Lecture 3, Process

Question 1

What is a process?

Answer 1

it is defined as the chnaging or refining of raw materiales that pass through or remain in different states to create end products

Question 2

what is a single-variable processes?

Answer 2

one vriable is be controlled

Question 3

what is a multi-variable processes?

Answer 3

which many vriables perhaps interrelated, may require regulation

Question 4

What is process control?

Answer 4

it refers to the methods that are used to control process variables when manufacturing a prodcut

Question 5

What are the main reasons for process control?

Answer 5

to reduce product variability
increase efficiency
Ensure process safety

Question 6

what are the three tasks of control loops?

Answer 6

Measurement, comparison and Adjustment

Question 7

what is a process variable?

Answer 7

it is a condition of the processed material that can change the manufacturing process in some way

Question 8

What is a setpoint?

Answer 8

is a value for process variables that is desired to be maintained, no fluctuation value needed

Question 9

Draw a control loop

Answer 9

Do you know how to do it?

Question 10

how do we control vriables in a process?

Answer 10

by measuring the variable

Question 11

what is a measurement?

Answer 11

it refers to the conversion of the variable into some corresponding analogue signal of the vairale (electrical voltage)

Question 12

what is a sensor?

Answer 12

a device that perofrms the initial measurement (energy conversion into a electrical information)

Question 13

what is a transducer?

Answer 13

a device that converts any signal from one form to another

Question 14

ae al sensors transducers?

Answer 14

yes, but not all transducers are sensors

Question 15

what is an Error?

Answer 15

it is the difference between the measured variable and the setpoint.

Question 16

what is the objective of any control scheme?

Answer 16

it is to minimized or eliminate error

Question 17

what are the three major components of an error?

Answer 17

Error magnitude
Duration of error
Rate of change of error

Question 18

Error magnitude is?

Answer 18

the deviation between the values of the setpoint and the porcess variable

Question 19

Duration of error is?

Answer 19

the length of time that an error condition has existed

Question 20

Rate of change of error

Answer 20

the error magnitude at any point in time compared to the previous error. This procides the basis for determining the change in error

Question 21

what is an Error detector?

Answer 21

a device that determines if the process variable is above or below the desired setpoint

Question 22

what happedn if the PV is above or brrlow the setpoint?

Answer 22

an error singal proportional to the error is generated

Question 23

what is an error signal used for?

Answer 23

it is used by the controller to generate a control action

Question 24

what is often a part of the controller device?

Answer 24

error detector

Question 25

what is a controller?

Answer 25

a device that acts on the error signal generated to determine what control action should be taken

Question 26

what is an evaluation of the process

Answer 26

it consists of determining action required to bring the controlled variable to the setpoint value

Question 27

What are control element?

Answer 27

a device that provides the required chnages in the controlled variable to bring it to the setpoint

Question 28

what does it accept?

Answer 28

an input from the controller, which is then transformed into some proportional operation performed on the process

Question 29

What are Manipulated vairable?

Answer 29

this are varaible which can be manipulated in order to have control over the process vairable, also call control variable

Question 30

draw the relationship between the setpoint, measured vairable and controller?

Answer 30

do you know it?

Question 31

what are the componten of a process control loop?

Answer 31

error detector, controller and final control element

Question 32

what is an open loop?

Answer 32

no feedback from the process

Question 33

what is the main difference between an open and a feedback loop?

Answer 33

in an open loop, the control action does not depend on changes in the process variable. Rather the control action is based on changes in the input to the porcess

Question 34

how does the signal flow?

Answer 34

its form a complete circuit from the process through measurement, error dector, controller and final control element

Question 35

why do we called the process control loop also a feedback loop?

Answer 35

because one determine an error and feed back a correction to the porcess

Question 36

draw an open, feed forward and feed backward loop

Answer 36

hope you know it

Question 37

What is the most important ccontroller?

Answer 37

Proportional-integral-derivative controller (PID)

Question 38

how does a PId works?

Answer 38

it continuously caculates an error value as difference between the setpoint and a measured process variable. its then apply a correction based on proportional, integral and derivative terms

Question 39

what does proportional in the PID controller means?

Answer 39

the magnitude of the deviation, how far is the current value far from the actual value (SP-PV), describing the current value

Question 40

what does integration in the PID controller means?

Answer 40

is the duration over time, it decrease if the error is eliminated (SP-PV), past values

Question 41

what does derivative in the PID controller means?

Answer 41

slop, rate of change, estimation of the future trend (SP-PV)

Question 42

What is a process capability?

Answer 42

the ability of a process to meet the design specification

Question 43

what is the eqaution for the c(P)

Answer 43

USL-LSL/6sigma

Question 44

when is c(P) valid?

Answer 44

if real mean is equal to the nominal value

Question 45

when is the process capable?

Answer 45

when c(P) is greater than 1

Question 46

when can c(P) be used?

Answer 46

by measuring of variation only

Question 47

what is the better value to describe the process capability?

Answer 47

process capability index

Question 48

What is the process capability index equation?

Answer 48

c(PK)= min(USL-mean/3 sigma); )mean-LSL/3sigma)

Question 49

when can c(Pk) is a?

Answer 49

measnue of location and variation