Mech 4 Exam UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS
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 above
None of the above - CORRECT ANSWER All of the above
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 above
None of the above - CORRECT ANSWER All of the above
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 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). - CORRECT ANSWER An AC drive and motor can provide better
starting torque than an equivalent DC drive and motor.
Most variable frequency AC drives will not allow you to use manual inputs to jog a motor.
T/F - CORRECT ANSWER False
Which of the following is a common device that an AC drive can receive input from?
Operator station
potentiometer
PLC
All of the above
None of the above - CORRECT ANSWER All of the above
Many variable frequency AC drives provide low speed boost to increase the voltage at low
frequencies.
True
False - CORRECT ANSWER True
What should the maximum frequency setting be for a 2-pole motor with a 60 Hz rating?
120 Hz
75 Hz
60 Hz
150 Hz - CORRECT ANSWER 75 Hz
Most variable frequency drives do not allow you skip frequencies that put stress on a motor.
True
False - CORRECT ANSWER False
AND CORRECT ANSWERS
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 above
None of the above - CORRECT ANSWER All of the above
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 above
None of the above - CORRECT ANSWER All of the above
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 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). - CORRECT ANSWER An AC drive and motor can provide better
starting torque than an equivalent DC drive and motor.
Most variable frequency AC drives will not allow you to use manual inputs to jog a motor.
T/F - CORRECT ANSWER False
Which of the following is a common device that an AC drive can receive input from?
Operator station
potentiometer
PLC
All of the above
None of the above - CORRECT ANSWER All of the above
Many variable frequency AC drives provide low speed boost to increase the voltage at low
frequencies.
True
False - CORRECT ANSWER True
What should the maximum frequency setting be for a 2-pole motor with a 60 Hz rating?
120 Hz
75 Hz
60 Hz
150 Hz - CORRECT ANSWER 75 Hz
Most variable frequency drives do not allow you skip frequencies that put stress on a motor.
True
False - CORRECT ANSWER False
