NEIEP 400 Final Review
A ____ generator's pole pieces become excited by residual magnetism . - ANS-Self - excited
A light electrical load on a commutator causes which of the following conditions ? -
ANS-Threading
A minus sign in front of a reading of the digital voltmeter indicates which of the following ? -
ANS-The positive lead is connected to the negative source
What kind of bearing is lubricated with a slinger ring? - ANS-Sleeve A transformer has 728
turns on the primary winding and 56 turns on the secondary With 120 volts applied on the
primary , what is the output voltage on the secondary ? - ANS-9.23 volts
A transformer has a primary voltage of 440 V with 100 turns and a 15 : 1 voltage ratio of
transformation . With a primary current of 25 amps , what is the current in the secondary ? -
ANS-375 amps
An electromagnetic field in a generator is created by having current flow in the ___? -
ANS-Coils wound around the pole piece
How can an eccentric commutator be corrected ? - ANS-Turning the commutator with a lathe
tool
How is an armature shaft balanced at the factory or repair facility - ANS-Adding or removing
epoxy weights to the shaft or windings
How is motor speed changed ? - ANS-By varying the field or armature voltage
How many parts make up a DC machine's shaft? - ANS-1 If a current carrying wire is placed
perpendicular to a field created by two magnets of opposite polarity , what happens ? -
ANS-The conductor is moved at a right angle to the flux from the magnetic poles
If a squirrel cage motor rotation is clockwise with ACB phase sequence and the phase
sequence ABC is applied , which statement is correct ? - ANS-The motor will run in the
counterclockwise direction
In a DC series generator - ANS-Current flows only when there is a load
In a separately - excited generator , where does field excitation current come from ? - ANS-An
external power source
Mica is used as a / an ___? - ANS-Insulator
More loops are added to the elementary DC generator armature in order to help it do what ? -
ANS-Reduce ripple
Take a look at the image. What type of transformer is represented ? - ANS-Core type with a
wye primary and delta secondary
Refer to the figure . What will be the phase relationship between the primary and secondary
voltages ? - ANS-The secondary voltage will be 180 ° out of phase .
Refer to the figure . Which of the following statements is true regarding the section of wire with
current flow as pictured ? As seen from the left end, the conductor's magnetic field would rotate
counterclockwise. Image: ANS Refer to the figure . Which statement is correct ? Quesiton
Image - ANS-Each phase follows the other by 60 °
A ____ generator's pole pieces become excited by residual magnetism . - ANS-Self - excited
A light electrical load on a commutator causes which of the following conditions ? -
ANS-Threading
A minus sign in front of a reading of the digital voltmeter indicates which of the following ? -
ANS-The positive lead is connected to the negative source
What kind of bearing is lubricated with a slinger ring? - ANS-Sleeve A transformer has 728
turns on the primary winding and 56 turns on the secondary With 120 volts applied on the
primary , what is the output voltage on the secondary ? - ANS-9.23 volts
A transformer has a primary voltage of 440 V with 100 turns and a 15 : 1 voltage ratio of
transformation . With a primary current of 25 amps , what is the current in the secondary ? -
ANS-375 amps
An electromagnetic field in a generator is created by having current flow in the ___? -
ANS-Coils wound around the pole piece
How can an eccentric commutator be corrected ? - ANS-Turning the commutator with a lathe
tool
How is an armature shaft balanced at the factory or repair facility - ANS-Adding or removing
epoxy weights to the shaft or windings
How is motor speed changed ? - ANS-By varying the field or armature voltage
How many parts make up a DC machine's shaft? - ANS-1 If a current carrying wire is placed
perpendicular to a field created by two magnets of opposite polarity , what happens ? -
ANS-The conductor is moved at a right angle to the flux from the magnetic poles
If a squirrel cage motor rotation is clockwise with ACB phase sequence and the phase
sequence ABC is applied , which statement is correct ? - ANS-The motor will run in the
counterclockwise direction
In a DC series generator - ANS-Current flows only when there is a load
In a separately - excited generator , where does field excitation current come from ? - ANS-An
external power source
Mica is used as a / an ___? - ANS-Insulator
More loops are added to the elementary DC generator armature in order to help it do what ? -
ANS-Reduce ripple
Take a look at the image. What type of transformer is represented ? - ANS-Core type with a
wye primary and delta secondary
Refer to the figure . What will be the phase relationship between the primary and secondary
voltages ? - ANS-The secondary voltage will be 180 ° out of phase .
Refer to the figure . Which of the following statements is true regarding the section of wire with
current flow as pictured ? As seen from the left end, the conductor's magnetic field would rotate
counterclockwise. Image: ANS Refer to the figure . Which statement is correct ? Quesiton
Image - ANS-Each phase follows the other by 60 °
