×
Failure will never overtake me if my determination to succeed is strong enough.
--Your friends at LectureNotes
Close

Electrical and Electronics Instrumentation

by Jntu HeroesJntu Heroes
Type: NoteOffline Downloads: 76Views: 1954Uploaded: 11 months ago

Share it with your friends

Suggested Materials

Leave your Comments

Contributors

Jntu Heroes
Jntu Heroes
Electrical and Electronics Instrumentation Materials & Notes UNIT 1 INTRODUCTION: “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.
DISCRIPTION: 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. CONCLUSION: 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 INTRODUCTION: 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. DISCRIPTION: 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. CONCLUSION: 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.

Lecture Notes