Electrical Measurements & Instrumentation

Measurement system, Characteristics of instruments, Methods of measurement, Errors in Measurement & Measurement standards, Classification of Instrument – deflecting, controlling and damping torques – Ammeters and Voltmeters – PMMC, moving iron, Electrostatic, induction type instruments – expression for the deflecting torque and control torque – Errors and compensations, extension of range of instruments.

Types of watt meters, Single phase dynamometer & induction type wattmeter, Expression for deflecting and control torques. Measurement of active and reactive power in balanced and unbalanced three phase systems, theory and operation of single & three phase induction type energy meter, power factor meter & analog frequency meter.

Principle and operation of D.C. Crompton’s potentiometer standardization – Measurement of unknown resistance, current, voltage. A.C. Potentiometers. Method of measuring low, medium and high resistance – sensitivity of wheat-stone’s bridge – Kelvin’s double bridge for measuring low resistance. Measurement of inductance-Maxwell’s bridge, Hay’s bridge, Anderson’s bridge, Owens’s bridge. Measurement of capacitance and loss angle – Desauty’s bridge, Wien’s bridge, Schering Bridge.

CT and PT Construction and working, Ratio and phase angle errors, testing and design considerations. Electronic Voltmeter- Ammeter, Multimeter, Wattmeter & Energy meter, Principle of CRO, Time, Frequency and phase angle measurements using CRO. Spectrum & Wave analyzer and Digital Voltmeter.

Definition of transducers, Classification of transducers, Advantages of Electrical transducers, Characteristics and choice of transducers; Principal operation of LVDT and capacitor transducers, LVDT Applications, Strain and its principle of operation, gauge factor, Thermistors, Thermocouples, Piezo electric transducers, photovoltaic, photo conductive cells, and photo diodes.