INSTITUTE OF AERONAUTICAL ENGINEERING DUNDIGAL-500043, HYDERABAD Department of Electrical and Electronics Enigineering HAND OUT OF ELECTRICAL MEASUREMENT Course code : 56009 Course title : Electrical measurements Course structure Lectures Tutorials Practical credits 04 01 Course coordinator : Mr.T.Anil kumar, ASSOCIATE PROFESSOR UNIT 1 AN GREAT SCIENTIST SAID THAT AN EDUCATION WHICH CANNOT BE EXPRESSED IN NUMERICALS IS OF NO USE.THAT IS EVERY PARAMETERS WE COME ACROOS IN TECHNICAL WORLD CAN MEASURED IN ONE OR THE OTHER WAY. THE POWER SYSTEM IS ASSOCIATED BY MANY PARAMETERS WHICH ARE SUPPOSED TO BE MEASURED AT ONE OR OTHER POINT. HENCE MEASUREMENT GOT GREATER IMPORTANCE IN POWER SYETMS THIS UNIT DEALS WITH CLASSIFICATION OF INSTRUMENT,CLASSIFICATION OF INSTRUMENT BASED ON THEIR INDICATION AND WORKING CONDITION,DEFINATION OF THE MEAUSRING INSTRUMENT ALONG WITH EXAMPLE,EFFECTS BASED ON WHICH THESE INSTRUMENTS OPERATE. COMMON TORQUES IN ELECTRICAL INSTRUMENTS: FOR THE SMOOTH FUNCTIONING OF MEASURING INSTRUMENT THEY ARE ASSOCIATED WITH DIFFERENT TYPES OF TORQUES.THEY ARE DEFLECTION, DAMPING AND CONTROL TORQUE. THE IMPORATNCE OF EACH TORQUE ANF DIFFERENT ARRANGEMENTS TO PROVIDE ABOVE SAID TORQUES ARE DISCUSSED HERE. IN MOST OF THE INSTRUMENTS THESE TORQUES ARE PROPORTIONAL TO CURRENT FLOWING THE CIRCUIT I.E CURRENT IS THE MOST IMPORTANT PARAMETER IN MEASURING DEVICES.
THE MAIN CLASIFICATIONS OF VOLTMETER AND AMMETER IN POWER SYSTEM ARE DEPENDING ON SUPPLY PROVIDED I.E HENECE THE CLASSIFICATION IS MC AND MI INSTRUMENTS, WHERE MC USED TO MEASURE DC QUANTITIES AND MI TO MEASURE AC QUANTITIES. THEREFORE IN THE PRECEEDING TOPICS WE SHALL DISCUSS ABOUT THE CONSTRUCTION AND OPERATION OF MC INSTRUMENTS, THEIR ADVANTAGES AND DISADVANTAGES, DIFFERENT TYPES OF ERRORS WHICH EFFECTS THE MEASUREMENT USING MC INSTRUMENTS, DIFFERENT METHODS TO EXTEND THE RANGE OF MC METERS AND SUGGESTING THE BEST METHOD FOR MEASUREMENT. LATER WE SHALL DISCUSS ABOUT THE CONSTRUCTION AND OPERATION OF MI INSTRUMENTS, THEIR ADVANTAGES AND DISADVANTAGES, DIFFERENT TYPES OF ERRORS WHICH EFFECTS THE MEASUREMENT USING MI INSTRUMENTS, DIFFERENT METHODS TO EXTEND THE RANGE OF MI METERS AND SUGGESTING THE BEST METHOD FOR MEASUREMENT. THE EXPRESSIONS FOR THE DEFLECTION TORQUE OF MC AND MI INSTRUMENTS ARE DERIVED, THEIR THE NATURE OF SCALE CAN BE DECIDED. IMPORTANT NOTE: ONE CANT USE THE VOLTMETER AS THEIR LIKE TO MEASUREMENT, IT IS NECESSARY TO IDENTIFY WHETHER THE GIVEN CIRCUIT IS LOW RESISTIVE OR HIGH RESISTIVE. THIS METHOD OF CHOOSING VOLTMETER DEPENDS ON ITS SENSITIVITY WHICH IS CALLED AS LOADING EFFECT. ELECTRO-STATIC