Introduction to Measurement Systems & Devices

1. Module-3 Introduction toMeasurement Systems & Devices

2. Upon successful completion of this module, students should be able to: Define a measurement system and identify its main elements Explain the role of sensors/transducers in a measurement system Define the terms sensitivity and linearity of a sensor/transducer Identify different sensors used in temperature measurements Determine the sensor characteristics through experiments Understand and perform calibration of temperature sensor/transducer. Module Objectives

3. We use the term ‘measurements’ everyday in our lives • Noting the time on our watch/clock • Recording the temperature • Tracing the speed of a car • Estimating electricity consumption, and so on Introduction to Measurement Systems

4. An instrument is a device used to measure a physical variable. A ruler, for example, provides measurement of length Instruments temperature, distance, pressure, force, humidity

5. A process is a sequence of operations carried out to achieve a desired result. For example, fixing a flat tire is a process. Similarly, maintaining the temperature of a room within the desired limit is a process. Process Manual Automatic

6. Any Measurement system consists of three basic parts: • transducer/sensor • signal processor and • recorder Measurement System Elements

7. www.quia.com Complete the classwork on quia

8. A sensor is a device that senses a physical variable, such as temperature, force, or pressure etc Sensor

9. A transducer is a device that converts a physical quantity into a measurable quantity, usually an electrical signal transducer

10. Temperature measurement system Measurement System Example

11. Transducer – Thermocouple is the transducer that converts the input temperature to a small voltage (in millivolt). Signal processor –The signal processor increases the level of the voltage and converts it to a digital format. Recorder- LED display displays the temperature in digits. Definition

12. TASK-1 : Go to Quia & Answer the question

13. Some transducers output a signal that is proportional to the input physicalquantity. These transducers are called linear devices. Other transducers that don’t have a proportional relationship between the output signal and the input are non-linear devices. Linearity

14. Sensitivity is the ratio of change in the output signal to the change in the amount of the physical parameter being measured. sensitivity Sensitivity = Change in Output / Change in Input

15. Calibration is the comparison of measurement with a standard Calibration

16. Calibration is done by: Measuring the transducer output for known physical quantities Determining the best mathematical relation between the input and the output Calibration

17. Temperature is the degree of hotness or coldness measured on a definite scale. • The various units for measuring temperature are • celsius, • kelvinand • fahrenheit. • The SI unit of temperature measurement is the ‘kelvin’. Temperature Measurement

18. Temperature can be measured using any one of the following methods depending on the application: • Immersion in a gas or liquid • Surface Contact with the solid • No contact Temperature Measurement Measuring device: thermometer, thermistor and thermocouple

19. Mercury thermometer is a temperature sensor that converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. Thermometer

20. Thermocouple is a temperature transducer that consists of two different metals, joined together at one end Thermocouple

21. The thermistor is a thermally sensitive resistor, the resistance of which varies with temperature. Thermistor

22. Identify the input physical quantity and the output for the sensors given in the table. Task-2

23. Lab Activity 1