accurate method of plug stopping a motor?
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