Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II Year ELECTRICAL ENGINEERING Previous Question Paper (November/December - 2018 - R13)
Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
Define the KCL and KVL.
Answer
Kirchhoff's Current Law (KCL) states that the algebraic sum of currents meeting at any junction or node in an electrical circuit is zero. Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop in a circuit is zero.
Define self and mutual inductances.
Answer
Self-inductance is the property of a coil to oppose any change in current flowing through it by inducing an electromotive force (EMF) within itself. Mutual inductance is the property by which a change in current in one coil induces an EMF in an adjacent, magnetically coupled coil.
Define i) average value ii) RMS value of alternating quantity.
Answer
Sign in to view the complete answer paper.
A coil of inductance 100mH and negligible resistance is connected in series with a resistor of 12.5 ohm and a capacitor of 2.5 µf. The supply voltage is 250 V with variable frequency. Find the resonant frequency?
Answer
Sign in to view the complete answer paper.
What is the principle of DC motor.
Answer
Sign in to view the complete answer paper.
What are different types of dc motors?
Answer
Sign in to view the complete answer paper.
What is working principle of single phase transformer.
Answer
Sign in to view the complete answer paper.
What are the different types of induction motors? Give their applications.
Answer
Sign in to view the complete answer paper.
Define the voltage regulation of alternator.
Answer
Sign in to view the complete answer paper.
Mention different types of methods used to calculate voltage regulation of an alternators.
Answer
Sign in to view the complete answer paper.
Part B
Define Len’z law.
Answer
Sign in to view the complete answer paper.
Assume there are 10 light bulbs that can be connected in parallel having resistance 10 ohm each find the equivalent resistance of circuit. If connected in series what is equivalent resistance?
Answer
Sign in to view the complete answer paper.
Explain constructional details of a typical PMMC instruments with neat diagram.
Answer
Sign in to view the complete answer paper.
The circuit having the values of L=5H, C=2mF connected in series with resistance, what is the resonance frequency if a)R=10 ohm, b)20 ohm c)50 ohm and conclude what is the effect of resonance if resistance increase?
Answer
Sign in to view the complete answer paper.
Define rms value of a periodic wave form.
Answer
Sign in to view the complete answer paper.
Determine the rms value of the current waveform shown in figure. The current is passed through a 2 ohm resistor, find the average power absorbed by the resistor.
Answer
Sign in to view the complete answer paper.
Derive the EMF equation for DC generator.
Answer
Sign in to view the complete answer paper.
The power input to a 230V dc shunt motor is 8.477 kW. The field resistance is 230 ohm and armature resistance is 0.28 ohm. Find armature current and back emf.
Answer
Sign in to view the complete answer paper.
How is swimburne test conducted on a dc machine? How can the efficiency be determined from the results of this test when the machine works as: i) Motor ii) Generator.
Answer
Sign in to view the complete answer paper.
Why can’t swimburne test be applied to series machines.
Answer
Sign in to view the complete answer paper.
Derive the equation for induced emf in a transformer.
Answer
Sign in to view the complete answer paper.
A single-phase transformer is connected to a 230 V, 50 Hz supply. The secondary number of turns is 1500 and the maximum flux in the core is 2.07 mWb. Determine the secondary induced voltage?
Answer
Sign in to view the complete answer paper.
Explain principle and operation of squirrel cage induction motor.
Answer
Sign in to view the complete answer paper.
A 12-pole 3-phase alternator is couples to an engine running at 500 rpm. It supplies a 3-phase induction motor having a full-load speed of 1440 rpm. Find the percentage slip and number of poles of motor?
Answer
Sign in to view the complete answer paper.
Discuss the synchronous impedance and mmf methods of calculating regulation of an alternator. Why do these methods give different results?
Answer
Sign in to view the complete answer paper.
A 3-phase star connected alternator is rated at 1600KVA 13.5kV. The effective armature resistance and synchronous reactance are 1.5 ohms and 30 ohm per phase, respectively. Find regulation for a load of 1280 kW, rates voltage and power factor of (a) 0.6 leading, (b)unity, (c) 0.6 lagging.
Answer
Sign in to view the complete answer paper.