JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year FUNDAMENTALS OF ELECTRICAL ENGINEERING Previous Question Paper (November/December - 2017 - R13)

List the differences between independent and dependent sources?

State and explain faraday’s laws of electromagnetic induction?

Explain the concept of resonance.

A coil has a resistance of 4Ω and an inductance of 9.55 mH. Calculate the reactance, the impedance, and the current taken from a 240V, 50 Hz supply.

State tellegen’s theorem.

State and explain reciprocity theorem.

Explain the principle of operation of DC motor.

Explain the classification of DC generators based on excitation.

What are different losses of single phase transformer?

Why Single phase induction motor is not self starting. Explain?

Explain Star-Delta transformation.

A silicon iron ring is wound with 800 turns, the ring having a mean diameter of 120 mm and a cross-sectional area of 400 mm². If when carrying a current of 0.5A the relative permeability is found to be 3000, calculate (i) the self-inductance of the coil, (ii) the induced e.m.f. if the current is reduced to zero in 80 ms.

In the circuit shown in Figure 1, determine the power absorbed by the 12Ω resistor.

A closed magnetic circuit of cast steel contains a 6 cm long path of cross-sectional area 1 cm² and a 2 cm path of cross-sectional area 0.5 cm². A coil of 200 turns is wound around the 6 cm length of the circuit and a current of 0.4 A flows. Determine the flux density in the 2 cm path, if the relative permeability of the cast steel is 750.

Find the rms value of the current waveform of Figure 2. If the current flows through a 9 Ω resistor, calculate the average power absorbed by the resistor.

A coil of resistance 5 Ω and inductance 120mH in series with a 100 μF capacitor is connected to a 300V, 50 Hz supply. Calculate (i) the current flowing, (ii) the phase difference between the supply voltage and current, (iii) the voltage across the coil and (iv) the voltage across the capacitor.

Define the following with respect to sinusoidal quantity: (i) RMS Value (ii) Average Value (iii) Form factor (iv) Peak factor.

A coil of negligible resistance and inductance 100 mH is connected in series with a capacitance of 2 μF and a resistance of 10 Ω across a 50V, variable frequency supply. Determine (i) the resonant frequency, (ii) the current at resonance, (iii) the voltages across the coil and the capacitor at resonance, and (iv) the Q-factor of the circuit.

State and explain superposition theorem with an example.

Find the maximum power that can be delivered to the resistor R in the circuit shown in figure 3.

State and explain compensation theorem with an example.

Using superposition, find the current I through the 6-Ω resistor shown in the circuit (figure 4).

Derive the expression for Generated EMF of DC generator.

A 4 pole DC generator with a shunt field resistance of 100 Ω and armature resistance of 1 Ω has 378 wave connected conductors in its armature. The flux per pole is 0.02 Wb. If a load resistance of 10 Ω is connected across the Armature terminals and the generator is driven at 1000 rpm, calculate the power absorbed by the load.

A six-pole lap-wound motor is connected to a 240V d.c. supply. The armature has 450 conductors and a resistance of 1Ω. The flux per pole is 20 m Wb. Calculate (i) the speed and (ii) the torque developed when the armature current is 40A.

Draw and explain load characteristics of different dc generators.

Define regulation of a transformer.

A 6 kVA, 100V/500V, single-phase transformer has a secondary terminal voltage of 487.5 volts when loaded. Determine the regulation of the transformer.

Explain the construction of single phase synchronous generator.

With the help of ‘double revolving field theory’ explain the operation of single phase Induction motor.

Draw and explain the equivalent circuit of single phase transformer.