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Industrial Instruments 1Industrial Instruments 1Chapter 2Chapter 2
Analog Signal ConditioningAnalog Signal ConditioningDr. Bassam KahhalehDr. Bassam Kahhaleh
Princess Sumaya Univ.Princess Sumaya Univ.Electronic Engineering Dept.Electronic Engineering Dept.
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#nalog Signal $on itioning #nalog Signal $on itioning
ObjectiveOb
jectiveIntro uce the %asic techni&ue o' signalIntro uce the %asic techni&ue o' signalcon itioning in process control.con itioning in process control.
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#nalog Signal $on itioning #nalog Signal $on itioning
DefinitionDefinitionSignal con itioning re'ers to operationsSignal con itioning re'ers to operationsper'orme on signals to convert them to aper'orme on signals to convert them to a'orm suita%le 'or inter'ace (ith other'orm suita%le 'or inter'ace (ith otherelements in the process-control loop.elements in the process-control loop.
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#nalog Signal $on itioning #nalog Signal $on itioning
rinciples of Analog Signal Conditioningrinc
iples of Analog Signal ConditioningSignal-)evel an Bias $hangesSignal-)evel an Bias $hanges)ineari*ation)ineari*ation$onversions$onversions
$urrent Signal +4 , ! m#$urrent Signal +4 , ! m#Digital Inter'aceDigital Inter'ace
/iltering 0 Impe ance/iltering 0 Impe anceatchingatching
)oa ing)oa ing
!"
#"
!$ # %
Sensor "
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsDivi er $ircuitsDivi er $ircuits
)oa ing e''ect o' )oa ing e''ect o' ))
)) !!
# 1
# 2 # %
! S
! D
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsDivi er $ircuitsDivi er $ircuits
Sel'-heating +Sel'-heating + !! is a temperature sensoris a temperature sensor
ExampleExample6 S 7 2 6
1 7 1 K 8
4 K8 9 ! 9 1! K8 1.43 6 9 6 D 9 !.:3 6
.21 m; 9 P D 9 .5! m;
# 1
# 2
! S
! D
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits
;heatstone Bri ge;heatstone Bri ge
# 1 # 2
# 3
! D
# 4
V R R
RV
R R R
V 42
4
31
3
+−+=∆
3241 R R R R =
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits
;heatstone Bri ge;heatstone Bri ge=alvanometer Detector =alvanometer Detector
# 1 # 2
# 3
! D
# 4
! &h
# &h
a b
a
b
# '
'alvanometer
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits
;heatstone Bri ge;heatstone Bri ge)ea $ompensation)ea $ompensation
# 1 # 2
# 3
! D
# 4
a b
c
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits
;heatstone Bri ge;heatstone Bri ge$urrent Balance Bri ge$urrent Balance Bri ge
# 1 # 2
# 3
! D
# 4
ab
# (I
# 4 )) # (
*# 2+# 4, )) # (
5542
54
31
3 )( R I V
R R R R R
V R R
RV −++
+−+=∆
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsBri ge $ircuitsBri ge $ircuits
;heatstone Bri ge;heatstone Bri gePotential easurement Using Bri gesPotential easurement Using Bri ges
# 1 # 2
# 3
! D
# 4
ab
! c - ! " + ! a
042
4
31
3
=+−++ V R R R
V R R R
V xc
! "
0)(
5542
54
31
3 =−+++−+
+ R I V R R R
R RV
R R R
V x
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsRC RC /ilters/ilters
)o(-pass)o(-pass RC RC /ilters/ilters
)2/(1 C R f c π =
#
C ! out! in
2
1
1
+
=c
in
out
f f V
V
/
'ain
/ 0
1
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsRC RC /ilters/ilters
)o(-pass)o(-pass RC RC /ilters/ilters$asca e Stages$asca e Stages
# 1
C 1 ! out! in
/
'ain
/ 0
1
C 2
# 2
)2/(1 C R f c π =2
1
1
+
=c
in
out
f f V
V
%oading ffect # 2 )) # 1 C2 C 1
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#nalog Signal $on itioning #nalog Signal $on itioning
