study guide Flashcards
Most new or upgraded DC systems use what type of starting method?
Select one:
a.
contactor
b.
electronic DC drive
c.
rheostat
electronic dc drive
When starting a DC motor with a rheostat, the current at the field winding is ? and the current at the armature is ? .
Select one:
a.
high / high
b.
high / low
c.
low / high
high/low
During the operation of a DC rheostat motor starter, the resistance is ? in the field winding and ? in the armature until the motor is brought up to full speed.
Select one:
a.
increased / increased
b.
increased / reduced
c.
reduced / increased
increased/reduced
Most DC motor contactors consist of ? set(s) of contacts.
Select one:
a.
one
b.
two
c.
three
one
Arc chutes typically absorb ? than 80% of the energy released during the interruption of current flow as the contacts open.
Select one:
a.
greater
b.
less
greater
The magnetic ? coil produces a magnetic field between the breaking contacts that forces the arc up, increasing the length of the arc and causing it to dissipate faster.
Select one:
a.
blowout
b.
contactor
c.
overload
blowout
When analog control devices are located large distances from each other, which type of signal is preferable for installing the control wiring?
Select one:
a.
Current
b.
Voltage
current
? are analog output devices that document industrial and commercial process data .
Select one:
a.
Control valves
b.
Recorders
c.
Ultrasonic flow meter
recorders
AC, DC, and transistor-to-transistor logic (TTL) are the three most common types of output circuits used in controller ? modules.
Select one:
a.
input
b.
output
output
Controller input and output modules have opto-isolation between the field device power and the controller or motor drive system power to eliminate noise and operational problems.
Select one:
True
False
true
Speed and ? are two physical quantities that must be controlled in a motor drive.
Select one:
a.
direction
b.
temperature
c.
torque
torque
Motor control systems that control motor speed without feedback data for torque or speed are called ? control systems.
Select one:
a.
closed-loop
b.
open-loop
open loop
A motor control system that uses a tachometer to control the speed of the motor is called a(n) ? system.
Select one:
a.
closed-loop
b.
open-loop
closed loop
Drive, comparator, sensor, and amplifier are the four parts of a(n) ? system.
Select one:
a.
closed-loop
b.
open-loop
closed loop
Tachometer/generators and optical encoders are two types of devices that are generally used to provide speed reference signals in a(n) ? speed control system.
Select one:
a.
closed-loop
b.
open-loop
closed loop
In a closed-loop speed control system, the ? is the desired speed selected for the motor connected to the drive.
Select one:
a.
feedback speed value
b.
feedback summing amplifier
c.
set point speed value
set point value
The architecture of the PC and PLC systems are similar with both featuring a motherboard, memory, expansion slots, and a(n) ? .
Select one:
a.
HMI
b.
monitor
c.
processor
processor
Which IEC standard programming language most closely replicates the control diagrams used in traditional magnetic motor control?
Select one:
a.
Function block diagrams
b.
Instruction list
c.
Ladder logic
d.
Sequential function charts
e.
Structured text
ladder logic
Three-phase motors typically have slip, which is the difference between the rotational speed of the rotor of the motor and the rotational speed of the magnetic field in the stator of the motor. What is the slip of a synchronous motor?
Select one:
a.
0 (zero)
b.
3%
c.
5%
zero
? in synchronous motors have two winding types, salient pole windings and amortisseur windings.
Select one:
a.
Rotors
b.
Stators
rotors
What is the highest level of factory floor network architecture and provides an information layer for enterprise-wide data collection and program maintenance network?
Select one:
a.
ControlNet
b.
DeviceNet
c.
Ethernet
ethernet
A specification for an Ethernet® network calls for a 100BaseT system. What type of cable would be used for this network?
Select one:
a.
Coaxial cable
b.
Fiber-optic cable
c.
STP (shielded twisted pair)
d.
UTP (unshielded twisted pair)
utp
All ? cable systems include device power and data integrated into a single cable system.
Select one:
a.
ControlNet
b.
DeviceNet
c.
Ethernet
DeviceNet
Both ControlNet and flat cable DeviceNet require cable terminators or end terminators to prevent data signals from reflecting back through the cable.
Select one:
True
False
True
Which troubleshooting technique is generally divided into two groups called power and information?
Select one:
a.
Block diagrams
b.
Bracketing
c.
Information funneling
d.
Signal flow
signal flow
Which basic troubleshooting technique includes four levels of testing?
Select one:
a.
Block diagrams
b.
Bracketing
c.
Information funneling
d.
Signal flow
information funneling
A ? relay is a relay that not only maintains its contacts in the last position without a continuously energized coil, but also with a mechanical mechanism or remnant magnetism until it resets electrically.
a.
frequency
b.
latching
c.
sequencing
latching
? latching relays have a latch coil and an unlatch coil.
a.
Impulse
b.
Magnetic
c.
Mechanical
mechanical
The coils of mechanically latching relays are rated for continuous operation.
Select one:
True
False
False
? have contacts that prevent continuous power from being applied to the coil after it has been energized.
a.
Coil clearing contacts
b.
Holding contacts
c.
Overload contacts
coil clearing contacts
Wound rotor motor speed control is accomplished by inserting resistors in series with the ? winding of the motor.
a.
rotor
b.
run
c.
stator
rotor
To operate a wound rotor motor at full speed, the rotor windings must be ? .
a.
connected
b.
open
c.
shorted together
shorted together
Single-phase motor speed control circuits use SCR or ? to control power to the motor for speed control.
a.
diacs
b.
diodes
c.
triacs
triacs
In a single-phase motor speed control, the thyristor controls power in the circuit by changing the ? angle of the AC sine wave that drives the motor.
a.
displacement
b.
firing
c.
phase
firing
A variable frequency drive provides a 48 hertz AC voltage to a 3-phase AC motor that has four poles per phase. What would be the synchronous speed of the motor with this voltage applied?
a.
1280 RPM
b.
1440 RPM
c.
1800 RPM
1440
hertz X 120 divided by the number of poles
In a VFD, the ? section of the VFD converts the incoming AC voltage into rectified DC voltage.
a.
converter
b.
DC bus
c.
inverter
converter
