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CONTROL SYSTEM

INSTRUMENTATIOArellano, Hanna Lissajous L.

Cruz, Tifany Grae !.

Ila"a, Marie Luz #.

Ma$eo, Mizzra% M. Tan, Rose Marie &.

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SENSORS, TRANSMITTERS, AN' TRANS'UCERS T%e o(era$ion o) o*(le+ inus$rial (lan$s -oul e i/ul$, i) no$ i*(ossi-i$%ou$ $%e *easure*en$ an on$rol o) ri$ial (roess 0ariales. Lar"e ($y(ially %a0e %unres or $%ousans o) (roess 0ariales $%a$ are re(e$i$i0*easure on1line e0ery )e- seons or *inu$es.

A (%ysial 0ariale is *easure y a sensor -%i% (roues a (%ysial res(

2e."., ele$rial or *e%anial3 $%a$ is rela$e $o $%e 0alue o) $%e (roess 0a

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4or e+a*(le, in $%e s$irre1$sys$e* in 4i". 6.7, $%e $%er*"enera$es a *illi0ol$ ele$riinreases as $%e $e*(era$ur

inreases. Ho-e0er, )or $%is*easure*en$ $o e use in alula$ions, $%e *illi0ol$ le0*us$ e on0er$e $o an a(0ol$a"e or urren$ si"nal in ain(u$ ran"e )or $%e on$rolleon0ersion is one y a tran

I$ is o)$en neessary $o on0ins$ru*en$a$ion si"nal )ro*ano$%er. A e0ie $%a$ (er)oon0ersion is re)erre $o as

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S$anar Ins$ru*en$a$ion Si"nalLe0els&e)ore 769:, ins$ru*en$a$ion in $%e (roess inus$ries u$ilize (neu*a$i 2(ressure3 si"nals $o $rans*i$ *easure*en$ an on$rol in)or*a$ion al*os$e+lusi0ely. T%ese e0ies *a5e use o) *e%anial )ore alane ele*en$s"enera$e si"nals in $%e ran"e o) ; $o 7< (si", an inus$ry s$anar. Sine aele$roni ins$ru*en$a$ion %as eo*e (reo*inan$. T%e s$anar si"nal ranalo" ins$ru*en$s are = $o >: rnA an 7 $o < !, ire$ urren$ 2!'C3.

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Sensors ? Sele$ion Cri$eria

7. Measure*en$ ran"e 2s(an3. T%e re8uire *easure*en$ ran"e )or $%e (ro0ariale *us$ lie en$irely -i$%in $%e ins$ru*en$@s ran"e o) (er)or*ane.

>. er)or*ane. 'e(enin" on $%e a((lia$ion, auray, re(ea$aili$y, or s*easure o) (er)or*ane is a((ro(ria$e. 4or lose1loo( on$rol, s(ee o) realso i*(or$an$.

;. Reliaili$y. Manu)a$urers (ro0ie aseline oni$ions. re0ious e+(erien

*easure*en$ e0ie is 0ery i*(or$an$.=. Ma$erials o) ons$ru$ion. T%e ins$ru*en$ *ay nee $o -i$%s$an %i"%

$e*(era$ures, %i"% (ressures, an orrosi0e an arasi0e en0iron*en$s. 4oa((lia$ions, seals or (ur"es *ay e neessary.

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Sensors ? Sele$ion Cri$eria 2Co$B

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Temperature. T%e *os$ o**on $e*(era$uresensors are lle sys$e*s, $%er*oou(les,resis$ane $e*(era$ure e$e$ors 2RT's3, an(yro*e$ers.

Diferential Pressure. 4or (neu*a$iins$ru*en$a$ion, (ressure sensin" is 8ui$es$rai"%$)or-ar. A ello-s, ouron $ue, oria(%ra"* isola$es (roess li8ui or "as )ro* $%eins$ru*en$, a$ $%e sa*e $i*e )urnis%in" a eDe$ion$o a )ore1alane ele*en$ $%a$ "enera$es a(ro(or$ional si"nal in $%e ; $o 7< (si" ran"e.

Liquid or Gas Flow Rate. Sele$ion o) a Do-$rans*i$$er s%oul onsier $%e )ollo-in" )a$orsna$ure o) $%e Do-in" *a$erial 2li8ui"assoli3,orrosi0eness, *ass 0s. 0olu*e *easure*en$,na$ure o) $%e si"nal, os$, auray, urren$ (lan$(ra$ie, s(ae a0ailale, an neessary*ain$enane 2S(i$zer, >::73.

