Dersin Konusu: Endüstriyel Otomatik Kontrol Sistemlerinde Kullanılan Algılayıcılar, Dönüştürücüler ve Uygulamaları

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1 Endüstriyel Otomatik Kontrol Sistemleri Y.Doç.Dr. Tuncay UZUN, EHM Dersin Konusu: Endüstriyel Otomatik Kontrol Sistemlerinde Kullanılan Algılayıcılar, Dönüştürücüler ve Uygulamaları Dersin Amacı: Endüstriyel otomatik kontrol sistemlerinde kullanılan algılayıcılar ve dönüştürücülerin özellikleri, iç donanımı ve elektronik devrelerinin incelenmesi, uygulama devrelerinin analizi, incelenmesi ve tasarlanmasının öğretilmesidir.

2 2. Endüstriyel Otomatik Kontrol Sistemlerinde Kullanılan Algılayıcılar (sensors), Dönüştürücüler (transducers) ve Uygulamaları 2.1. Algılayıcı seçiminde kullanılan ölçütler Duyarlılık Doğrusallık Sınırlar Yanıt süresi Doğruluk Tekrarlanabilirlik Ayırıcılık Çıkışın tipi 2.2. Dönüştürücülerin fiziksel karakteristikleri Büyüklük ve ağırlık Güvenirlik Arabirim 2.3. Dönüştürücülerin gruplanması Temaslı dönüştürücüler Temassız dönüştürücüler

3 Temaslı dönüştürücüler Anahtarlar Piezoelektrik dönüştürücüler Konum ve yer değiştirmeyi algılama Potansiyometreler Doğrusal hareketli (Lineer, sürgülü) Dairesel hareketli (otary pot.) Doğrusal değişen farksal transformatör (LVDT) Mutlak optik kodlayıcı Artırmalı optik kodlayıcı Kuvvet algılama Moment (torque) algılama Uzaklık algılama (proximity sensor, yakın mesafe nesne algılama) Optik uzaklık algılayıcı Eddy akım algılayıcı Ultrasonik yankı Magnetik, Endüktif algılayıcılar Kapasitif algılayıcılar Temassız Dönüştürücüler 2.4. Endüstriyel Uygulamalar

4 SENSOS OVEVIEW Sensors: Convert a Signal or Stimulus (epresenting a Physical Property) into an Electrical Output Transducers: Convert One Type of Energy into Another The Terms are often Interchanged Active Sensors equire an External Source of Excitation: TDs, Strain-Gages Passive (Self-Generating) Sensors do not: Thermocouples, Photodiodes a 12.1

5 TYPICAL SENSOS AND THEI OUTPUTS POPETY SENSO ACTIVE/ Temperature Force / Pressure Thermocouple Silicon TD Thermistor Strain Gage Piezoelectric PASSIVE Passive Active Active Active Active Passive Voltage OUTPUT Voltage/Current esistance esistance esistance Voltage Acceleration Accelerometer Active Capacitance Position LVDT Active AC Voltage Light Intensity Photodiode Passive Current a 12.2

6 TYPICAL INDUSTIAL POCESS CONTOL LOOP EMOTE CONTOL OOM SIGNAL CONDITIONING 4 TO 20mA TANSMITTE 4 TO 20mA ECEIVE SIGNAL CONDITIONING TEMP SENSO ADC POCESS HOST COMPUTE MICO CONTOLLE HEATE DAC SIGNAL CONDITIONING 4 TO 20mA ECEIVE 4 TO 20mA TANSMITTE SIGNAL CONDITIONING a 12.3

7 STANDADIZATION AT THE DIGITAL INTEFACE USING SMAT SENSOS BANCH FIELD NETWOK NODE NODE DEVICE NETWOK NODE NODE SMAT SENSO SMAT SENSO SMAT SENSO SMAT SENSO SMAT SENSOS OFFE: Self-Calibration Linearization Interchangeability Standard Digital Interfaces a 12.4

8 BASIC ELEMENTS IN A "SMAT" SENSO Pressure Sensor, TD, Thermocouple, Strain Gage, etc. Precision Amplifier High esolution ADC Microcontroller Sensor a 12.5

9 ESISTANCE OF POPULA SENSOS Strain Gages Weigh-Scale Load Cells Pressure Sensors elative Humidity esistance Temperature Devices (TDs) Thermistors 120Ω, 350Ω, 3500Ω 350Ω Ω 350Ω Ω 100kΩ - 10MΩ 100Ω, 1000Ω 100Ω - 10MΩ a 2.1

10 MEASUING ESISTANCE INDIECTLY USING A CONSTANT CUENT SOUCE UT = I ( ) I a 2.2

11 THE WHEATSTONE BIDGE V B 4 3 = 1 V B V B = VB 1 2 AT BALANCE, IF 1 2 = 0 = 4 3 a 2.3

12 OUTPUT VOLTAGE AND LINEAITY EO FO CONSTANT VOLTAGE DIVE BIDGE CONFIGUATIONS V B V B V B V B : V B V B V B V B 2 2 Linearity 0.5%/% 0.5%/% 0 0 Error: (A) Single-Element Varying (B) Two-Element Varying (1) (C) Two-Element Varying (2) (D) All-Element Varying a 2.4

