VAL JOHN C. MENDOZA SEPTERMBER 8, 2021 BSEE 4A RESISTANCE TEMPERATURE DETECTOR INTRODUCTION Temperature is one of the factors that can affect the amount of resistance a conductor may have. By definition, is a measure of the average heat or thermal energy of the particles in a substance or simply the hotness or coldness of a substance. Resistance, on the other hand, of an object is the measure of opposition to the flow of electric current. Resistance also varies accordingly with materials used in a certain conductor. This is justified by the equation: R = ρl/A Where 'R' is resistance of the metal, 'ρ' is the resistivity of the metal, 'l' is the length of the metal and 'A' is the area of cross section of the metal. With the use of Resistance Temperature Detector (RTD) we will be able to know how temperature and resistance is related to each other with different materials used. These are the materials commonly used in RTD; includes platinum, copper, nickel, balco, tungsten. Temperature increases directly with resistance, this is justified by the equation: Rt = R0[1+ α (t-t0)] Where: Rt = resistance at temperature 't' R0 = resistance at a reference temperature ( Generally 0 degree C) α = temperature coefficient of resistance (°C‾1) RTD materials must have the following criterion; malleability to form small wires, linear relationship of resistance and temperature, repeatability and stability, corrosion, low cost, and easy availability. In addition to this, the specifications of RTD performance includes temperature coefficient, accuracy, stability, interchangeability, response time, insulation resistance, and selfheating. EXPERIMENT These are the data I gathered and collated after I’ve done the experiment using Resistance Temperature Detector by Sensor Analysis Laboratory. The first level is the Static Characteristics which is to select R0 given a material to get the temperature. With all those information, Rt values will be determined. All the data gathered were verified and computed using calculator to ensure that the values are correct. For platinum used as material: R0 100 200 T(°C) 523 122 791 88 352 384 Rt 301.36 146.97 404.54 267.76 471.04 495.68 For copper used as material: R0 100 200 T(°C) 16 238 70 152 -67 -55 Rt 106.832 201.63 129.89 329.808 142.78 153.03 For the second level which is the dynamic characteristics of an RTD, the students are assigned to select an RTD as bare element, with sheath, and thermowell which is performed in three separate experiments. These are the data gathered for RTD as bare element. Platinum RTD is used in this experiment to obtain or compute for the time constant values. The time constant value for this is 1.17 seconds. For the with sheath, these are the data gathered: Material Platinum With Sheath SS 304 SS 316 SS 410 .5 2.72 2.71 2.39 .75 3.42 3.41 2.92 Thickness (mm) 1 4.13 4.11 3.46 1.5 5.53 5.51 4.53 2 6.94 6.91 5.61 For the thermowell, these are the data collated: Material P L A T I N U M Thermowell Thickness Filling Material .5 S S .75 1 3 0 4 1.5 2 Output 8.52 Mg O P O W D E R Using SS 304 as material and MgO powder as filling material ` 9.93 11.33 12.74 Material P L A T I N U M Thermowell S S Thickness Output .5 36.23 .75 ` 1 3 0 4 Filling Material SILICON COMPOUND 37.63 1.5 39.04 2 40.45 Using SS 304 as material and Silicon Compound as filling material Material P L A T I N U M Thermowell Thickness Filling Material .5 S S .75 1 3 1 6 1.5 2 Output 8.51 Mg O P O W D E R ` 9.91 11.31 12.71 Using SS 316 as material and MgO powder as filling material Material P L A T I N U M Thermowell Thickness S S .5 36.22 .75 ` 3 1 6 1 Filling Material SILICON COMPOUND Output 37.62 1.5 39.02 2 40.42 Using SS 316 as material and Silicon Compound as filling material Material P L A T I N U M Thermowell Thickness Filling Material .5 S S .75 1 4 1 0 1.5 2 Output 8.19 Mg O P O W D E R ` 9.26 10.33 11.41 Using SS 410 as material and MgO powder as filling material Material P L A T I N U M Thermowell S S Thickness Output .5 35.89 .75 ` 1 4 1 0 Filling Material SILICON COMPOUND 36.97 1.5 38.04 2 39.12 Using SS 410 as material and Silicon Compound as filling material CONCLUSION In this experiment, I found out that the resistance of an object is directly proportional to the temperature. When the temperature is being increased, the resistance also increases. The resistance of an object also depends on what material is being used. Just like platinum and copper, because their temperature coefficient of resistance also varies. For the second level of experiment, the time constant value for bare element platinum is 1.17 seconds. The time constant values of RTD varies directly as the thickness. When the thickness increases, the time constant values also increase depending on what type of material is used, whether SS 304, SS 316, or SS 410. For SS 304, SS 316, and SS 410 and MgO used as filling material, as thickness increases, time constant values also increase. But when these materials have silicon compound as their filling material, the response time of RTD is now 5 times the time constant values. The values of response time and time constants vary with the materials used for bare element, with sheath, and thermowell. These values also changes as filling materials also change.