VOLTMETERS: THE INSTRUMENT WHICH WORKS ON THE PRINCIPLE OF ELECTRO-STATIC IS VOLTMETER. LET US SEE THE CLSSIFICATION OF ELECTRO-STATIC VOLTMETERS, THEIR CONSTRUCTION AND OPERATION, THEIR ADVANTAGES AND DISADVANTAGES, DIFFERENT TYPES OF ERRORS WHICH EFFECTS THE MEASUREMENT USING ELECTRO-STATIC VOLTMETER INSTRUMENTS, DIFFERENT METHODS TO EXTEND THE RANGE OF THESE METERS AND SUGGESTING THE BEST METHOD FOR MEASUREMENT. BY THE END OF THIS UNIT ONE CAN BE ABLE IDENTIFY THE TYPE IF ELECTRICAL INSTRUEMNT, THE IMPORTANCE OF MC, MI AND ELECTROSTATIC INSTRUMENTS IN POWER SYSTEMS
UNIT 2 TILL NOW WE KNOW THAT TRANSFORMER IS A DEVICE USED FOR TRANSFORMATION OF ENERGY, BUT IN PRACTICE TRANSFORMER IS ALSO USED AS PROTECTIVE DEVICE AND ALSO AS MEASURING DEVICE. HERE IN THIS UNIT WE SHALL STUDY AN TRANSFORMER IN POWER SYSTEM AS A MEASURING DEVICE CALLED AS INSTRUMENT TRANSFORMER. DEFINATION OF INSTRUMENT TRANSFORMER, ITS SIGNIFICANCE IN POWER SYSTEM AND RATIOS ASSOCIATED WITH IT. THE APPLICATIONS OF INSTRUMENT TRANSFORMER ARE DISCUSSED. LATER THE MAIN CLASSIFICATION OF INSTRUMENT TRANSFORMER IS DONE, THE CONSTRUCTION AND OPERATION OF POTENTIAL AND CURRENT TRANSFORMERS ARE DISCUSSED. THE POTENTIAL TRANSFORMER IS USED TO MEASURE VOLTAGE IN HIGH VOLTAGE CIRCUITS AND THE CURRENT TRANSFORMER IS USED TO MEASURE CURRENT IN HIGH CURRENT CIRCUITS. THE MEASUREMENT OF VOLTAGE AND CURRENT USING INTRUMENT TRANSFORMERS ARE EFFECTED BY RATIO AND PHASE ANGLE ERROR. THE EXPRESSIONS FOR FOR RATIO AND PHASE ANGLE ERRORS ARE DERIVED FROM WHICH CHARACTERISTICS OF INSTRUEMNT TRANSFORMER ARE STUDIED. THE KNOWLEDGE OF PHASOR DIAGRAM OF INSTRUMENT IS VERY IMPORTANT TO CHARACTERISE THEM. THE LIMTATION OF INSTRUMENT TRANSFORMERS IS IMPORATANT BEFORE TAKING THEM INTO SERVICE. COMPARE THE POTENTIAL AND CURRENT TRANSFORMER FOR BETTER UNDERSTAND IN GENERAL TO DETERMINE THE POWER FACTOR OF CIRCUIT THE METHDO WE KNOW IS VOLTMETER AMMETER METHOD, BUT THIS METHOD OF MEASUREMENT MAY NOT LEAD TO PRECISION VALUE. THEREFORE AN NEW DEVICE INTRODUCED INTO THE CIRCUIT CALLED AS POWER FACTOR METER. POWER FACTOR METER WORKS ON THE PRINCIPLE OF MAGENTIC EFFECT AND MOTORING OPERATION. IN THE CONSTRUCTION OF POWER FACTOR METER IT GOT UNIQUE PROPERTY THAT CONTROL TORQUE IS NOT PROVIDED. DEPENIDING ON NATURE OF SUPPLY THEY ARE CLASSIFIED AS 1-PH AND 3-PH POWER FACTOR METER. IN INDIA NATURAL FREQUENCY IS 50 HZ AND MANY OF THE POWER SYSTEM CIRCUITS ARE MONITORED AT THIS FREQUENCY, HENEC IT IS NECESSARY TO CONTINUOUSLY CHECK THE
