maintenance
protection
functions of mechanisms
misc.
Diagrams
100
In a casual inspection of a DC motor, you notice new grooves cut in its commutator just down to the mica. The first thing you do(aside from the normal safety procedures) is
A.) immediately take the motor out of service and replace it
B.) hand stone the commutator
C.) log the problem and have the commutator replaced as scheduled maintenance
D.) inspect the brushes for dirt, defects, and wear, then clean and replace as necessary
D.) inspect the brushes for dirt, defects, and wear then clean and replace as necessary
100
In a motor circuit, which of the following devices provides short-circuit protection?
A.) Overload relay
B.) Overspeed switch
C.) Fuses or circuit breaker
D.) Thermak overloads
C.) Fuses or circuit breaker
100
Current-limiting Fuses are best for electrical circuits capable of producing high
A.) voltage surges
B.) resistance
C.) voltage
D.) fault currents
D.) fault currents
100
The primary winding of a transformer is rated at 115 volts and the secondary is rated at 300 volts. The primary winding has 500 turns. How many does the secondary have?
A.) 1100
B.) 1200
C.) 1300
D.) 1500
C.) 1300
100
There are three single phase transformers connected to form a 3-phase transformer bank. The connection shown at left is a
A.) Delta-Delta
B.) Wye-Wye
C.) Delta-Wye
D.) Wye-Delta
C.) Delta-Wye
200
You observe a DC motor with a ticking sound that corresponds with a discolored commutator bar rotating under the brushes. You log the error and suggest there is
A.) an open commutator bar
B.) a bearing ready to fail
C.) poor coupling alignment
D.) brush rigging not on electrical neutral
A.) an open commutator bar
200
Short circuits in any system are always accompanied by a sudden
A.) voltage decrease
B.) current decrease
C.) voltage increase
D.) resistance increase
A.) voltage decrease
200
If the primary coil of a transformer has more turns than the secondary, it is a
A.) step-down transformer
B.) step-up transformer
C.) variable transformer
D.) Fixed transformer
A.) step-down transformer
200
With 480 volts primary voltage, what would be the primary current at full load for a secondary full load of 11.2 amps at 240 volts?
A.) 7.0 amps
B.) 5.6 amps
C.) 3.2 amps
D.) 22.4 amps
B.) 5.6 amps
200
Which of the symbols shown above is a relay contact?
A.) 1
B.) 2
C.) 3
D.)7
E.) 8
A.) 1
300
When greasing a motor the worst thing over-greasing does is
A.) cause a fire hazard
B.) unbalance the motor armature
C.) break down winding insulation
D.) cause the bearing to run hotter than normal
C.) break down winding insulation
300
To prevent damage to a current transformer, the secondary winding must be
A.) open
B.) disconnected
C.) short-circuit
D.) insulated
C.) short-circuited
300
Dynamic braking of a shunt DC motor is done by
A.) connecting a resistance across the field
B.) connecting a resistance across the armature
C.) connecting a resistance across the armature and removing the field
D.) having a permanent resistance across the armature and removing the field
B.) connecting a resistance across the armature
300
A hickey is used for
A.) bending conduit
B.) marking wires
C.) indenting lugs
D.) stripping cable
A.) bending conduit
300
What is the steady state value of current in AMPs flowing through the 10 ohm resistor in the circuit shown above?
A.) 1.3
B.) 1
C.) 0
D.) 3.33
C.) 0
400
When a DC motor does not come up to speed the
A.) field is too strong or the motor is oversized
B.) field is too strong or the motor terminal voltage is too low
C.) motor is oversized
D.) motor terminal voltage is too low or the motor is oversized
B.) field is too strong or the motor terminal voltage is too low
400
Which of the following is the best way to identify control panel wires?
A.) Use voltage control diagrams
B.) Use control schematics
C.) Use wire markers
D.) Mark terminal blocks
C.) Use wire markers
400
A transducer will
A.) open an oil circuit breaker when a trip signal is present
B.) remove voltage spikes on a transmission line
C.) provide lightning protection
D.) provide feedback
D.) provide feedback
400
Because of the manner in which a voltmeter is used, it must have
A.) low resistance
B.) high resistance
C.) a multiplier in parallel
D.) a movement that I indicated plus or minus values
B.) high resistance
400
Which of the symbols above are thermal overload contacts?
A.) 4
B.) 5
C.) 6
D.) 7
E.) 8
C.) 6
500
Proper alignments between shafts can be checked with a
A.) straightedge
B.) feeler gauge
C.) straightedge and feeler gauge
D.) caliper
C.) straightedge and feeler gauge
500
The purpose of an arc chute over a contactor on a panel board is to
A.) keep the dirt away from the contactor
B.) keep the contactor aligned
C.) protect your eyes
D.) help extinguish the electric arc
A.) keep the dirt away from the contactor
500
What will happen to a shunt motor if a shunt field coil opens while the motor is running under light load?
A.) It runs away
B.) It runs at the same speed
C.) It runs slower
D.) It stops
A.) It runs away
500
Typical PLC programs are written in which one of the following languages
A.) Basic
B.) C++
C.) Pascal
D.) Ladder logic
D.) Ladder logic
500
What is the current flow through the 3 ohm resistor in the circuit shown above?
A.) 1.3 A
B.) 4 A
C.) 6 A
D.) 8 A
B.) 4 A