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Mechanical Measurement and Instrumentation MECN 4600

Mechanical Measurement and Instrumentation MECN 4600. Professor: Dr. Omar E. Meza Castillo omeza@bayamon.inter.edu http://www.bc.inter.edu/facultad/omeza Department of Mechanical Engineering Inter American University of Puerto Rico Bayamon Campus. Tentative Lecture Schedule.

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Mechanical Measurement and Instrumentation MECN 4600

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  1. Mechanical Measurement and Instrumentation MECN 4600 Professor: Dr. Omar E. Meza Castillo omeza@bayamon.inter.edu http://www.bc.inter.edu/facultad/omeza Department of Mechanical Engineering Inter American University of Puerto Rico Bayamon Campus

  2. Tentative Lecture Schedule

  3. Topic 7: Measurement of Temperature RTD & Thermistor

  4. Course Objectives • To measure temperature using a RTD & Thermistor.

  5. RTD Types of RTD

  6. RTD • RESISTANCE TEMPERATURE DETECTORS (RTDs).- • RTD’s functions as a result of increasing resistance in proportion to increasing temperature. i.e, with a known current, as temperature increases, voltage increases. As a known current is placed through the RTD, the output voltage indicates RTD resistance. Since the relationship between the resistance and temperature is known, the temperature can thus be determined. • The resistivity of the metal used in a RTD is dependent upon the temperature. Platinum has the best range and is the most common metal used.

  7. Glass Wire Wound Platinum RTD Elements - Class B • Suitable for Low or very High Temperatures • Tolerant of Thermal Shocks • Good Vibration Resistance • Alpha = 0.00385

  8. RTD (PT100) Probes • Temperature Range -200 to 600°C • Alpha = .00385 Standard • Ro = 100Ω @ 0°C

  9. RTD • The general equation is: • La ecuación general puede ser simplificada para materiales comunes como platino, cobre, etc con bajos porcentajes de error en las mediciones.

  10. RTD • Where: • R= Resistance at temperature T • Ro= Resistance at temperature To • To= Temperature of reference • T= Temperature • α= Resistivity Coefficient

  11. Rb I + D M M ei (fem) eo RRTD Theory  Experiment • Circuit for the laboratory Where: • eo= Voltage through RTD • Rb= Resistance • RRTD= Resistance RTD • ei= Voltage of fem

  12. Analysis • Kirchoff’sLaw: • Law of Ohm

  13. Analysis • CombiningpreviousEquations:

  14. Laboratory: Find the value of α • Table of Data • Setup the circuit with a ei=10V • Measure the Ro at T=0ºC • Obtain the value of Rb • Increase temperature and measure eo • In order to find α, use the following equation • Obtain the value of α using least squared method • Compare α with values of literature.

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