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WorksheetsIntro to Variable Frequency AC Drives Mod 1
Total questions: 21
Worksheet time: 11mins
Two common types of variable speed AC drives are General-Purpose and _________________ drives.
Servo
Vector
Inverter
Looping
The __________________ section of a general-purpose drive uses rectifiers to convert AC to DC
Inverter
Armature
Converter
transformer
A(n) ____________________ drive includes a feedback device to provide speed and direction feedback.
Feedback
Vector
Half-load
Alternating
One of the disadvantages of using an AC drive and motor instead of a DC drive and motor is that the AC motor cannot match the DC motor's _______________ torque.
Lineup
Stopping
Starting
Braking
DC motors are usually heavier and larger that three-phase motor of equivalent _____________________.
Power
Horsepower
Current
Load
In many applications, ________________ controls are required to control a variable speed drive.
Internal
External
Output
input
Common inputs to a variable frequency drive include manual inputs, ______________ devices, potentiometers, and PLCs
Proximity
Output
Automatic
Speed
Variable frequency drives provide inputs for line power and _______________ for the motor.
Inputs
Outputs
Voltage
Current
Some drives include _______________________ that can be used to turn on external devices such as an indicator light.
Input Relays
Frequencies
Output relays
Clutches
The user of a variable frequency drive can select what signal will provide the ______________- command
Speed
Stop
Brake
Output
Most variable frequency drives allow the use of manual inputs to __________________ a motor.
Start
Stop
Slow
Jog
When jogging with a variable frequency drive, the direction and _______________ of jogging can be controlled.
Force
Voltage
Speed
Distance
Depending on the drive, the inputs used to jog the motor may be _________________ than the inputs used for standard control.
The same
Common
Automated
Different
Common parameters associated with jogging include: jog _______________, Jog Accel, and Jog Decel.
Speed
Frequency
Outputs
Inputs
The _____________________ parameter established the deceleration rate for a motor when a job input is released.
Jog Acel
Braking
Jog Decel
Frequency
Which of the following is a difference between a vector drive and an inverter drive?
A vector drive includes feedback
Vector drives use more complex control logic
Vector drives provide more accurate control of motors
All of the answers are correct
None of the answers are correct
Most variable frequency AC drives will not allow you to use manual inputs to jog a motor
True
False
Which of the following is an advantage of starting a motor with an AC drive instead of line starting?
Inrush current can be controlled while maintaining starting torque
Motors can be operated above and below their rated speed
Reduced mechanical stress on machinery
All of the answers are correct
None of the answers are correct
Which of the following is not an advantage of using an AC drive instead of a DC drive?
Reduced maintenance costs because three-phase motors have a simpler construction
Lower initial cost because three-phase motors are less expensive than DC motors
An AC drive and motor can provide better starting torque than an equivalent DC drive and motor.
Lighter motors can be used (three-phase motors are lighter than DC motors of equivalent horsepower)
Which of the following is a common device that an AC drive can receive input from?
operator Station
Potentiometer
PLC
All of the answers
None of the answers are correct
Most variable frequency AC drives will allow you to control the direction and speed of jogging as well as how quickly the motor will stop when jogging is stopped
True
False