13 OUTPUT VOLTAGE AND LINEAITY EO FO CONSTANT CUENT DIVE BIDGE CONFIGUATIONS I B I B I B I B : I B 4 Linearity Error: 4 I B2 I B2 I B 0.25%/% (A) Single-Element Varying (B) Two-Element Varying (1) (C) Two-Element Varying (2) (D) All-Element Varying a 2.5

14 BIDGE CONSIDEATIONS Selecting Configuration (1, 2, 4 - Element Varying) Selection of Voltage or Current Excitation Stability of Excitation Voltage or Current Bridge Sensitivity: FS Output / Excitation Voltage 1mV / V to 10mV / V Typical Fullscale Bridge Outputs: 10mV - 100mV Typical Precision, Low Noise Amplification / Conditioning Techniques equired Linearization Techniques May Be equired emote Sensors Present Challenges a 2.6

15 USING A SINGLE OP AMP AS A BIDGE AMPLIFIE FO A SINGLE-ELEMENT VAYING BIDGE V B F V S F a 2.7 V S 2

16 USING AN INSTUMENTATION AMPLIFIE WITH A SINGLE-ELEMENT VAYING BIDGE V B V S UT = V B 4 2 GAIN G IN AMP EF UT -V S * * SEE TEXT EGADING SINGLE-SUPPLY OPEATION a 2.8

17 LINEAIZING A SINGLE-ELEMENT VAYING BIDGE METHOD 1 V B V S -V S VOUT = VB 2 a 2.9

18 LINEAIZING A SINGLE-ELEMENT VAYING BIDGE METHOD 2 V B V VB OUT = V S UT V S -V S 2 -V S 1 a 2.10

19 LINEAIZING A TWO-ELEMENT VAYING BIDGE METHOD 1 (CONSTANT VOLTAGE DIVE) V B V S -V S VOUT = VB a 2.11

20 LINEAIZING A TWO-ELEMENT VAYING BIDGE METHOD 2 (CONSTANT CUENT DIVE) V S UT = I B 2 GAIN I B G IN AMP EF UT V S -V S * SENSE I B * SEE TEXT EGADING SINGLE-SUPPLY OPEATION -V S * V EF a 2.12

21 EOS PODUCED BY WIING ESISTANCE FO EMOTE ESISTIVE BIDGE SENSO 350Ω 10V 350Ω 100 FEET, 30 GAGE COPPE WIE = 25 C TC = 0.385%/ C ASSUME 10 C TEMPEATUE CHANGE NUMBES IN ( ) 35 C 350Ω COMP 21Ω mV (5.44mV 28.83mV) LEAD 10.5Ω Ω (10.904Ω) LEAD 10.5Ω Ω (10.904Ω) STAIN GAGE 350Ω Ω 353.5Ω FS OFFSET EO OVE TEMPEATUE = 23%FS GAIN EO OVE TEMPEATUE = 0.26%FS a 2.13

22 3-WIE CONNECTION TO EMOTE BIDGE ELEMENT (SINGLE-ELEMENT VAYING) 350Ω 10V 350Ω 100 FEET, 30 GAGE COPPE WIE = 25 C TC = 0.385%/ C ASSUME 10 C TEMPEATUE CHANGE NUMBES IN ( ) 35 C - LEAD 10.5Ω Ω (10.904Ω) 350Ω mV ( mV) I = 0 STAIN GAGE 350Ω Ω 353.5Ω FS LEAD 10.5Ω Ω (10.904Ω) OFFSET EO OVE TEMPEATUE = 0%FS GAIN EO OVE TEMPEATUE = 0.08%FS a 2.14

23 KELVIN (4-WIE) SENSING MINIMIZES EOS DUE TO LEAD ESISTANCE FOCE V B 6-LEAD BIDGE SENSE LEAD SENSE FOCE LEAD a 2.15

24 CONSTANT CUENT EXCITATION MINIMIZES WIING ESISTANCE EOS I V EF 4-LEAD BIDGE LEAD I LEAD SENSE a 2.16 I = V EF SENSE I

25 DIVING EMOTE BIDGE USING KELVIN (4-WIE) SENSING AND ATIOMETIC CONNECTION TO ADC FOCE 5V 5V/3V LEAD AV DD DV DD 6-LEAD BIDGE SENSE SENSE V EF A IN A IN V EF AD7730 ADC 24 BITS FOCE LEAD GND a 2.17

26 TYPICAL SOUCES OF OFFSET VOLTAGE THEMOCOUPLE VOLTAGE 35µV/ C (T1 T2) V B T1 T2 I B I B S AMP COPPE TACES KOVA PINS a 2.18

27 AC EXCITATION MINIMIZES OFFSET EOS NOMAL DIVE VOLTAGES V B E OS = SUM OF ALL OFFSET EOS E OS V A = E OS - V A V B = ( E OS ) ( E OS ) = 2 EVESE DIVE VOLTAGES E OS V B = E OS V B a 2.19

28 SIMPLIFIED AC BIDGE DIVE CICUIT V B Q1 Q3 V 3,4 SENSE SENSE V 1,2 Q2 Q4 V B V 1,2 Q1,Q2 ON Q1,Q2 ON V 3,4 Q3,Q4 ON Q3,Q4 ON a 2.20