FREQUENCY OF SUPPLY. FREQUENCY IN DEFINATION NUMBER OF CYCLES MABE Y WAVE FORM IN ONE SECOND, IT IS ALSO GIVEN AS RECIPROCAL OF TIME. THE DEVICE USED TO MEASURE FREQUENCY IS CALLED AS FREQUENCY METER. DEPENDING ON MEACHANICAL AND ELECTRICAL RESONANCE THE FREQUENCY METERS ARE CLASSIFIED. LATER THE CONSTRUCTION AND OPERATION OF FREQUENCY METERS ARE STUDIED. THE SYNCHROSCOPE IS A DEVICE WHICH IS USED TO DETERMINE THE CORRECT INSTANT TO CLOSE THE SWITCH SUCH THAT INCOMING GENERATOR AND BUS BAR ARE SYNCHRONISED. THIS PPROCESS OF CLOSING SWITCH IS CALLED AS SYNCHRONIZATION. THE CONDITIONS FOR SYNCHRONIZATION OF ALTERNATOR AND BUS BAR ARE---- VOLTAGES MUST BE SAME. FREQUENCY MUST BE SAME. PHASE SEQUENCE MUST BE SAME. PHASE MUST BE SAME. IN THE PRECEEDING THE ADVANTAGES AND DISADVANTAGES OF POWER FACTORMETER, FREQUENCY METER AND SYNCHROSCOPE ARE STUDIED. IN THE POWER SYSTEMS THE INSTRUEMENT TRANSFOEMERS, FREQUENCY METER AND SYNCHROSCOPE GOT THEIR OWN IMPORATNCE, HENCE IT IS NECESSARY FOR EVERY ELECTRICAL ENGINEER TO HAVE THE KNOWLEDGE OF THESE INSTRUMENTS.
UNIT 3 THE WORD POWER GOT VERY IMPORTANCE IN ELECTRICAL WORLD. GENERALLY POWER IN ELECTRICAL CIRCUITS IS GIVEN AS PRODUCT OF VOLTAGE AND CURRENT. BUT DEPENDING ON THE NATURE OF SUPPLY THE DC POWER IS GIVEN AS V*I AND AC POWER IS V*I*COSINE OF PHASE BETWEEN V AND I. IN THE POWER SYSTEM WE COME ACROSS THREE TYPES OF POWER ACTIVE POWER, REACTIVE POWER AND APPARENT POWER. HERE IN THIS UNIT WE SHALL DISCUSS ABOUT MEASUREMENT OF ACTIVE AND REACTIVE POWER. MEASUREMENT OF POWER IN DC AND AC CIRCUITS. TO MEASURE THE POWER IN DC CIRCUITS THE BEST METHOD IS VOLT-AMP METHODS. THERE ARE TWO CONNECTIONS OF VOLT-AMP METHOD FOR MEASUREMENT OF POWER. BUT THESE TWO CONNECTIONS MAY NOT LEAD TO THE EXACT POWER MEASUREMENT CONSUMED BY LOAD. BUT THERE IS NO OTHER ALTERNATIVE METHOD TO MEASURE POWER IN DC CIRCUITS, HENCE IT IS NECESSARY TO CALCULATE ERROR IN THE MEASUREMENT USING THIS METHOD. TO MEASURE THE POWER IN AC CIRCUITS A DEVICE CALLED WATTMETER IS CAME INTO EXISTENCE. THIS WATTMETER IS MAINLY MEANT TO MEASURE USEFULL POWER ONLY.IN THE CONSTRUCTION OF WATTMETER IT CONSISTS OF PRESSURE COIL AND CURRENT COIL, WHERE THE PRESSURE IS EXITED BY VOLTAGE TO BE MEASURED AND CURRENT COIL BY CURRENT TO BE MEASURED. THE UNIQUENESS OF CURRENT COIL IS IT IS HIGHLY RESISTIVE AND PRESSURE COIL AND CURRENT COIL IS COMBINELY CALLED AS ELEMENT. AN DOUBLE ELEMENT WATTMETER IS USED TO MEASURE POWER IN POLY PHASE CIRCUIT. MEASUREMENT OF POWER IN POLY PHASE CIRCUIT IS GIVEN BY STATEMENT NAMED BLONDEL S THEOREM. THE BLONDEL S THEOREM IS PROVED FOR--- 1) 3 PHASE 3 WIRE SYSTEM. 2) 3 PHASE 4 WIRE SYSTEM.. 3) SINGLE WATTMETER METHOD. 4) TWO WATTMETER METHOD. 5) THREE WATTMETER METHOD.
