Motor Control II Flashcards
A ? is a semiconductor that converts AC voltage into DC voltage. This process is called ?.
A) diode/rectification
B) peak inverse voltage
C) LED/LED
D) optocoupler/electrically isolates
diode/rectification
A diode will be destroyed when the reverse bias voltage is above the?
A) diode/rectification
B) peak inverse voltage
C) LED/LED
D) optocoupler/electrically isolates
peak inverse voltage
An ? is a diode which radiates light when it is forward biased. Know the symbol for an ?
A) diode/rectification
B) peak inverse voltage
C) LED/LED
D) optocoupler/electrically isolates
LED/LED
An ? is a semiconductor which ? two circuits from each other.
A) diode/rectification
B) peak inverse voltage
C) LED/LED
D) optocoupler/electrically isolates
optocoupler/electrically isolates
A ? is a semiconductor used for ?.
A) zener diode/ voltage regulation
B) Diffuse scan/direct scan/polarized scan
C) rapidly changing input signals
D) single-phase AC motors
zener diode/ voltage regulation
?, ?, and ? are all methods used by photoelectric scanner to sense objects.
A) zener diode/ voltage regulation
B) Diffuse scan/direct scan/polarized scan
C) rapidly changing input signals
D) single-phase AC motors
Diffuse scan/direct scan/polarized scan
-Know how these three methods operate. Pages 194-196 textbook.
Solid state relays are a semiconductor replacement for mechanical relays. Solid state relays are vulnerable to ? which may cause intermittent or erratic operation.
A) zener diode/ voltage regulation
B) Diffuse scan/direct scan/polarized scan
C) rapidly changing input signals
D) single-phase AC motors
rapidly changing input signals
Reduced voltage starting is commonly used with DC motors and 3-phase motors. It is not commonly used with ?.
A) zener diode/ voltage regulation
B) Diffuse scan/direct scan/polarized scan
C) rapidly changing input signals
D) single-phase AC motors
single-phase AC motors
Reduced voltage starting of a DC motor is commonly done with a ? or a ?.
A) rheostat (variable resistor)/solid-state starter
B) verify the input and output conditions
C) directly open power leads
rheostat (variable resistor)/solid-state starter
The first step to troubleshooting a malfunctioning programmable logic relay is to ? are within specs.
A) rheostat (variable resistor)/solid-state starter
B) verify the input and output conditions
C) directly open power leads
verify the input and output conditions
Phase sequence relays are low current devices which monitor three-phase voltages. They are commonly used to open control circuits, provide delays, and turn on alarm lights. They do not ?.
A) rheostat (variable resistor)/solid-state starter
B) verify the input and output conditions
C) directly open power leads
directly open power leads
Recall back to our previous lessons about breaking. Know what dynamic, flux, injection, and regenerative breaking systems are and how they function. See page 287 in the textbook.
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Special ? must be used to protect an SSR in a shorted condition.
Select one:
a.
met-oxide varistors
b.
semiconductor fuses
c.
zener diodes
B
The ? should be used to install, operate, or maintain an MCC.
Select one:
a.
manufacturer’s manuals
b.
NEC
c.
project specifications
A
The fault current withstand rating of an MCC is determined by the highest rated device within the MCC.
Select one:
True
False
False
In corrosive atmospheres, copper buses in MCCs are often coated with ? to protect the bus from corrosion.
Select one:
a.
carbon
b.
tin
c.
zinc
B
? are one of the best options when maximum starting torque and minimum starting current are required for a particular application.
Select one:
a.
Autotransformer starters
b.
Part-winding starters
c.
Primary resistor starters
d.
Soft-start starters
e.
Solid-state reduced voltage starters
Incorrect
f.
Wye-delta starters
A
In applications that require frequent starting or long acceleration periods, a(n) ? would work very well.
Select one:
a.
autotransformer starter
b.
part-winding starter
c.
primary resistor starter
d.
soft-start starter
e.
solid-state reduced voltage starter
f.
wye-delta starter
A
Swapping any two power phase leads will reverse the direction of a three-phase motor.
Select one:
True
False
True
The industry standard for reversing a three-phase motor is to switch which two power leads?
Select one:
a.
L1 (phase A) and L2 (phase B)
b.
L1 (phase A) and L3 (phase C)
Correct
c.
L2 (phase B) and L3 (phase C)
B
The ? value is the number of time units a programmed timer is programmed to count before timed contacts change state.
Select one:
a.
accumulated
b.
preset
c.
time base
B
The ? value is the current number of time units a programmed timer has counted after the timing period has been initiated.
Select one:
a.
accumulated
b.
preset
c.
time base
A
? latching relays have a latch coil and an unlatch coil.
Select one:
a.
Impulse
b.
Magnetic
c.
Mechanical
C
? type latching relays have a single coil that operates a cam mechanism to change the state of the contacts each time the coil is energized (pulsed) for a minimum of 50 milliseconds.
Select one:
a.
Impulse
b.
Magnetic
c.
Mechanical
A
? have contacts that prevent continuous power from being applied to the coil after it has been energized.
Select one:
a.
Coil clearing contacts
b.
Holding contacts
c.
Overload contacts
A
? relays are solid-state devices that simultaneously monitor each phase of a 3-phase circuit for various failures.
Select one:
a.
Frequency
b.
Phase sequence
c.
Voltage sensing
B
Loss of a phase, overvoltage, undervoltage, and out of sequence (phase rotation) are conditions that can be detected by ? sequence relays.
Select one:
a.
frequency
b.
phase
c.
voltage sensing
B
A ? relay is a solid-state device that monitors a single-phase voltage and will change output contact status when a deviation from nominal frequency is detected.
Select one:
a.
frequency
b.
phase sequence
c.
voltage sensing
A
? are electronic devices that monitor an AC or DC voltage and provide an output if that voltage is out of specification.
Select one:
a.
Frequency relays
b.
Phase sequence relays
c.
Voltage sensors
C
? counters accumulate input pulses from two inputs and provide an output after the preset count value is reached, one input adds counts and one input subtracts counts from the accumulated total.
Select one:
a.
Mechanical
b.
Up
c.
Up/down
C
Wound rotor motor speed control is accomplished by inserting resistors in series with the ? winding of the motor.
Select one:
a.
rotor
b.
run
c.
stator
A
To operate a wound rotor motor at full speed, the rotor windings must be ? .
Select one:
a.
connected
b.
open
c.
shorted together
C
Phase current to a VFD motor load should vary no more than ? in each phase.
Select one:
a.
2%
b.
5%
c.
10%
C
? are well-suited for switching operations.
Select one:
a.
JFETs
b.
Optocouplers
c.
Zeners
A
A ? has three leads, identified as drain, source, and gate.
Select one:
a.
BJT
b.
JFET
c.
SCR
B
A(n) ? is used to provide a signal between two electrically isolated circuits.
Select one:
a.
optocoupler
b.
phototransistor
c.
SCR
A
Capacitive, inductive and ultrasonic are three types of ? sensors that are based on the sensor’s operating principles.
Select one:
a.
analog
b.
contact
c.
photoelectric
d.
proximity
D
What is the photoelectric scanning method in which the transmitter and receiver are placed opposite each other?
Select one:
a.
Diffuse
b.
Direct
c.
Polarized
d.
Retroreflective
B
? devices are solid-state sensors that detect the presence of a magnetic field.
Select one:
a.
Capacitive
b.
Hall effect
c.
Inductive
d.
Ultrasonic
B
