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DIFFERENCE BETWEEN ABSOLUTE AND SECONDAY INSTRUMENTS
- 1. EE304.1 1 Name ofthe faculty : K.V.Ramana Babu, Designation : HEEES, Branch : Electrical and Electronics Engineering Institute : S.V.G.Polytechnic,Tirupathi Year/Semester : II Year / III semester Subject : Measuring Instruments and Batteries Sub.Code : EE-304, Topic : Basic Measuring Instruments Duration : 50 Min. Sub Topic : Distinguish between Absolute and Secondary Measuring Instruments. Teaching Aids : 1PPT, Animation, Photograph DEPARTMENT OF TECHNICAL EDUCATION ANDHRA PRADESH
- 2. EE304.1 2 Objectives On completionof this period, you would be able to know • Absolute Instruments. • Secondary Instruments.
- 3. EE304.1 3 Measurement isa process in which the magnitude of a quantity is compared with another similar quantity. Measurement is the process by which one can Convert physical parameters to meaningful number Measurement OR
- 4. EE304.1 4 Measuring Instruments •The instrument used to measure any quantity like electrical or non-electrical is known as measuring instrument. For example; • Speedometer, • Ammeter etc.
- 5. EE304.1 5 Necessity OfMeasuring Instruments • In day-to-day life the electrical and non-electrical quantities measurement is very essential. • Because we need to know the electrical quantities in sub-stations, laboratories etc. • We also need to know the speed, temperature of the machines in work-shops or laboratories etc. for better performance.
- 6. EE304.1 6 • Theinstrument used to measure the electrical quantity is known as electrical measuring instrument. Electrical measuring instruments
- 7. EE304.1 7 Examples OfElectrical Measuring Instruments • AMMETER : used to measure the current • VOLTMETER : used to measure the voltage • OHMETER : used to measure the resistance • WATTMETER : used to measure the power • POWER FACTOR METER: used to measure the power factor
- 8. EE304.1 8 Classification OfInstruments Measuring instruments are classified as follows: • Absolute instruments • Secondary instruments • Indicating instruments • Integrating instruments • Recording instruments
- 9. EE304.1 9 Absolute Instruments Givesthe value of the quantity to be measured, in terms of instrument constant and deflection.
- 10. EE304.1 10 Absolute instrumentsdo not require any previous calibration or comparison. Example: Uses : As standardizing instruments in standard laboratories like R&D. 1) Tangent galvanometer 2) Rayleigh’s current balance instruments
- 11. EE304.1 11 Secondary instruments •The value of the electrical quantity to be measured can be determined from the deflection of instruments directly. • The instrument doesn't have any meter constant.
- 12. EE304.1 12 • Needto be calibrated with an absolute instrument. • Without calibration, the deflection of the instruments is meaningless. Requirements of secondary instruments
- 13. EE304.1 13 Examples ofSecondary Instruments & Applications • Ammeter : used to measure the current • Tachometer : used to measure the speed • Thermometer : used to measure the temperature • Sismograph : used to measure the intensity of earth-quake.
- 14. EE304.1 14 Difference betweenAbsolute and Secondary Instruments All the instruments we see in the market are secondary type It is used in R&D laboratories 3 It is cheap compared to absolute instrument It is costly instrument 2 The reading is directly obtained from the meter reading The reading obtained in terms of meter constant 1 Secondary Instrument Absolute Instrument S.No
- 15. EE304.1 15 Summary Types ofmeasuring instruments • Absolute instruments • Secondary instruments • Indicating instruments • Integrating instruments • Recording instruments
- 16. EE304.1 16 Quiz 1.The absoluteInstrument is a) Voltmeter b) Ammeter c) Galvanometer d) None of the above
- 17. EE304.1 17 Quiz 2.The secondaryinstrument is a) Tangent galvanometer b) Rayleigh’s current balance instruments c) Voltmeter d) None of the above
- 18. EE304.1 18 Quiz 3.The instrumentused in Standard Laboratories is: a) Tangent galvanometer b) Rayleigh’s current balance instruments c) Voltmeter d) None of the above
- 19. EE304.1 19 Frequently AskedQuestions • What is the difference between Absolute Instruments and Secondary Instruments? • How the Measuring Instruments are classified?