LATER THE CONSTRUCTION OF DOUBLE ELEMENT WATTMETER AND ITS TORQUE EQUATION ARE DERIVED. THESE WATTMETERS ARE LIMITED FOR 600V AND 20 A IN GENERAL, BUT PRACTICALLY VERY HIGH VOLATGE AND HIGH CURRENTS MAY EXIST, TO MEASURE POWER IN SUCH CIRCUITS WE NEED TO INCREASE THE RANGE OF WATTMETER. THE EXTENSION OF RANGE OF WATTMETER CAN BE DONE USING INSTRUMENT TRANSFORMERS.THEN LPF AND FERRO-DYNAMIC WATTMETER CONSTRUCTION AND THEIR OPERATION IS STUDIED. THE MEASUREMENT OF POWER USING WATTMETER IS EFFECTED BY DIFFERENT TYPES OF ERRORS, THEY ARE----ERROR DUE TO INDUCATNCE OF PRESSURE COIL WICH LEADS TO DERIVATION OF CORRECTION FACTOR, ERROR DUE TO CONNECTIONS WHICH IS UNAVOIDABLE ONLY POSSIBILITY IS CHOOSING THE CORRECT CONNECTIONS DEPENDING ON NATURE OF LOAD, ERROR DUE TO FREQUENCY OF SUPPLY, ERROR DUE TO MUTUAL INDUCTANCE BETWEEN TWO COILS ETC. IT IS VERY MUCH NECESSARY TO CONTINUOUSLY MONITOR THE POWER IN DIFFERENT PARTS OF POWER SYSTEMS, TO KNOW THE POWER LOSSES IN POWER SYSTEM AT GENERATION, TRANSMISSION AND DISTRIBUTION LEVELS, TO DETERMINE THE EFFFICIENCY OF VARIOUS EQUIPMENTS IN POWER SYSTEMS MEASUREMENT OF POWER IS MOST IMPORATNT-----HENCE ABOVE SAID CAN BE MEET BY USING WATTMETER TO MEASURE THE POWER.
