ILT 115 Final Exam Review Questions with Revised Answers All Correct
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Course
ILT 115
Institution
ILT 115
ILT 115 Final Exam Review Questions with Revised Answers All Correct
Where is the best place to begin troubleshooting a DC drive system problem? Why? - Answer- the drive, because most have some sort of display, LED, or fault codes
List some safety steps that you should follow prior to workin...
ILT 115 Final Exam Review Questions
with Revised Answers All Correct
Where is the best place to begin troubleshooting a DC drive system problem? Why? -
Answer- the drive, because most have some sort of display, LED, or fault codes
List some safety steps that you should follow prior to working on a DC drive system. -
Answer- look, listen, smell, hover, be observant
Is it permissible to connect a DC drive to a supply voltage that is higher than the
nameplate rating of the drive? Why or why not? - Answer- it is permissible as long as
the supply voltage is within 10% of the nameplate rating, the problem with this is that if
there is voltage spikes at this higher voltage it could severely damage the drive
Give a brief description of phase imbalance. - Answer- during construction care is taken
to make sure that the loads are balanced but over time as it is not unusual for loading to
become unbalanced, this imbalance causes intermittent tripping of the controller which
can result in premature failure of certain components
True or False? An inoperable cooling fan can prevent a drive from operating. - Answer-
true
Describe the cooling problem created by using a variable speed drive to operate a
motor with a shaft-mounted fan. - Answer- if the fan shaft becomes stripped it will not
spin the fan and the motor will overheat, or some motors are innterlocked with a fan so
that they will not operate unless the fan is also on
Describe the dangers of using an insulation resistance tester on a DC drive system. -
Answer- failure to turn off the power from the motor leads will cause the tester to apply a
high voltage into the output section of the drive and damage the power semiconductors
Explain how the motor load can affect the performance of a DC drive. - Answer- the
load could cause the motor to draw an excessive amount of current for too long a time
and trip out the drive
True or False? When using shielded cable on feedback devices, you must ground the
shield wire at both ends of the cable. Explain your answer. - Answer- false, you should
only ground the shield at the drive cabinet
Describe any precautions that you should observe when routing the feedback cable
outside the drive cabinet. - Answer- it should be in a separate conduit, it should be
, routed at a right angle to power wires, it should not be near any high power contactors
or relays
Describe any precautions that you should observe when routing the feedback cable
inside the drive cabinet. - Answer- you should ground the shield inside of the drive
cabinet
Explain when it is permissible to readjust drive settings. - Answer- it is permissible to
readjust drive settings if it is a newly installed drive
Describe the purpose of the IR compensation adjustment. - Answer- it is used to sense
CEMF from the moor as an indication of motor speed, this adjustment matches the
motors characteristics to the drive
Explain when a DC drive should be returned to the manufacturer for repair. - Answer-
once you have completed testing the module and you cannot obtain the replacement
part
Another name for an AC drive is converter - Answer- false
The two major types of inverter drives are the - Answer- vsi and csi
The letters VVI stand for variable voltage inverter. - Answer- true
In a VVI, the DC voltage is uncontrolled. - Answer- false
A converter - Answer- is also known as a rectifier circuit.
An inverter - Answer- converts DC voltage in to a pulsating DC voltage.
The V/Hz ratio is needed to maintain proper operation of the motor. - Answer- true
A Phase control bridge rectifier utilizes diodes to provide a constant current to the
inverter section. - Answer- false
A vector represents both __________ and __________. - Answer- magnitude and
direction
What is the term used to describe the "jumping ahead" of the artificial AC in a flux vector
drive? - Answer- step change
What are the two speeds that are associated with an induction motor? - Answer-
synchronous speed and rotor speed
Explain the difference between the two speeds associated with an induction motor. -
Answer- Synchronous speed is the speed at which the rotating magnetic field revolves
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