# Control Engineering Safety Integration Webcast Learning Unit Exam

## April 14, 2011

This webcast is free and 1 learning unit/0.1 CEU will be provided upon successful completion of an exam following the webcast.

You must get 8 of 10 questions correct to pass the exam. You may retake the exam if necessary. You will be notified whether you passed or failed automatically after taking the exam. Upon passing the exam, a hardcopy certificate will be mailed within 30 days to you at the address you provide below.

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Question 1 *

What is the other common name for induction motors?

Asynchronous motors
Synchronous motors
Permanent magnet motors
Wound field motors
Brush type dc motors
Question 2 *

The underlying objective of all motors is to:

Produce torque (rotating moment)
Produce speed (rotating shaft)
Produce speed at required torque (produce power)
Convert electrical energy into mechanical energy
All of the above
Question 3 *

Calculation of Power in Watts:

Speed/Torque = Power in Watts
Torque-Speed = Power in Watts
RPM x Lb-in (torque) = Watts
Radians/Sec (speed) x Newton-Meters (torque) = Power (Watts)
RPM x oz-in (torque) = Power (Watts)
Question 4 *

Differences between PM servomotor and induction servomotor:

A servomotor always has a feedback element
A PM servomotor has permanent magnets in the rotor
An induction servomotor has a squirrel cage induction rotor
The stators of an induction servomotor and a permanent motor are quite similar
All of the above
Question 5 *

Speed-torque characteristics:

PM servomotors have linear (easier to control) speed-torque characteristics
Induction servomotors have non-linear (harder to control) speed-torque characteristics
PM servomotors generally have higher starting torque when compared to induction servomotors of similar power ratings
The starting torque of induction servomotors can be increased by change in rotor design
All of the above
Question 6 *

PM servo motors are neither smaller nor lighter than induction servomotors
PM servo motors are less readily available than induction servomotors in smaller power ratings (less than 10 kW)
Induction servomotors are not available in higher horse power levels (greater than 100 hp)
All of the above
None of the above
Question 7 *

Applications of PM servos and induction servos:

A. PM servos are never used in machine tool axis drive applications
B. Inductions servos are never used in large process applications
C. PM servos are never used in packaging machinery
D. All of the above statements are true
E. Answers a, b, and c are false
Question 8 *

PM servo motor versus induction servo motor cost difference:

PM servo motor rotors may cost as much as 20% more than induction servomotor rotors in 10 kW power ratings
As the power increases, the cost difference between PM servomotors and induction servomotors decreases exponentially
The stators of induction servomotors and PM servomotors are completely different from each other with respect to cost
The main cost difference between an induction servomotor and a PM motor is in the stator
The main cost difference between an induction servomotor and a PM servomotor is in the shaft
Question 9 *

PM servos versus induction servos: which statement is true?

For applications less than 10 kW, an induction servo is the first choice, AND for applications greater than 150 kW, a PM servo is the first choice
For application less than 10 kW, a PM servo is the first choice AND for applications greater than 150 kW, an induction servo is the first choice
Neither is true
Both are true
Question 10 *

Which of the following statements is true:

PM servos are readily available in low (< 10 kW) power ratings
Induction servos are generally not available in low (> 10 kW) ratings
PM servos are preferable in rapid start-stop applications because they have lower inertia
If the application is for a 200 hp process control application, the only choice may be to use an induction servo
All of the above