"ample 2 11"am ple 2 11 # measure signal has a 're&uency @ 1 KA* # measure signal has a 're&uency @ 1 KA*%ut there is un(ante noise at a%out 1 A*.%ut there is un(ante noise at a%out 1 A*.Design a lo(-pass 'ilter that attenuates theDesign a lo(-pass 'ilter that attenuates thenoise to 1C. ;hat is the e''ect on thenoise to 1C. ;hat is the e''ect on themeasurement signal at it ma . o' 1 KA*measurement signal at it ma . o' 1 KA*
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#nalog Signal $on itioning #nalog Signal $on itioning
"ample 2 11"am ple 2 116out " 6in 7 . 1 at 1 A*6out " 6in 7 . 1 at 1 A*
' ' cc 7 1 KA*7 1 KA*Use $ 7 .4:Use $ 7 .4: FF//
7 33.> 7 33.> 88 +too small - too much current+too small - too much currentUse $ 7 . 1Use $ 7 . 1 FF// 7 12>1 7 12>1 88Stan ar 7 1.2 KStan ar 7 1.2 K 88
' ' cc 7 1 51 A*7 1 51 A* 6out " 6in 7 . >>>>26out " 6in 7 . >>>>2 #t 1 KA*G #t 1 KA*G 6out " 6in 7 .>>56out " 6in 7 .>>5
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsRC RC /ilters/ilters
Aigh-passAigh-pass RC RC /ilters/ilters
)2/(1 C R f c π =#
C
! out! in
2
1
+
=
c
c
in
out
f f
f f
V V
/
'ain
/ 0
1
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#nalog Signal $on itioning #nalog Signal $on itioning
assive Circuitsassive CircuitsRC RC /ilters/ilters
Ban -passBan -pass RC RC /ilters/ilters
# 5
C 5
! out
# %
C%! in
/
'ain
/ 2
1
/ 1
If / 1 / 2 &hen $ou use the individual e6uations for the % 7 and 5 7
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersInverting #mpli'ier Inverting #mpli'ier
!out
# 1
! in
−
+
# 2
1
2
R R
V V
in
out −=
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational Amplifiers?on Inverting #mpli'ier ?on Inverting #mpli'ier
! out
# 1
! in
+
−
# 2
1
21
R R RV V inout
+=
! out - ! in
! in+
−
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersSumming #mpli'ier Summing #mpli'ier
!out
# 2
! 1
−
+
# 1
+−= 2
2
31
1
3V
R
RV
R
RV out
# 3
! 2
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersDi''erential #mpli'ier Di''erential #mpli'ier
!out
# 2
! 2
−
+
# 1
)( 211
2V V
R
RV out
−=
# 2
! 1# 1
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersDi''erential Instrumentation #mpli'ier Di''erential Instrumentation #mpli'ier
! out
# 3
! 2
−
+
# 2
)(2
1 211
21V V
R
R
R
RV
G
out −
+=
# 3
! 1
#2
−
+
+
−
# 1
# 1
# '
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational Amplifiers6oltage-to-$urrent $onverter 6oltage-to-$urrent $onverter
IL
# 3
−
+
#1
in L V R R
R I
31
2−=
#2! in
# 4
# (
# %
42531 )( R R R R R =+
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational Amplifiers$urrent-to-6oltage $onverter $urrent-to-6oltage $onverter
I−
+
#
#
! out IRV out −=
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersIntegrator Integrator
! out
#
! in
−
+
C∫ −= dt V RC V inout 1
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersDi''erentiator Di''erentiator
! out
#
! in
−
+
C
dt dV
RC V in
out −=
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersPo(er SupplyPo(er Supply
! out
! in−
+
! CC
! CCt0
+! CC
− ! CC
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersPo(er SupplyPo(er Supply
! out
! in−
+! CC
t
+! CC
0
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#nalog Signal $on itioning #nalog Signal $on itioning
Operational AmplifiersOperational AmplifiersPo(er SupplyPo(er Supply
! out!CC
t
+! CC
0
! in
−
+
8 ! CC
8 ! CCH
−
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nd of Chapter 2nd of Chapter 2
#nalog Signal $on itioning #nalog Signal $on itioning