UNIT 4 ANY COUNTRY IS CALLED AS DEVELOPED COUNTRY DEPENDING ON THEIR ENERGY CONSUMPTION, TO MEET THAT DEMAND THE GENERATION HAS TO INCREASE RAPIDLY IN ONE OR THE OTHER WAY. WE KNOW THE POWER TRANSMISSION IN INDIA IS OPERATED AT 50 Hz FREQUENCY. THEREFORE THE ENERGY CONSUMPTION IN INDIA MEASURED IN TERMS OF ENERGY UNITS WHERE EACH UNIT REPRESENTS ONE KWH.THEREFORE MEASUREMENT OF ENERGY ALSO PLAYS IMPORATNT IN POWER SYSTEMS AND ALSO FOR THE ECONOMMY OF COUNTRY. IN THE DEFINATION ENERGY IS CAPACITY TO DO WORK OR AMONT OF POWER CONSUMED OVER A SPECIFIED PERIOD OF TIME. THE ENERGY MEASUREMENT CAN BE DONE IN DC AND AC CIRCUITS SEPRATELY.COMBINELY THE DEVICE USED TO MEASURE ENERGY IS CALLED AS MOTOR METERS. THE DEVICE USED TO MEASURE ENERGY IN DC CIRCUITS IS CALLED AS WATTHOUR METER AND AMPERE HOUR METER AND IN AC CIRCUITS ENERGYMETER. ENERGY METER IS AN ELECTRO-MAGNETIC DEVICE USED TO MEASURE ENERGY IN AC CIRCUITS. DEPENDING ON SUPPLY THEY ARE CLASSIFIED AS 1-PHASE AND 3-PHASE ENERGYMETER. IN THE CONSTRUCTION OF ENERGYMETER MAINLY IT CONSISTS OF PRESSURE COIL AND CURRENT COIL, WHERE PRESSURE COIL IS HIGHLY INDUCTIVE. UNLIKE DEFLECTION TORQUE IN INDICATING INSTRUMENTS ENERGYMETERS ARE ASSOCIATED WITH DRIVING TORQUE, AS MEASUREMENT OF ENERGYMETER IN DONE IN TERMS OF DRIVEN AL DISC. SIMILARLY LIKE CONTROL TORUE IN INDICATING INSTRUMENTS BRAKING TORQUE IS PROVIDED FOR ENERGYMETERS. THE REGISTERING SYSTEM IN MANY OF INSTRUMENTS IS AN ANGLED SCALE ON WHICH POINTER DEFLECTS WHERE AS IN ENERGYMETER CYCLOMETER TYPE REGISTERING SYSTEM IS USED.THE TORQUE GOVERNING THE ENERGYMETER IS PROPORTIONAL TO SPEED OF THE AL DISC OR TOTAL NUMBER OF REVOLUTION MADE BY AL DISC IN SPECIFIED PERIOD OF TIME.THE MEASUREMENT OF ENERGY USING ENERGYMETER IS EFFECTDE DIFFERENT TYPES OF ERRORS AND WE DEAL COMPENSATIONS FOR ERRORS.
MEASUREMENT OF ENERGY IN POLY PHASE CIRCUITS IS DONE POLY PHASE ENERGYMETER WHICH IS ALSO CALLED AS DOUBLE ELEMENT AND THREE ELEMENT ENERGYMETER. THE CONNECTIONS INTO CIRCUIT ARE SIMILAR TO TWO WATTMETER AND THREE WATTMETER METHOD RESPECTIVELY. TO TEST WHETHER THE MEASUREMENT GIVEN BY ENERGYMETER CORRECT OR NOT WE CAN TEST USING RSS METER.THE TESTS CONDUCTED ARE NAMED AS 1. TEST-A (LONG PERIOD DAIL TEST) 2. TEST-B(SHORT PERIOD DAIL TEST) 3. TECT-C(INDICATING INSTRUMENTS TEST) LATER THE CONSTRUCTION AND OPERATION OF TRIVECTOR METER, MAXIMUM DEMAND METER IS STUDIED. THE WORD ENERGY IS THE MOST IMPORTANT PART IN POWER SYSTEM. AFTER THIS UNIT AN STUDENT CAN BE ABLE OF MEASURING ENERGY IN SINGLE PHASE AND POLY PHASE CIRCUITS ALONG WITH BASIC KNOWLEGDE OF ITS CONSTRUCTION AND OPEARTION.