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Liquid Level. T%e (osi$ion o) a )ree Doa$ or $%e uoyany efe$s on a +e De$e$e an on0er$e $o le0el i) $%e li8ui ensi$y is 5no-n. T%e iferene ie$-een $%e 0a(or ao0e $%e li8ui an $%e o$$o* o) $%e li8ui an e si*ila

Chemical Composition. C%e*ial o*(osi$ion is "enerally $%e *os$ %allen"*easure*en$. &e)ore $%e era o) on1line analyzers, *essen"ers -ere re8uire sa*(les $o $%e laora$ory )or analysis an $o re$urn $%e resul$s $o $%e on$rol r

In orer $o o$ain 8uan$i$a$i0e o*(osi$ion *easure*en$s, s(ei ins$ru*en

%osen e(enin" on $%e na$ure o) $%e s(eies $o e analyze. Measurin" a s(onen$ra$ion re8uires a uni8ue %e*ial or (%ysial a$$riu$e.

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As an e+a*(le, o*(le$e analysis o) a o*us$ion "as re8uires *ul$i(le onanalyzers as )ollo-s

Physical Properties. T%is a$e"ory inlues su% *easure*en$s as ens*ois$ure, $urii$y, 0isosi$y, re)ra$i0e ine+, (H, iele$ri ons$an$, an onu$i0i$y.

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S$a$i an 'yna*i C%ara$eris$i• As no$e ao0e, $%e ou$(u$ si"nal )ro* a

sensor $rans*i$$er 2or $rans*i$$er3 *us$ eo*(a$ile -i$% $%e in(u$ ran"e o) $%eon$roller $%a$ reei0es $%e si"nal. Trans*i$$ersare "enerally esi"ne $o e direct-acting; $%a$is, $%e ou$(u$ si"nal inreases as $%e *easure0ariale inreases. In ai$ion, *os$o**erial $rans*i$$ers %a0e an ajus$alein(u$ ran"e. 4or e+a*(le, a $e*(era$ure$rans*i$$er *i"%$ e ajus$e so $%a$ $%e in(u$

ran"e o) a (la$inu* resis$ane ele*en$ 2$%esensor3is

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4or any linearins$ru*en$,

4or a nonlinear ins$ru*en$, $%e "ain a$ an o(era$in" (oin$ is $%e $an"en$ $o $%ara$eris$i in(u$1ou$(u$ rela$ion a$ $%e o(era$in" (oin$. 4i"ure 6.9 illus$raase. No$e $%a$ $%e "ain %an"es -%ene0er $%e o(era$in" (oin$ %an"esJ %e(re)erale $o u$ilize ins$ru*en$s $%a$ e+%ii$ nearly linear e%a0ior. Gain Km-%en $%e s(an is %an"e u$ is in0arian$ $o %an"es in $%e zero.

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Dynamic Characteristics oSensor-TransmittersMany sensor1$rans*i$$ers res(on 8ui5ly an %a0e *easure*en$ yna*ine"li"ile o*(are $o slo-er (roess yna*is. 4or o$%er a((lia$ions -%*easure*en$ yna*is are no$ ne"li"ile, si"nian$ yna*i errors an ois, lar"e iferenes e$-een $%e $rue 0alues an $%e *easure 0alues )or $oni$ions. 4or e+a*(le, a are $%er*oou(le -ill %a0e a ra(i res(onse $o%an"in" Dui $e*(era$ure. &u$ a $%er*oou(le (lae in a (ro$e$i0e $%e-i$% a lar"e *ass an lar"e s(ei %ea$, an %a0e a si"nian$ *easure*

ons$an$. Re(resen$a$i0e $i*e ons$an$s )or a 0arie$y o) sensors %a0e een2Ri""s an Kari*, >::93.

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Many sensor1$rans*i$$ers %a0e o0er a*(e yna*is an e+%ii$ *ono$onires(onses $o a s$e( %an"e in $%e 0ariale ein" *easure. T%us, i$ is reasona*oel $%is $y(e o) *easure*en$ yna*is as a rs$ orer $rans)er )un$ion e$%e a$ual 0alue y an $%e *easure 0alue Ym:

Si"nian$ *easure*en$ yna*is an our ue $o a (oor sensor loa$ion or a lsa*(lin" line. 4or e+a*(le, i) a (H sensor )or a on$inuous neu$raliza$ion (roessloa$e in $%e e+i$ line, a lon" is$ane )ro* $%e (roess 0essel, a si"nian$ $i*ean arise ue $o $%e is$ane10eloi$y la". Ti*e elays an also resul$ -%en an ono*(osi$ion *easure*en$ re8uires a lon" sa*(le line eause an e+(ensi0e ana(ro$e$e en0iron*en$ is loa$e a lon" is$ane )ro* $%e sa*(le loa$ion near $(roess uni$. T%is o**on si$ua$ion an (roue a si"nian$ is$ane10eloi$y la