NCCER 26410-20 MOTOR OPERATION
AND MAINTENANCE EXAM
the loss of a single phase of a polyphase motor can cause - Correct Answers -failure of
the remaining phase windings
the useful life of a squirrel cage induction motor depends largely on the condition of its -
Correct Answers -insulation
an autotransformer is one of the methods used to - Correct Answers -reduce startup
current
NEMA's usual service conditions include a frequency variation of NOT more than __%
of the nameplate frequency - Correct Answers -5%
which of the following factors affects the frequency and thoroughness of motor
maintenance and testing? - Correct Answers -nature of service
a motor's rotating speed can be determined using a - Correct Answers -tachometer
when a motor is powered down, unusual bearing noise may be detected by using a -
Correct Answers -stethescope
absorption current consists of polarization current and - Correct Answers -electron drift
the frequency of motor lubrication depends on the type of bearing, motor application,
and - Correct Answers -service environment
for winding resistance tests, the test voltage is applied for _____ or until the reading is
essentially stable - Correct Answers -1 minute
the two typical types of motor couplings are - Correct Answers -jaw and splined
the minimum acceptable rating for equipment rated at 1000V or less is __ - Correct
Answers -1 megaohm
typical materials used in a Class H insulation system include - Correct Answers -silicone
elastomer
AND MAINTENANCE EXAM
the loss of a single phase of a polyphase motor can cause - Correct Answers -failure of
the remaining phase windings
the useful life of a squirrel cage induction motor depends largely on the condition of its -
Correct Answers -insulation
an autotransformer is one of the methods used to - Correct Answers -reduce startup
current
NEMA's usual service conditions include a frequency variation of NOT more than __%
of the nameplate frequency - Correct Answers -5%
which of the following factors affects the frequency and thoroughness of motor
maintenance and testing? - Correct Answers -nature of service
a motor's rotating speed can be determined using a - Correct Answers -tachometer
when a motor is powered down, unusual bearing noise may be detected by using a -
Correct Answers -stethescope
absorption current consists of polarization current and - Correct Answers -electron drift
the frequency of motor lubrication depends on the type of bearing, motor application,
and - Correct Answers -service environment
for winding resistance tests, the test voltage is applied for _____ or until the reading is
essentially stable - Correct Answers -1 minute
the two typical types of motor couplings are - Correct Answers -jaw and splined
the minimum acceptable rating for equipment rated at 1000V or less is __ - Correct
Answers -1 megaohm
typical materials used in a Class H insulation system include - Correct Answers -silicone
elastomer
