Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

2nd Year Instrumentation > Control Instruments > Flashcards

Control Instruments Flashcards

1
Q

Def : feedback control

A

When an “error” ( difference between desired and actual value) occurs, the control system reacts to reduce the magnitude of the error by changing the manipated variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Def : feed forward control

A

Disturbances are measured 1st, calculations if any, then change the manipulated variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Closed loop difference from open loop

A

An open loop has no feedback , ie no self correction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Def : measured variable

A

A quantity , property or condition that is measured also called measurand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Def : setpoint (SP)

A

An input variable that sets the desired value of the controlled variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Def : process variable (PV)

A

Any variable property of a process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Def : error

A

Algebraic difference between the indication and ideal value of the measured signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Def : manipulated variable (MV)

A

The quantity or condition that is varied to correct error ie opening a valve more

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Def : controlled variable (CV)

A

In a contol loop the variable that is sensed so as to originate a feedback signal ie temp of the pipe after the ajax

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Def : transmitter

A

A transducer that senses a measured variable and converts that state to a standardized signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Def : controller

A

A device or program that operates automatically to regulate a controlled variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Def final control element (FCE)

A

The device that directly controls the manipulated variable. Ie the valve itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Def : disturbance

A

An undesirable change in a variable applied to a system which tends to adversely affect the value of the controlled variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

This indicates

A

Located in the feild
Visible at feild location
Normally operator accessible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

This indicates

A

Located on front of Central consol or main panel
Visible on front of panel / hmi
Normally operator accessible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

This indicates

A

Located in rear of Central consol or main panel
Not visible on front / hmi
Not normally accessible to operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

This indicates

A

Located on front of secondary or local panels
Visible on front of panel or hmi
Normally operator accessible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

This indicates

A

Located in rear of secondary or local panel
Located in feild cabinet
Not visible on front panel/ hmi
Not normally operator accessible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

This indicates

A

Instrument connection to process and equipment, impulse lines and analyzer sample lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

This indicates

A

Electrical or electronic signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

This indicates

A

Pneumatic signal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

This indicates

A

Communication link or bus connecting 2 or more independent microprocessor or computer based systems

23
Q

This indicates

A

Filled thermal element capillary tube, filled sensing line between pressure seal and instrument

24
Q

This indicates

A

Hydraulic signal

25
Q

A controller is direct acting if

A

Its output (CO) increases in response to an increasing measured signal (PV)

26
Q

This means ? DA or RA ?

A

Valve fails closed
DA

27
Q
A
28
Q

When a controller is in auto mode the operator only controller the

A

SP - set point

29
Q

Bumpless transfer is

A

A smooth transition from auto to manual and back

30
Q

A direct acting controller calculates error as ___ - ____

A

PV - SP

31
Q

A reverse acting controller calculates error as ____ - ____

A

SP - PV

32
Q

With an on/off controller
If the error is positive the CO is ___%
If the error is negative the CO is __%
If the error is 0 the CO :

A

+ = 100%
- = 0 %
0 = CO stays in last position

33
Q

A transmitter is almost always ____ acting

A

Direct

34
Q

____ = e (error) = sp - pv is for

A

Reverse acting

35
Q

_____ = e (error) = pv - sp is for

A

Direct acting

36
Q

This is? And works?

A

Forward hysteresis
It changes stat at PV and will not change back till below SP

37
Q

This is? And works?

A

Reverse hysteresis. The controller changes state at SP and doesn’t change again till below PV

38
Q

This is? And works?

A

Reverse hysteresis. The controller changes state at SP and doesn’t change again till below PV

39
Q

This is? And works?

A

Changes state at PV1 and doesn’t change again till below PV2. Both PV are equal from SP

40
Q

If SP is 40 degrees and PV is 30 degrees calculate pressure

A

Or (.8 degrees per kpg) +20 kpg

41
Q

If a tank has a set point of 3 meters ad is using a differential gap of 1.5m what is the UTP and LTP

A

UTP : 3.75
LTP : 2.25

42
Q

Explain how this works

A

When PV is below SP the relay R is closed sending the signal to the FCE. When the PV overcomes the SP it opens the nozzle and therefore the relay cutting off the signal to the FCE

43
Q

FCE stands for

A

Final control element

44
Q

Pid DA : sp __ co __ mv __ RA

A

DA : up down up
RA : down up down

45
Q

This is an _____ response

A

Underdamped

46
Q

This is an ______ response

A

Overdamped

47
Q

This is a _____ response

A

Critically damped response

48
Q

This is an _____ response

A

Marginally stable , aka sustained oscillatons

49
Q

This is a _____ response

A

Unstable response

50
Q
A
51
Q

This is

A

Pulse / response tho pulse

52
Q

What effect can proportional gain have

A

Smaller offset , but still takes as long to get to steady state

53
Q

A FC valve is ___ acting?
Why?

A

Direct
Increase in signal increases opening

54
Q

A FO valve is ___ acting?
Why?

A

RA
Increase in signal decreases opening

2nd Year Instrumentation (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions