Lecture 7

Question 1

What is automation?

Answer 1

Transforming a mechanism, device, machine, facility or process to make it automatic.

Question 2

What is the goal of a programmable logic controller (PLC)?

Answer 2

Bring added value to a set of raw materials to produce products of higher value.

Question 3

What human intervention do PLC’s need (4)?

Answer 3

• machine monitoring
• loading, unloading and inspecting machines
• participation in the production process
• adjustment and maintenance

Question 4

What do PLC’s gain from automation(4)?

Answer 4

• reduced labor cost and material savings
• reducing hazardous work and safety increase
• improved product quality and performance
• higher productivity and quality job creation

Question 5

What is hardware?

Answer 5

Implementing physical decides to achieve the desired logic/operation.

Question 6

What is a pro and con of hardware?

Answer 6

Pro: reliability
Con: non flexible for future changes

Question 7

What is software?

Answer 7

Using programming to achieve desired logic /operation.

Question 8

What is a pro and con of software?

Answer 8

pro: flexible to future changing
con: not used for important safety functions

Question 9

What is the single proven technology protection method(3)?

Answer 9

• position switched or forced open contacts
• manually check for periodic safety functions.
• oversizing some components

Question 10

What is the single with supervision protection method(2)?

Answer 10

• similar to single proven technology protection, but also has self monitoring features.
• failure detecting circuits made with contactors and relays

Question 11

What is the redundant protection method(4)?

Answer 11

• duplicating critical components or functions
• using different technologies
• combining the normally open and normally closed contact interlocks
• combining different, electrical and non-electrical systems.

Question 12

What is the redundant with supervision protection method(1)?

Answer 12

same as the redundant protection method but adds a continuous supervision function

Question 13

What is ladder logic?

Answer 13

was used before PLC’s to describe automation technology made by using electromagnetic relays

Question 14

What is the difference between a static and dynamic system?

Answer 14

static systems do not change with time while dynamic systems do change with time.

Question 15

What makes a good model(6)?

Answer 15

• clearly defined questions
• clearly stated assumptions
• adaptable
• reproducible( clearly defined variables)
• use the best data available
• interpret results with caution

Question 16

What are the 6 steps of the design approach?

Answer 16

1. define the system and its components
2. make a mathematical model with its assumptions
3. make differential equations describing the model
4. solve equations for desired output variables
5. examine solutions and assumptions.
6. if needed, reanalyze or redesign the system

Question 17

What is a control system?

Answer 17

an interconnection of components forming a system that will provide a desired system response.

Question 18

What is the difference between an open and closed loop control system?

Answer 18

Closed-loop: uses a measurement of the output signal and a comparison with the desired output to generate an error signal that is used by the controller to adjust the actuator.

Open-loop: directly generates the output in response to an input signal.

Question 19

What are the advantages of closed-loop feedback control systems(5)?

Answer 19

• decreased sensitivity of variations in parameters
• rejects disturbances
• attenuate the measurement noise
• reduce the steady-state error
• easy control and adjustment of the transient response of the system.

Question 20

What is a linear system?

Answer 20

A system that satisfies the properties of superposition and homogeneity.

Question 21

What are the superposition principle?

Answer 21

for all linear systems, the net response caused by two or more stimuli is the sum of the response that would have been caused by each stimulus individually.

Question 22

What is the homogeneity principle?

Answer 22

the output of a linear system is always directly proportional to the input, so if we put in twice as much into the system we should get twice as much back,

Question 23

What is linear approximation?

Answer 23

is as accurate as the assumption of small signals is applicable to a specific problem.

Question 24

What are the 3 test input signals?

Answer 24

1. step input
2. ramp input (integral of the step input)
3. parabolic input (integral of the ramp input)

Question 25

What is a performance index?

Answer 25

a quantitative measure of the performance of a system and is chosen so that emphasis is given to the import system specifications.

Question 26

What is the purpose of the ISE?

Answer 26

used to penalize excessively over / underdamped systems, its minimum value occurs for a compromise value of the damping.