Unit 7 “Controlling the Process”

Question 1

The basic purpose of process control

Answer 1

to achieve the same desired results time after time

Question 2

The 3 things that an effective control system must continually do

Answer 2

sensing__________________________________________________________

3. _____comparing________________________________________________________
4. ______correcting___

Question 3

set point

Answer 3

desired value of the controlled variable

Question 4

deviation

Answer 4

difference between the measured variable and the set

point

Question 5

measured variable

Answer 5

characteristic you observe to determine the actual

status of a controlled variable

Question 6

disturbance

Answer 6

anything that upsets the process

Question 7

manipulated variable

Answer 7

what you adjust to keep the controlled variable at its

set point

Question 8

controlled variable

Answer 8

characteristic to be controlled in the process

Question 9

transmitter

Answer 9

converts and relays information between sensor and controller

Question 10

capacitance

Answer 10

the ability to store energy

Question 11

resistance

Answer 11

opposition to the transfer of energy

Question 12

final control element

Answer 12

takes action to adjust the manipulated variable

Question 13

recorder

Answer 13

keeps a continuous record of the value of the controlled variable

Question 14

sensor

Answer 14

collects information about measured variable_

Question 15

indicator

Answer 15

device that graphically shows at a glance the value of the controlled variable

Question 16

feedback control

Answer 16

process control

Question 17

interlock

Answer 17

are often feedback control loops that safeguard equipment and workers

Question 18

LIST 2 TIMES WHEN MANUAL CONTROL MAY BE USED IN AN AUTOMATED
PLANT

Answer 18

27. __ at start up, until process variable becomes stable enough for automatic controls __
28. __ for back up,_in case automatic instruments fail ________

Question 19

LIST 2 MISTAKES COMMONLY MADE BY A TECHNICIAN WHEN ADJUSTING
A PROCESS:

Answer 19

29. ___making more of an adjustment than is required____________________________
30. ___making a second adjustment before seeing the results of the first_

Question 20

proportional control

Answer 20

control element can be in any position within its

__operating range. Example: maintaining liquid level in a tank_

Question 21

two-positional control -

Answer 21

control element can be in only one of two positions, such as
on/off or open/closed. Examples: heating and air condition units, water heaters, ovens,
refrigerator compressors

Question 22

automatic control

Answer 22

instruments perform process control tasks. Instrument opens supply valve.

Question 23

manual control -

Answer 23

human performs some or all of the process control tasks. Operator opens supply valve.