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Unformatted text preview: 1 ME 365 EXPERIMENT 5 FIRST ORDER SYSTEM IDENTIFICATION APPLIED TO TEMPERATURE MEASUREMENT SYSTEMS Objectives: In this two week experiment, we will gain familiarity with first order systems by using two commonly used temperature transducers. The transducers are the copper-constantan (T-Type) thermocouple and the platinum resistance temperature detector (RTD). A common step in the design process for most mechanical systems is to select appropriate sensors based on their performance characteristics. Here, we will be examining a few measures of static and dynamic performance associated with the thermocouple and RTD. If these were part of a complete design project that required temperature measurement, we could then use this information, along with factors such as cost and durability, to choose the best sensor for the job. After completing this lab you should be able to: • Perform a static calibration on a simple temperature transducer. • Experimentally determine static performance characteristics and understand what they mean. • Use two different methods to experimentally determine the time constant of a first order system and understand the significance of the time constant. Procedure: Static Calibration (First Week): We will begin our study of the static and dynamic performance characteristics of the thermocouple and RTD sensors by calibrating both instruments. You should have access to the following equipment to perform this experiment: Copper-Constantan Thermocouple (TC) Platinum Resistance Thermometer (RTD) Glass Thermometer Hot Plate Beaker Dewar Flask 6 Volt Battery Wheatstone Bridge Patchboard 2 - 5 K• , and 1 - 124 • resistors BNC Shunt Rubber Bands Crushed Ice and Distilled Water Laboratory 5 First Order Systems and Temperature Measurements ME 365 2 Carefully bundle the TC, RTD, and thermometer together with a rubber band. Take care not to bend the TC or RTD leads when handling them. At this time, prepare an ice bath by packing the Dewar flask with ice, and adding distilled water. We won't be using the ice bath as a temperature reference for the TC, since that is being done with an integrated circuit in the ADC interface, but we will take measurements at the ice point for the calibration curve. To ensure that the RTD's output voltages lie within the specified ±20 mV ADC range, the temperature extremes must be measured. Immerse the sensor bundle in the ice bath and observe the RTD's output voltage on the DMM. Then immerse the sensor bundle in a beaker containing a small amount of boiling water and again observe the output voltage. Adjust the potentiometer on the Wheatstone Bridge so that these voltages, representing the extremes of the test, lie within the specified range....
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- Fall '07
- RTD, Resistance thermometer, temperature measurements