UNIT 5 TILL KNOW THE VOLTMETER WHAT WE HAVE STUDIED IS USEFUL IN MEASURING VOLTAGE GREATER THAN 50 V AND SO, BOTH IN DC AND AC CIRCUITS.BUT WE ARE SUPPOSED TO KNOW THE METHOD ARE DEVICE USING WHICH WE CAN MEASURE SMALL VOLATGES LESS THAN 2 V. THE BEST METHOD TO MEASURE LOWER VOLTAGES IN POWER SYSTEM IS USING POTENTIOMETER EITHER IN DC OR AC CIRCUITS. IN THE DEFINATION POTENTIOMETER IS A DEVICE USED TO MEASURE SMALL VOLTAGES IN POWER SYSTEMS AND POWER NETWORKS. HERE WE SHALL DISCUSS THE CONSTRUCTION AND OPERATION OF DC POTENTIOMETER. MEASUREMENT OF VOLTAGE USING POTENTIMETER IS AN COMPARISON METHOD, HENCE IT GOT AN ADVANTAGE OF MEASURING VOLTAGE AT LOW POWER CONSUMPTION AS IT WORKS ON NULL DFLECTION PRINCIPLE. IN THE CONSTRUCTION OF POTENTIOMETER IT MAINLY CONSISTS OF BATTERY, SERIES RHEOSTAT, SLIDE WIRE, STNADARD CELL AND THE ELEMENT ACROSS WHICH WE ARE SUPPOSED TO FIND VOLTAGE. IN THE WORKING OF POTNETIOMETER IT UNDERGOES TWO MODES CALIBRATION AND OPERATION. CALIBRATION IS DONE TO KNOW WHETHER THE POTENTIOMETER GIVES EXACT READING ARE NOT. IN THE PROCESS THE ADJUSTMENT OF WORKING CURRENT IN SLIDE WIRE SUCH THAT SLIDE WIRE COLTAGE MATCHES WITH STANDARD CELL VOLTAGE IS CALLED AS STANDARDIZATION. THEN OPERATE POSITION WHERE THE UNKNOWN VOLATGE IS MEASURED USING CALIBRATDE SLIDE WIRE. THEN THE MEASUREMENT OF HIGH VOLTAGES USING POTENTIOMETER IS DONE USING VOLT-RATIO BOX.DC POTENTIOMETER GOT MANY APPLICATIONS LIKE CALIBRATION OF AMMETER, VOLTMETER, WATTMETER AND MEASUREMENT OF RESISTANCE, POWER ETC. THE AC POTENTIOMETER IS AN DEVICE WHICH IS USE TO MEASURE AC VOLATGE, UNLIKE IN DC THESE POTENTIOMETERS ARE USED TO MEASURE BOTH MAGNITUDE AND PHASE OF OF AC VOLATGE. THESE POTENTIOMETERS ARE CALIBRATED WITH BOTH DC AND AC SUPPLY. DEPENDING ON
NATURE OF MEASURING VALUE THEY ARE CLASSIFIED AS POLAR TYPE AND CO-ORDINATE TYPE POTENTIOMETER. BY THE DEFINATION POLAR TYPE ARE ONE WHERE MEASUREMENT IS DONE AS MAGNITUDE AND PHASE OF UNKNOWN VOLATEG AND CO-ORDINATE TYPE ARE ONE WHERE UNKNOWN VOLTAGE IS MEASURED AS IN PHASE AND QUADRATURE COMPONENT OF UNKNOWN VOLATGE. AC POTENTIOMETERS ALSO GOT APPLICATIONS LIKE CALIBRATING VOLTEMETER, AMMETER, MEASUREMENT OF POWER, UNKNOWN REACTANCE ETC. IN THE POWER SYSTEMS THER ARE PARTS, DEVICES OR EQUIPMENT WHERE THE VOLATGE TO BE MEASURED IS SO SMALL, WHICH CANT BE DONE BY LABORATORY SIZE VOLTMETERS, HENCE THEIR COMES THE IMPORTANCE OF POTENTIOMETERS
