Resistance and-temperature-sensors-applications

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Learn what sensors are and what do they do, applications using Acromag's amplifier, measurement techniques.

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Resistance and-temperature-sensors-applications

  1. 1. Resistance/Temperature Sensors & Applications By: Donald Lupo 390765 S Wixom Road, PO Box 437 Wixom, MI 48393-7037 USA www.acromag.com P 248-624-1541 F 248-624-9234 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  2. 2. Agenda • Discuss Three Sensor Types ◦ Potentiometers/Slidewires ◦ Thermistors ◦ Resistance Temperature Detectors (RTD’s) • • • • Applications Construction Measurement Technique Acromag Amplifier Interface Solutions www.acromag.com www.acromag.com 248-624-1541 248-6241541
  3. 3. Potentiometer/Slidewire Sensors • What Are They? ◦ Variable Resistance Sensors ◦ 3-Wire Terminal Resistor ▪ Two Ends and a Sliding Wiper ▪ Used as a Voltage Divider ◦ 2-Wire Terminal Resistor ▪ One end and Wiper (Rheostat) ▪ Used as a Variable Resistor • Two Basic Types ◦ Rotary and Linear (Slider) • Who Invented the Sensor? ◦ Johann Christian Poggendorff (1796-1877) in 1841 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  4. 4. Potentiometer/Slidewire Applications • How are they used? ◦ Manual Control of an Analog Signals (ie; Voltage Divider) ◦ Position Adjust(ie; Gates/Valves) ◦ Position Sensing/Feedback (Servo Controls) ◦ Speed/Motor Controls ◦ Temperature Controls ◦ Audio/Volume Controls ◦ Lighting/Dimmer Controls ◦ Circuit Gain/Bias/Attenuators • Many Consumer/Industrial Apps www.acromag.com www.acromag.com 248-624-1541 248-6241541
  5. 5. Potentiometer Construction • Wirewound • Carbon • Cermet • Metal Film • Conductive Plastic www.acromag.com www.acromag.com 248-624-1541 248-6241541
  6. 6. Measurement Technique • 3-Wire Sensor (Position-Best) ◦ Stable Excitation Source ◦ Low Voltage/Power Exc ◦ Pot Value >=1000ohms for lead wire resistance to be negligible ▪ 20Awg, 0.01ohm/ft ◦ Pot Value as low as possible for source impedance purposes (ie; 10Kohm is 2500 ohms of source impedance) ◦ % of Excitation Measurement ◦ Op Temp Changes - Immune • 2-Wire Sensor (Position-Good) ◦ Resistance Measurement ◦ Op Temp Changes - Affected www.acromag.com www.acromag.com 248-624-1541 248-6241541
  7. 7. Acromag New Solutions Model TT234-0600 --USB Config --Sink/Source 4-20mA Outputs -- -40 to 80C Amb -- CE, UL/cUL Div2 Model TT334-0700 --USB Config --Universal V/I Outputs -- -40 to 80C Amb --CE, UL/cUL Div2 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  8. 8. Thermistor Sensors • What Are They? ◦ “Thermal Resistors” ◦ Variable Resistance to Temperature ◦ Low Ranges (-90 to 130C), High Res ◦ 2-Wire Connection, Fast Response • Two Basic Types ◦ PTC – Positive Temp Coeff. ◦ NTC – Negative Temp Coeff. • Who Invented the Sensor? ◦ Discovered 1833, Michael Faraday ▪ Silver Sulfide behavior ◦ Invented 1930, Samuel Ruben www.acromag.com www.acromag.com 248-624-1541 248-6241541
  9. 9. Thermistor Applications • How are they used? ◦ PTC – current limiter, fuse ◦ PTC – degaussing circuits in CRT ◦ PTC – heaters ◦ NTC – PS inrush current limiter ◦ NTC – Temperature Monitoring ▪ Resistance Thermometers ▪ Incubators, 3D Printers, Batteries ▪ Automotive Coolant/Oil ▪ Engine Manifold Temps ▪ Food Industry, Processing Equip ▪ Consumer Appliances – Toasters, Coffee Makers, Freezers, Dryers www.acromag.com www.acromag.com 248-624-1541 248-6241541
  10. 10. Thermistor Construction • PTC ◦ Doped Polycrystalline Ceramic ▪ BaTiO3 ◦ Plastic/Carbon Grains ◦ W. Heywang & G H Jonker modeled in 1960’s • NTC ◦ Semiconductor ▪ Pressed Disc or Cast Chip • Steinhart-Hart Equation 1/T =A+B(ln R)+C(ln R)^3 T=Kelvins, R= Resistance A,B,C = Steinhart-Hart parameters www.acromag.com www.acromag.com 248-624-1541 248-6241541
  11. 11. Temperature Sensor Comparisons Advantages & DisAdvantages --Source: Agilent Technologies www.acromag.com www.acromag.com 248-624-1541 248-6241541
