MODULE 1: Introduction To Process Control

Question 1

Accomplished by observing a parameter, comparing it to some desired value, and initiating a control action to bring the parameter as close as possible to the desired value.

Answer 1

Process control

Question 2

Three main factors or terms of process systems:

Answer 2

• Manipulated variables • Disturbances variables • Controlled variables

Question 3

Diagram for the three main factors of process control:

Answer 3

Manipulated variables -> PROCESS -> Controlled variable
^
|

                                      Disturbances

Question 4

Is the input variable or parameter to a process that is varied by a control signal from the processor to an actuator.
By changing the input variable the value of the measured variable can be controlled.

Answer 4

MANIPULATED VARIABLE

Question 5

Typical manipulated variables

Answer 5

• valve position
• motor speed
• damper position
• blade pitch

Question 6

Monitored output variable from a process. The value of monitored output parameter is normally held within tight given limits.

Answer 6

CONTROLLED/MEASURED VARIABLE

Question 7

Controlled variables conditions are:

Answer 7

• temperature
• level
• position
• pressure
• pH
• density
• moisture content
• weight
• speed

Question 8

The controlled variables are those conditions that must be

Answer 8

Maintained at some desired value

Question 9

Enter or affect the process and tend to drive the controlled variables away from their desired value or set point condition.

Answer 9

DISTURBANCES

Question 10

Typical disturbances are

Answer 10

• changes in ambient temperature

* in demand for product or in the supply of feed material

Question 11

Four elements of process control systems are:

Answer 11

• process
• measurement
• evaluation
• control

Question 12

Consist of an assembly of equipment and material that is related to some manufacturing operation or sequence

Answer 12

Process

Question 13

Refers to the conversion of process variable into an analog or digital signal that can be used by the control system. The device that performs the initial measurement is called a sensor or instrument

Answer 13

Measurement

Question 14

The _________ in a control loop is the device that exerts a direct influence on the process or manufacturing sequence.

Answer 14

Control element

Question 15

What are the devices used as control elements

Answer 15

Electrical motors, pumps, dampers and control valves

Question 16

Early humans found it necessary to regulate some of their external environmental parameters to maintain life. This regulation could be defined as _______.

Answer 16

Artificial process control or Process control