Selected Problems (long and Medium) For REE-101

Selected Problems (long and Medium) For REE-101

UNIT-I

Q:-1 State and prove maximum power transfer theorem.

Q:-2 What is the criterion for star – delta transformation? Develop the relationship for delta to star and star to delta transformation.

Q:-3 Draw V-I characteristic of voltage and current sources. Explain source transformation theory in a circuit.

UNIT-II

Q:-1 What are the causes of low power factor in supply system? Discuss its effect & how power factor can be improved?

Q:-2 Derive resonance condition in series circuit. Also derive the expression for Bandwidth.

Q:-3 Derive resonance condition in parallel circuit. Also derive the Quality Factor of the Parallel RLC Circuit at resonance.

UNIT-III

Q:-1 Derive the relation between line voltage and phase voltage in three-phase delta connected circuit..

Q:-2 Derive the relation between line voltage and phase voltage in three-phase star connected circuit. Also derive the expression for power.

Q:-3  With the help of connection diagram and the related phasor diagram show that W1 +  W2 gives the total 3-phase power in a two wattmeter method of power measurement and determine the active three phase power and load power factor.

Q:-4 Draw and explain the working of attraction type moving iron instrument.

Q:-5 Derive the torque equation and explain the working of repulsion type moving iron instrument.

Q:-6 Explain the PMMC instrument. Also derive the expression for deflected torque.

Q:-7 Explain the construction and working of Electrodynamics type instrument with diagram.

UNIT-IV

Q:-1 What is B-H curve? Also explain the hysteresis and eddy current loss.

Q:-2 Explain the analogy between electric and magnetic circuit with AC excitation.

Q:-3 Explain the working of a transformer with the derivation of the emf equation for a transformer. Also discuss the losses in the transformer.

Q:-4 Derive the condition for maximum efficiency for a Transformer.

Q:-5Explain single phase auto transformer and give its two applications.

UNIT-V

Q:-1 Derive the expression for EMF equation for a DC machine.

Q:-2 Draw the characteristics of DC series motors.

Q:-3 Derive the expression of torque for dc motor. Also discuss the characteristics of dc shunt motor.

Q:-4 Why a three phase synchronous motor is not self starting? Discuss use of damper winding for starting a synchronous motor.

Q:-5 Explain the slip-torque characteristics of three phase induction motor.

Q:-6 Explain with the help of diagrams, how a rotating field is produced in the air gap of a  three-phase induction motor.

Q:-7 Using double field revolving theory, explain why single phase induction motor is not self starting? Describe capacitor start- capacitor run method for starting single phase induction motor and give any two application of such motor.