  12. 12. Measurement Technique • 2-Wire Sensor (NTC-Temps) ◦ Voltage Divider Measurement ◦ Stable Excitation Source ◦ <=3K Thermistor Ranges, typ ▪ 0-150C (10K to 0 ohms) ▪ -40 to 150C (100K to 0 Ohms) ◦ 5K-10K Thermistor Ranges,typ ▪ 0-150C (30K to 0 ohms) ▪ -40 to 150C (240K to 0 ohms) ◦ High Ohms/C output ◦ Needs Linearization to Temp ◦ Leadwire Resistance - Neg www.acromag.com www.acromag.com 248-624-1541 248-6241541
  13. 13. Acromag New Solutions Model TT234-0600 --USB Config --Sink/Source 4-20mA Outputs -- -40 to 80C Amb --CE, UL/cUL Div2 Model TT334-0700 --USB Config --Universal V/I Outputs -- -40 to 80C Amb --CE, UL/cUL Div2 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  14. 14. Acromag New Solutions – Thermistor Continued www.acromag.com www.acromag.com 248-624-1541 248-6241541
  15. 15. Acromag New Solutions – Thermistor Continued www.acromag.com www.acromag.com 248-624-1541 248-6241541
  16. 16. Resistance Temperature Detector (RTD) Sensors • What Are They? ◦ Variable Resistance Sensors ◦ Used for Temperature Measurement ◦ Uses the temperature coefficient of base metals • Three Basic Sensor Types ◦ Platinum (100/200/500/1000 ohm) ◦ Copper (10 ohm) ◦ Nickel (120 ohm) • Who Invented the Sensor? ◦ Werner Von Siemens, 1871 ◦ Hugh Longbourne Callendar, 1885 ◦ Callendar-Van Dusen, 1925 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  17. 17. RTD Applications • How are they used? ◦ Precision Temperature Measurements ▪ Contact ▪ Non-Contact ◦ Range: -200 to +500C range ◦ Heaters, Liquids, Air Flow, MCC ◦ Motor Winding’s/Bearing Temp ◦ HVAC, Environmental Controls ◦ Sanitary/Pharm/Food/Dairy/Bev ◦ Alt. to TC’s and Thermistors • Many Consumer/Industrial Apps www.acromag.com www.acromag.com 248-624-1541 248-6241541
  18. 18. RTD Construction • Thin Film • Wire-Wound • Coiled • Others: ◦ Carbon ◦ Strain Free • 2,3,4-Wire Sensor Connection ◦ 2, No Lead-wire Compensation ◦ 3, Good Lead-wire Compensation ◦ 4, Best Lead-wire Compensation www.acromag.com www.acromag.com 248-624-1541 248-6241541
  19. 19. Temperature Sensor Comparisons Advantages & DisAdvantages --Source: Agilent Technologies www.acromag.com www.acromag.com 248-624-1541 248-6241541
  20. 20. Measurement Technique • 2-Wire Connection (Poor) ◦ No-lead wire compensation ◦ Keep lead wires short ◦ Can be “failsafe” • 3-Wire Connection (Good-typ) ◦ Includes lead-wire compensation (ie; 3rd wire benefit) ◦ Lead wires should be balanced ◦ Can go long distances, 10ohms per leg typical • 4-Wire Connection (Best) ◦ Includes lead wire compensation (2 Exc, 2Sense) ◦ Kelvin Type Connection ◦ Leads don’t need balance www.acromag.com www.acromag.com 248-624-1541 248-6241541
  21. 21. Acromag New Solutions Model TT235-0600 --USB Config --Sink/Source 4-20mA Outputs -- -40 to 80C Amb --CE, UL/cUL Div2 Model TT335-0700 --USB Config --Universal V/I Output (+/-10Vdc,+/-20mA, 4-20mA) -- -40 to 80C Amb --CE, UL/cUL Div2 www.acromag.com www.acromag.com 248-624-1541 248-6241541
  22. 22. TT230 – Universal 4-20mA w/ Sink/Source Output www.acromag.com www.acromag.com 248-624-1541 248-6241541
  23. 23. TT330 – Universal Voltage/Current Output www.acromag.com www.acromag.com 248-624-1541 248-6241541
  24. 24. Summary • Potentiometers/Slidewires ◦ Position Sensor, Resistance, Linear ▪ 3-Wire Sensed as Voltage Divider ▪ 2-Wire Sensed as Rheostat ◦ Used for Manual Control/Adjust ◦ 3-Wire Connection – Best, typical (Position) ◦ 1000ohm, 2000ohm, or <10Kohm best • Thermistors ◦ NTC most popular for Temperature Sensing ◦ 2-Wire Sensor, Narrow Ranges: 0-100C, ◦ Low Cost, Fast Acting, but Non-Linear • RTD’s ◦ 100ohm PT, 385 most popular ◦ Wider Temperature -200 to 500C ◦ Slow Response, High Accuracy, Stable www.acromag.com www.acromag.com 248-624-1541 248-6241541
  25. 25. Thank you! • Questions? • For More Information: ◦ www.acromag.com/tt ◦ Tel. 248-295-0880 ◦ Email: sales@acromag.com www.acromag.com www.acromag.com 248-624-1541 248-6241541

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