Electrical Machines And Instruments

Electrical Machines And Instruments

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Measuring InstrumentsPrinciple of Permanent Magnet Moving Coil (PMMC), Moving Iron Instruments, Ammeters a Voltmeters, Operating Principles of the Electrodynamometer Instruments. Wattmeter, Energy meter, Electrostatic Instruments, Rectifier type Instruments, Extension of Ranges of Voltmeters and Ammeters. Principle of Power Factor a Frequency meter. Use of Current a Potential Transformers. Measurement of R, L, and CMeasurement of low, medium a high resistances Wheatstone a Kelvin bridge, Ohmmeter, Megger. A.C. bridge circuits for measurement of inductance a capacitance-Maxwell s, Hay s a Anderson s bridge, Schering bridge.PotentiometersPrinciples of D.C a A.C. Potentiometers a their applications.Magnetic Properties of MaterialsThe magnetic dipole movement, diamagnetism. The origin of permanent magnetic dipoles in matter, Paramagnetism, Ferromagnetism.D.C. MotorsPrinciples of working, E.M.F. equation, back EMF, torque equations, methods of excitation, characteristics of D.C. shunt, series a compound motors, speed torque characteristic of D.C. motors, starters, principles of speed control. Three Phase Induction MotorsRotating magnetic field, construction a principle of operation, slip, rotor frequency, development of equivalent circuit, torque equation, maximum torque, torque speed characteristics, speed control. Starting methods, motor ratings.Stepper MotorPrinciple of working, characteristics a applications.Its armature resistance is 0.27 ohms. Calculate the value of the starting resistance necessary to limit the starting current to 1.5 times the rated current of the motor. Neglect the shunt field current. ( Ans. : 4 ohms ) 18. Armature resistance of d.c.anbsp;...

Title:Electrical Machines And Instruments
Author:A.V.Bakshi U.A.Bakshi
Publisher:Technical Publications - 2007-01-01


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