UNIT 6 THE MOST IMPORTANT PARAMETER AROUND WHICH THE ENTIRE POWER SYSTEMS REVOLVES IS RESISTANCE OF THE MATERIAL. IF AN MATERIAL AS NATURE OF RRESTRICTING THE CURRENT THEN IT IS TERMED AS RESISTOR OTHERWISE CONDUCTOR. DEFINATION---THE PROPERTY OF OPPOSING ELECTRONS BY AN MATERIAL IS CALLED AS RESISTANCE, WHICH IS REPRESENTED IN TWO WAYS----EITHER IN TERMS OF RESISTIVITY, LENGTH,AREA OR IN TERMS OF VOLTAGE APPLIED AND CURRENT FLOWING THROUGH IT. PROCESS---TO AN MATERIAL WHEN EXTERNAL PRESSURE IS APPLIED( VOLTAGE) TILL THEN RANDOMLY MOVING ELECTRONS TENDS MOVE IN ONE PARTICULAR DIRECTION FROM CATHODE OT ANODE, DURING THIS TRAVEL ELECTRONS TENDS TO COLLIDE THE ATOMS OF MATERIAL THEIR BY LOOSING KINETIC ENERGY AND NOT REACHING THE ANODE, THIS IS CALLED AS RESISTANCE, AS NUMBER OF COLLISIONS INCREASES THE RESISTANCE PROPERTY OF MATERIAL ALSO INCRASES. THE MEASUREMENT OF RESISTANCE GOT VERY IMPORTANCE IN POWER SYSTEMS AS IT PLAYS KEY ROLE IN POWER SYSTEM OPERATION AND CONTROL. DEPENDING ON RANGE MEASUREMENT OF RESISTANCE IS CLASSIFIED INTO THREE TYPES--- 1. LOW RANGE RESISTANCE. 2. MEDIUM RANGE RESISTANCE. 3. HIGH RANGE RESISTANCE. LOW RANGE RESISTANCE: TO MEASURE LOW RANGE THE DOFFERENT METHODS ARE 1. VOLT-AMP METHOD 2. POTENTIOMETER 3. KE LVIN DOUBLE BRIDGE
WE SHALL STUDY DEEP INTO THESE METHODS AND CHOOSE WHICH METHOD IS BEST SUITABLE FOR MEASUREMENT OF RESISTANCE. EVERY METHODS GOT THEIR OWN ADVANTAGES, DISADVANTAGES AND LIMITATIONS. MEDIUM RANGE RESISTANCE: TO MEASURE MEDIUM RANGE THE DOFFERENT METHODS ARE 1. VOLT-AMP METHOD 2. SUBSTITUTION METHOD 3. WHEAT STONE BRIDGE. WE SHALL STUDY DEEP INTO THESE METHODS AND CHOOSE WHICH METHOD IS BEST SUITABLE FOR MEASUREMENT OF RESISTANCE. EVERY METHODS GOT THEIR OWN ADVANTAGES, DISADVANTAGES AND LIMITATIONS. HIGH RANGE RESISTANCE: TO MEASURE HIGH RANGE THE DOFFERENT METHODS ARE 1. VOLT-AMP METHOD 2. MEGA OHM BRIDGE 3. OHMMETER. 4. MEGGER. 5. LOSS OF CHARGE METHOD WE SHALL STUDY DEEP INTO THESE METHODS AND CHOOSE WHICH METHOD IS BEST SUITABLE FOR MEASUREMENT OF RESISTANCE. EVERY METHODS GOT THEIR OWN ADVANTAGES, DISADVANTAGES AND LIMITATIONS. THE DIFFERENT WAYS TO MEASURE RESISTANCE OF MATERIAL UNDER DIFFERENT CONDITIONS IN THE CHOOSEN ARE MEASURED WITH MOST PRECISIONEDLY. ALSO THE ERROR IN THE MEASUREMENT OF RESISTANCE USING VARIOUS METHODDS ARE THOROUGHLY ANALYSED HERE AND BEST METHOD IS SUGGESTED.
