Electrical Measurements Syllabus for JNTU
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY,
III Year B.Tech EEE I-Sem T P C
4+1* 0 4
Electrical measurements course introduces the basic principles of all measuring instruments. It also deals
with the measurement of RLC parameters voltage, current Power factor, power, energy and magnetic
UNIT-I 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 Voltmeterselectrometer
type and attracted disc type – Extension of range of E.S. Voltmeters.
UNIT –II Instrument transformers
CT and PT – Ratio and phase angle errors – design considerations Type of P.F. Meters – dynamometer
and moving iron type – 1-ph and 3-ph meters – Frequency meters – resonance type and Weston type –
UNIT –IIIMeasurement of Power
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
UNIT –IV Measurement of Energy
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 – trivector meter, maximum
UNIT – V Potentiometers
Principle and operation of D.C. Crompton’s potentiometer – standardization – Measurement of unknown
resistance, current, voltage.
A.C. Potentiometers: polar and coordinate types standardization – applications.
UNIT – VI Resistance Measurements
Method of measuring low, medium and high resistance – sensitivity of Wheatstone’s bridge – Carey
Foster’s bridge, Kelvin’s double bridge for measuring low resistance, measurement of high resistance –
loss of charge method.
UNIT –VII A.C. Bridges
Measurement of inductance, Quality Factor – Maxwell’s bridge, Hay’s bridge, Anderson’s bridge, Owen’s
bridge. Measurement of capacitance and loss angle – Desauty bridge. Wien’s bridge – Schering Bridge.
UNIT – V III
Ballistic galvanometer – equation of motion – flux meter – constructional details, comparison with ballistic
galvanometer. Determination of B-H Loop methods of reversals six point method – A.C. testing – Iron loss
of bar samples– core loss measurements by bridges and potentiometers.
1. Electrical Measurements and measuring Instruments – by E.W. Golding and F.C. Widdis, fifth
Edition, Wheeler Publishing.
2. Electrical & Electronic Measurement & Instruments by A.K.Sawhney Dhanpat Rai & Co.
1. Electrical Measurements – by Buckingham and Price, Prentice – Hall
2. Electrical Measurements by Harris.
3. Electrical Measurements: Fundamentals, Concepts, Applications – by Reissland, M.U, New Age
International (P) Limited, Publishers.