Thuyet Trinh 1.ppt

8/10/2019 Thuyet Trinh 1.ppt

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I.Khi nimII.Phn loiIII.Cu to v nguyn l hot ng

IV.ng dngV.Mch ng dng


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I. Khi nim:

Cm bin l thit b dng o, m,cm nhn,cc i lng vt l khng

in thnh cc tn hiu inNhit l mt i lng khng lin quan

n in

V vy cm bin nhit l cm binchuyn i tn hiu nhit sang tn hiuin


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II. Phn loi: in tr kim loi ( RTD-resitance temperature detector ). in tr oxit kim loi (Thermistor ) Cm binnhitbn dn( Diode, IC ,.). Cp nhit in ( Thermocouple ).


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III. Cu to v nguyn l hot ngA. Nhit in tr kim loi

(RTD-Resitance Temperature Detector) Cuto: gmmtdy dnbngkim loinh: platin, niken, ng

qun trn mtli cch in.

Nguyn l hotng:Nhittngth intrtng.

21

3

1 2

3

21

3

1. V 2. Dy in tr 3.Li cch in


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u im: o chnh xc cao, d s dng, chiu di khnggii hn

Khuyt im: di o b, gi thnh cao Di o: -200700 oC

ng dng: Ngnh cng nghip chung, Cng nghip mitrng ....


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Nhit in tr kim loi


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Cuto: Thermistor cchtotcc oxid bn dnahnh thnh: MgO, MgAl2O4, Mn2O3, Fe3O4, NiO, ZnTiO4didngbtvctrnlntheo mttlnhtnh. Sau khi trnvinhau, ngitanen hnhpthnhphinv nung nhit1000C. Trnbmtca

phinsau khi nung, ngita hn cc dy nivphlnphinmtlpkim loi.

Nguyn l: Thay i in tr khinhit thay i.

Bin tr oxit kim loi (Thermistor)


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- u im: Bn, r tin, d ch to.- Khuyt im: Dy tuyn tnh hp.- Thng dng: Lm cc chc nng bo v, p vo cun dyng c, mch in t.- Tm o: 50


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Trong h thng hot ng ca xe t hin i

;


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NTC trong t lnh


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Cu tao:Da trn tnh cht ca cccht bn dn Diode,transistor

Nguyn l hot ng: s phn ccca cc cht bn dn b nh hng

bi nhit .

u im: R tin, d ch to, nhy cao, chng nhiu tt, mchx l n gin.

- Khuyt im: Khng chu nhit cao, km bn.

- Thng dng: o nhit khngkh, dng trong cc thit b o, bov cc mch in t.

- Tm o: -50


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Mt s linh kin cm bin nhit

Cm bin LM35l b cm bin nhit mch tchhp chnh xc cao m in p u ra ca n t ltuyn tnh vi nhit theo thang Celsiusc im chnh ca cm bin LM35+ in p u vo t 4V n 30V+ phn gii in p u ra l 10mV/oC+ chnh xc cao 25 C l 0.5 C+ Tr khng u ra thp 0.1 cho 1mA tiDi nhit o c ca LM35 l t -55 C -150 C vi cc mc in p ra khc nhau.Xt mt s mc in p sau :- Nhit -55 C in p u ra -550mV- Nhit 25 C in p u ra 250mV- Nhit 150 C in p u ra 1500mVTy theo cch mc ca LM35 ta o cc giinhit ph hp. i vi h thng ny th o

t 0 n 150.
http://codientu.org/tags/c%E1%BA%A3m+bi%E1%BA%BFn+lm35/http://codientu.org/tags/c%E1%BA%A3m+bi%E1%BA%BFn+lm35/


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DS18B20


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Cuto: gm2 kim loikhc nhau chn chung vihau mtu

gil unng, 2 ucn likhng hn chung gil ulnhhayuchun.

D. Cp nhit in (Thermocouple )


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Nguyn l hot ng: da trn hiu ng Seebeck, khi c s chnh lcnhit gia u nng v u lnh ca cp nhit th u ra(u lnh)s xut hin sut in ng E.

u im: Bn, o nhit cao. Khuyt im:Nhiu yu t nh hng lm sai s. nhy khng cao. Thng dng: L nhit, mi trng kht nghit, o nhit nht my

nn, Tm o: -100 D.C


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Cp nhit in


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Cm bin nhit c gn a gia nhit


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V. Mch ng dng

Mch o s dng cm bin nhit in tr kim loi: chuyn sthay i in tr ca cm bin theo nhit thnh s thay i inp, ta kt ni cm bin vi mch o nh sau:

= 10v Dc

R1,3,6=5k

R,R4,2=10k


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Mch o dng vi mch bn dn:


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Mch cnh bo nhit cho thit b
http://2.bp.blogspot.com/-i2h9-6fXyyw/UIAI_RtkcWI/AAAAAAAADmE/OZHRQiEOx_o/s1600/Mach+canh+bao+nhiet+do+DINHBAS+Blog.gifhttp://2.bp.blogspot.com/-i2h9-6fXyyw/UIAI_RtkcWI/AAAAAAAADmE/OZHRQiEOx_o/s1600/Mach+canh+bao+nhiet+do+DINHBAS+Blog.gifhttp://2.bp.blogspot.com/-i2h9-6fXyyw/UIAI_RtkcWI/AAAAAAAADmE/OZHRQiEOx_o/s1600/Mach+canh+bao+nhiet+do+DINHBAS+Blog.gif


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Mch cnh bo nhit dng Thermistor:


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Cu Diode

R-le iu kin

Nhit in tr


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Cm bin nhit c lp trong cc my p trng o vduy tr nhit n nh:


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Dng iu chnh t ng tc quay ca qut theo nhit :


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Cm bin nhit c lp trn cnh tn nhit ca mt sb ngun

v mts thit b trong mch in t o v iu khin cnh bonhit:


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