UNIT 7 THE OTHER TWO PARAMETERS WHICH RULE THE ELECTRICAL ENGINEERING ARE INDUCTOR AND CAPACITOR. INDUCTOR IS AN CONSTRUCTION OF WIRE IN THE TWISTED FORM EXHIBITING INDUCATNCE PROPERTY, THIS INDUCTOR ELEMENT GOT APPLICATIONS IN DESIGN OF MACHINES FOR GENERATION, FOR FILTERING, FOR STORING ENERGY ETC.THIS STORES ENERGY IN THE FORM OF MAGNETIC FIELD.INDUCTOR IS ASSOCIATED WITH STORING FACTOR. CAPACITOR IS THE CONSTRUCTION OF TWO PARALLEL PLATES SEPERATED BY INSULATION MEDIUM EXHIBITING PROPERTY OF CAPACITANCE, WHICH GOT APPLICATIONS IN POWER SYSTEM TRANSMISSION AND DISTRIBUTION. THIS STORES ENERGY IN THE FORM OF ELECTRIC FIELD.CAPACITOR IS ASSOCIATED WITH LOSS FACTOR. HENCE TO MEASURE INDUCTANCE AND CAPACITANCE AC BRIDGES ARE EVOVLED. AC BRIDGES CONSISTS OF FOUR ARMS, SOURCE AND DETECTOR. EACH ARM IS REPRESENTED WITH IMPEDANCE. SOURCE IS AN BRIDGE OSCILLATOR, POWER LINE ETC. MEASUREMENT OF UNKNOWN INDUCTANCE: CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM MAXWELL S BRIDGE ADAVTAGES AND DISADVANTAGES OF MAXWELL S BRIDGE CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM HAYS BRIDGE ADAVTAGES AND DISADVANTAGES OF HAYS BRIDGE
CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM ANDERSON S BRIDGE ADAVTAGES AND DISADVANTAGES OF ANDERSON S BRIDGE CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM OWEN S BRIDGE ADAVTAGES AND DISADVANTAGES OF OWEN S BRIDGE MEASUREMENT OF UNKNOWN CAPACITANCE: CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM DESAUTY S BRIDGE ADAVTAGES AND DISADVANTAGES OF DESAUTY S BRIDGE CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM WEIN S BRIDGE ADAVTAGES AND DISADVANTAGES OF WEIN S BRIDGE CONSTRUCTION AND DERIVATION OF ALONG WITTH THE PHASOR DIAGARM SCHERING BRIDGE ADAVTAGES AND DISADVANTAGES OF SCHERING BRIDGE THE AC BRIDGES GOT VERY MUCH IMPORATNCE IN MEASURING UNKNOWN PARAMETERS LIKE INDUCATNCE, CAPACIATNCE AND THEIR STORAGE, LOSS FACTOR. OTHER THAN USING RLC METERS TO MEASURE THESE PARAMETERS AC BRIDGES ARE COMPARISON METHODS WHICH GIVES VERY PRECISION VALUE. EVERY BRIDGE GOT THEIR OWN ADVANTAGES AND DISADVANTAGES TO OVERCOME THAT NEW BRIDGE IS EVOVLED.
UNIT 8 OTHER THAN MAJOR MEASURING DEVICES THEIR ARE OTHER DEVICES ALSO WHICH ARE USED OCCASIONALLY. OUT OF THAT WE ARE GOING TO DEAL WITH BALLASTIC GALVANOMETER AND FLUXMETER. HERE WE SHALL SEE THE DEFINATION OF BALLASTIC GALVANOMETER, CONSTRUCTION AND OPEARTION BALLASTIC GALVANOMETER, ADVANTAGES OF DISADVANTAGES OF BALLASTIC GALVANOMETER, EQUATION OF MOTION FOR BALLASTIC GALVANOMETER. LATER WE SHALL SEETHE CONSTRUCTION AND OPEARTION OF FLUX METER, ADVANTAGES OF DISADVANTAGES OF FLUX METER. COMPARISION BETWEEN BALLASTIC GALVANOMETER AND FLUXMETER.APPLICATIONS OF BALLASTIC GALVANOMETER AND FLUXMETER DETERMINATION OF B-H LOOP METHODS AC TESTING IRON LOSS OF BAR CORENSTRUCTION LOSS MEASUREMENT THEERE FOR THE IMPORATNCE OF BALLASTIC GALVANOMETER AND FLUXMETER IN POWER SYSTEMS ARE STUDIED, AND THEIR IMPORTANCES ARE COMPARED.