Wiley acing the gate electrical engineering part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Wiley acing the gate electrical engineering part 2
Wiley acing the gate electrical engineering part 2
SECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 13 2012 2011 2010 2009Measurement of basic electrical quantities, Electronic measuring instrument Measuring instruments PMMC, Moving iron, AC bridges PMMC. Bridges, Multiplier Wattmeter, AC bridge, Error analysis Wattmeter, Ammeter, AC bridge Dynamometer, Oscilloscope, WattmeterCHAPTER 7ELECTRICAL A Wiley acing the gate electrical engineering part 2 ND ELECTRONIC MEASUREMENTSMeasurement. techniques have played a significant role from the starting hum fair exchange of goods in early civilizations tWiley acing the gate electrical engineering part 2
o regulation of trade in industrialised societies. Better measurement and instrumentation techniques evolved as production of goods became industrialiSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 ments used com monly for electrical and electronic measurements and about their error analysis. These include instruments for measurement of voltage, current and power; instrument transformers; oscilloscopes and transducers.7.1 CLASSIFICATION OF MEASURING INSTRUMENTSInstruments can he classified bas Wiley acing the gate electrical engineering part 2 ed on their mode of operat ion, manner of energy conversion, measuring techniques and kind of output signal. The main instrument types are discussed aWiley acing the gate electrical engineering part 2
s follows.1.Primary (or absolute) and secondary type: Instruments that measure the absolute physical quantity directly in terms of the constants of thSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 sured is proportional to some other absolute value of the quantity, the instrument is called secondary'. The instrument is prc-cahbratcd using the absolute instrument (e.g., voltmeter. ECG recorder, etc.)2.Active and passive type: Instruments that can be directly used for the quantity being measured Wiley acing the gate electrical engineering part 2 arc known as the active-type. If the quantity being measured simply modulates the magnitude of some external power source the instrument is known asWiley acing the gate electrical engineering part 2
passive type.3.Deflection and null type: In a deflection-type instrument, the physical effect, generated by the quantity being measured, produces an eSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 C MEASUREMENTSdisplacement) which is a measure of the quantity. Ill the null-type instrument the physical effect generated by the physical quantity under measurement is nullified by either a manual or automatic balancing device. The equivalent null causing effect is the measure of the quantity.4.Ana Wiley acing the gate electrical engineering part 2 log and digital type: In analog instrument, the physical quantities under measurement show continuous (step-less) variation with time. In digital instWiley acing the gate electrical engineering part 2
ruments, the physical quantities are discrete and vary in steps with time.Rased on the mode of operation, the secondary instruments are further classiSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 e of indicator. Majority of the measuring instruments fall under this category, for example, voltmeter, ammeter, etc.2.Integrating type: In this category of measuring instruments, the measurement is done with the help of integrating device or arrangement over a period of time. For example, in the ca Wiley acing the gate electrical engineering part 2 se of energy meter the rotation of disc over a period of time gives the reading of the energy consumed.3.Recording type: In thus category, the measuriWiley acing the gate electrical engineering part 2
ng instrument is used to record certain quantities to be used for analysis. For example, plot chart recorder. ECG, EEG. etc.7.1.1Indicating Type InstrSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 torque, is developed by the magnetic, electro static, chemical or thermal effects produced by the quantity to be measured.Td Operating quanity2.Controlling torque: The instruments are so designed that the controlling torque acts on its moving part. It can (i) control/stop the movement of the pointe Wiley acing the gate electrical engineering part 2 r beyond the desired reading and (ii) bring the pointer back to its zero position, when the operating quantity is removed. The controlling torque {Tc)Wiley acing the gate electrical engineering part 2
is usually obtained either by a spring control.Tc « 8 (deflection) => Tc = kr8 where kc is the spring constant or by gravity control mechanismTc« WVsSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 vity constant.Note: In instruments with spring control graduated scales are used and cramped scales are used for gravity control instruments.3.Damping torque: In an instrument, the combined effect of deflecting and controlling torques on the movement of the pointer on the scale, causes it to oscilla Wiley acing the gate electrical engineering part 2 te when indicating the final reading. These oscillations are prevented by using a damping mechanism, either by generating air or fluid friction or byWiley acing the gate electrical engineering part 2
action of eddy currents. This torque is proportional to the angular velocity of the moving system and hence operated only when the system is in motionSECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201 Wiley acing the gate electrical engineering part 2 ped and over-damped instruments, respectively.Figure 7.1 I Effect of damping on deflection.7.2 TYPES OF INDICATING INSTRUMENTSThe basic components of all indicating instruments include: Wiley acing the gate electrical engineering part 2 SECTION VII: ELECTRICAL AND ELECTRONIC MEASUREMENTSMARKS DISTRIBUTION FOR GATE QUESTIONSTOPIC DISTRIBUTION FOR GATE QUESTIONSYearConcepts2015 2014 201Gọi ngay
Chat zalo
Facebook