JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Pre-requisite

Nil

Course Objectives

Objectives of this course are:

• to introduce the basic principles of all measuring instruments
• to deal with the measurement of voltage, current Power factor, power, energy and magnetic measurements.

Course Outcomes

After this course, the student

• gets a thorough knowledge on, different types of measuring instruments their construction operation and characteristics
• measurements of electrical quantities through potentiometers, instrument transformers, watt meters, energy meters, DC bridges and AC bridges
• To understand the operation of different types of transducers.
• To understand the measurement of non-electrical quantities like velocity, acceleration, temperature etc.
• Applies the above concepts to real-world electrical and electronics problems and applications.

UNIT - I

Introduction to Measuring Instruments: Classification – deflecting, control and damping torques – Ammeters and Voltmeters – PMMC, moving iron type instruments – expression for the deflecting torque and control torque – Errors and compensations, extension of range using shunts and series resistance. Electrostatic Voltmeters - electrometer type and attracted disc type – extension of range of E.S. Voltmeters.

UNIT - II

Potentiometers & Instrument Transformers: Principle and operation of D.C. Crompton’s potentiometer – standardization – Measurement of unknown resistance, current, voltage. A.C. Potentiometers: polar and coordinate type’s standardization – applications. CT and PT – Ratio and phase angle errors

UNIT - III

Measurement of Power & Energy: Single phase dynamometer wattmeter, LPF and UPF, Double element and three element dynamometer wattmeter, expression for deflecting and control torques – Extension of range of wattmeter using instrument transformers – Measurement of active and reactive powers in balanced and unbalanced systems. Single phase induction type energy meter – driving and braking torques – errors and compensations – testing by phantom loading using R.S.S. meter. Three phase energy meter – tri-vector meter, maximum demand meters.

UNIT - IV

DC & AC Bridges: Method of measuring low, medium and high resistance – sensitivity of Wheat-stone’s bridge – Carey Foster’s bridge, Kelvin’s double bridge for measuring low resistance, measurement of high resistance – loss of charge method. Measurement of inductance - Maxwell’s bridge, Hay’s bridge, Anderson’s bridge - Owen’s bridge. Measurement of capacitance and loss angle – Desauty’s Bridge - Wien’s bridge – Schering Bridge.

UNIT - V

Transducers: Definition of transducers, Classification of transducers, Advantages of Electrical transducers, Characteristics and choice of transducers; Principle operation of LVDT and capacitor transducers; LVDT Applications, Strain gauge and its principle of operation, gauge factor, Thermistors, Thermocouples, Piezo electric transducers, photovoltaic, photo conductive cells, photo diodes. Measurement of Non-Electrical Quantities: Measurement of strain, Gauge sensitivity, Displacement, Velocity, Angular Velocity, Acceleration, Force, Torque, Temperature, Pressure, Vacuum, Flow and Liquid level.

TEXT BOOKS:

• 1. Electrical and Electronic Measurements and Instrumentation, R. K. Rajput, S. Chand & Company Ltd.
• 2. Electrical Measuring Instruments and Measurements, S. C. Bhargava, BS Publications.

REFERENCE BOOKS:

• 1. Electrical & Electronic Measurement & Instruments, A.K.SawhneyDhanpat Rai & Co. Publications.
• 2. Electrical and Electronic Measurements, G. K. Banerjee, PHI Learning Pvt. Ltd.
• 3. Electrical Measurements and Measuring Instruments, Golding and Widdis, Reem Publications.
• 4. Electrical Measurements, Buckingham and Price, Prentice – Hall
• 5. Electrical Measurements: Fundamentals, Concepts, Applications, Reissland, M.U, New Age International (P) Limited, Publishers.
• 6. Electrical Measurements and measuring Instruments, E.W. Golding and F.C. Widdis, fifth Edition, Wheeler Publishing.