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Measurements & Measuring Instruments AIE 141 Dr. Hany S. E. Mansour Electrical Engineering Department, Faculty of Engineering, Suez Canal University Email:...

Measurements & Measuring Instruments AIE 141 Dr. Hany S. E. Mansour Electrical Engineering Department, Faculty of Engineering, Suez Canal University Email: [email protected] Phone: 010 243 27 200 Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 Contents Chapter one: Introduction to Measuring System Chapter Two: Indicating Instruments Chapter Three: Bridges Instruments Chapter Four: Digital Multimeters Chapter Five: Oscilloscope Chapter Six: Frequency and Power Factor meters Chapter Seven: Function Generator Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 2 References Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 3 Assessment Reports & Sheets 10 Midterm Exams 20 Project / Presentation 10 Lab 10 Final Exam 50 Total 100 Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 4 Chapter 1: Introduction to Measuring System ❖ Systems of Units To measure the fundamental quantities length, mass and time there are three standardized systems of units. 1) F.P.S. System 2) C.G.S. System 3) M.K.S. System Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 5 SI System Fundamental quantity - the quantity which is independent of any other quantity, is fundamental quantity. Fundamental (Base) unit - the unit of a physical quantity, which is independent of any other quantities, is called a fundamental unit. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 6 SI System Derived Quantities - the physical quantities which can be derived by combining two or more of the fundamental quantities. Derived Units - the units of physical quantities, which can be expressed in terms of fundamental units, are called derived units. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 7 SI System Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 8 Multiplication Factors of Units Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 9 Principles of Measurement ❖ Measurement is the process of comparing an unknown quantity with an accepted standard quantity as shown in Fig. 1. ❖ Measurand The physical quantity or the characteristic condition which is the object of measurement in an instrumentation system. Also called: ✓ Measurement variable ✓ Instrumentation variable ✓ Process variable The measurand may be: ✓ Fundamental quantity, e.g. length, mass, and time; ✓ Derived quantity, e.g. speed, velocity, acceleration. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 10 Principles of Measurement Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 11 Instruments and Instrumentation Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 12 Why do we need measurements? Measurement plays a very significant role in every branch of scientific research and engineering processes which include the following: ✓ Control systems ✓ Process instrumentation The whole area of automation or automatic control is based on measurements. The very concept of control is based on the comparison of the actual condition and the desired performance. The exactness of error depends on the precision and accuracy of measurement made. The measurements confirm the validity of a hypothesis and also add to its understanding. This eventually leads to new discoveries that require new and sophisticated measuring techniques. Through measurements a product can be designed or a process be operated with maximum efficiency, minimum cost, and with desired degree of reliability. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 13 METHODS OF MEASUREMENT Deflection Methods Direct Methods Measurement Comparison Methods Methods Indirect Methods ❖ In direct measurement methods, the unknown quantity is measured directly. ✓ In deflection methods, the value of the unknown quantity is measured by the help of a measuring instrument having a calibrated scale indicating the quantity under measurement directly, such as measurement of current by an ammeter. ✓ In comparison methods, the value of the unknown quantity is determined by direct comparison with a standard of the given quantity, such as measurement of emf by comparison with the emf of a standard cell. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 14 METHODS OF MEASUREMENT Deflection Methods Direct Methods Measurement Comparison Methods Methods Indirect Methods ❖ In indirect measurement methods, the comparison is done with a standard through the use of a calibrated system. These methods for measurement are used in those cases where the desired parameter to be measured is difficult to be measured directly, but the parameter has got some relation with some other related parameter which can be easily measured. For instance, the elimination of bacteria from some fluid is directly dependent upon its temperature. Thus, the bacteria elimination can be measured indirectly by measuring the temperature of the fluid. Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 15 Basic Electrical Instruments and their functions Dr. Hany S. E. Mansour Measurements & Measuring Instruments Lec. #1 16