Motors

Question 1

Define SPEED

Answer 1

The rate of rotation of a rotating body

Question 2

What are the units of speed?

Answer 2

Radians per second

Question 3

Why is torque-speed matching important?

Answer 3

It is important to match torque-speed characteristics to the load of the motor so it gets past initial static-friction phase of machine. This gets machine running and up to its running friction

Question 4

Draw a torque-speed curve for a FAN LOAD

Answer 4

Line gradually sloping upwards

Question 5

Draw a torque-speed curve for a HIGH STATIC FRICTION LOAD

Answer 5

Line slowly levels off and decreases

Question 6

Draw a torque-speed curve for a HIGH INERTIA LOAD

Answer 6

Straight line decreasing

Question 7

Draw a torque-speed curve for a COMPRESSOR load

Answer 7

Line curves downwards initially, before slowly bending upwards and extending into a straight line that increases

Question 8

Name an example of a FAN LOAD

Answer 8

Hairdryer

Question 9

Name an example of a HIGH STATIC FRICTION LOAD

Answer 9

Disc sander

Question 10

Name an example of a HIGH INERTIA LOAD

Answer 10

Steel rolling mill

Question 11

What are the consequences of incorrect torque-speed matching?

Answer 11

Low power output
Incorrect machine speed
Could fail to get past initial static friction