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Unit1.
Measuring Instruments: Moving coil, moving iron, electrodynamic and
induction instrumentsconstruction, operation, torque equation and errors.
Applications of instruments for measurement of current, voltage,
single-phase power and single-phase energy. Errors in wattmeter and energy
meter and their compensation and adjustment. Testing and calibration of
single-phase energy meter by phantom loading.
Unit2. Polyphase Metering: Blondel's Theorem for n-phase, p-wire
system. Measurement of power and reactive kVA in 3-phase balanced and
unbalanced systems: One-wattmeter, two-wattmeter and three-wattmeter
methods. 3-phase induction type energy meter. Instrument Transformers:
Construction and operation of current and potential transformers. Ratio
and phase angle errors and their minimization. Effect of variation of
power factor, secondary burden and frequency on errors. Testing of CTs and
PTs. Applications of CTs and PTs for the measurement of current, voltage,
power and energy.
Unit3. Potentiometers: Construction, operation and standardization
of DC potentiometers – slide wire and Crompton potentiometers. Use of
potentiometer for measurement of resistance and voltmeter and ammeter
calibrations. Volt ratio boxes. Construction, operation and
standardization of AC potentiometer – in-phase and quadrature
potentiometers. Applications of AC potentiometers.
Unit4. Measurement of Resistances: Classification of resistance.
Measurement of medium resistances – ammeter and voltmeter method,
substitution method, Wheatstone bridge method. Measurement of low
resistances – Potentiometer method and Kelvin's double bridge method.
Measurement of high resistance: Price's Guard-wire method. Measurement of
earth resistance.
Unit5. AC Bridges: Generalized treatment of four-arm AC bridges.
Sources and detectors. Maxwell's bridge, Hay's bridge and Anderson bridge
for self-inductance measurement. Heaviside's bridge for mutual inductance
measurement. De Sauty Bridge for capacitance measurement. Wien's bridge
for capacitance and frequency measurements. Sources of error in bridge
measurements and precautions. Screening of bridge components. Wagner earth
device.
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