JNTU B.Tech II ELECTRICAL ENGINEERING Previous Question Paper (April/May - 2023 - R16)

What is Kirchhoff’s current law?

Enumerate advantages of Moving Iron instrument.

What is average and RMS value of alternating quantity?

Give the quality factor in terms of Bandwidth.

List types of dc motors.

Draw the characteristics of a d.c. shunt generator.

What is a transformer? List some of the important functions it fulfills?

How is a rotating magnetic field in a three phase induction motor obtained?

What is open-circuit test of an alternator?

What is synchronous reactance and synchronous impedance in alternator?

Explain the concept of star-delta and delta-star transformations.

Describe the working principle of moving coil instrument with neat sketch.

A 100 W, 250 V bulb is put in series with a 40 W, 250 V bulb across a 500V supply. What will be the power consumed by each bulb? Will such a combination work?

Find the equivalent resistance between the terminals X and Y in the circuit as shown in the figure.

A parallel circuit comprises of two branches having impedances Z1 =(10+j30) Ω and Z2 =(6-j8) Ω. The total current taken is 15A. What is the power taken by each branch and the total power consumed by the circuit?

Three impedances each of (3-j4) Ω is connected in delta connection across a 3-φ, 230V balanced supply. Calculate the line and phase currents in the ∆ connected load and the power delivered to the load?

Bring out the differences between series and parallel resonance.

A coil of inductance 2H and resistance of 10Ω in series with condenser ‘C’ is supplied at constant voltage from variable frequency. If a maximum current is 10A at 75Hz, find the value of C and also determine the frequency when the current is 5A.

What are the factors that control the speed of d.c motors? Explain any two methods for controlling the speed of shunt motors.

A 4 pole, DC motor takes an armature current of 50 A. The armature has 480 lap connected conductors. The flux per pole is 20 mwb. Calculate the gross torque developed by the motor.

Why is a starter necessary for a motor? What are the functions of ‘no-volt release’ and ‘over load release’ in a starter?

An 8-pole D.C shunt generator with 788 wave connected conductors and running at 500 r.p.m. supplies a load of 12.5 Ω at terminal voltage of 250 V. The armature and field resistances of 0.24 Ω and 250 Ω respectively. Find (i) Armature current (ii) Induced emf (iii) Flux/pole.

Derive an expression for induced emf in a transformer in terms of frequency the maximum value of flux, and the number of turns on the winding.

The primary winding of a 50 HZ single phase transformer has 480 turns and is fed from 6400 V supply. The secondary winding has 20 turns. Find the peak value of flux in the core and the secondary Voltage.

Draw the slip-Torque characteristics of an Induction Motor. Explain it clearly.

The primary and secondary winding resistances of a 40 kVA, 6600/250V single phase transformer are 10 Ω and 0.02 Ω respectively. The equivalent leakage reactance as referred to the primary winding is 35 Ω. Find the full load regulation for load power factors of (i) unity (ii) 0.8 lagging (iii) 0.8 leading.

Why salient pole alternators have large diameters and small core lengths?

A 2000V, 1-φ alternator was tested on open circuit and short circuit. The details of which are as follows. A field current of 2.5 A produced a short circuit current of 100 A. With open circuit, the same field current generated an e.m.f of 500V. The effective resistance of the armature is 0.8 ohm. Calculate the regulation at full load current of 100A. (i) At a power factor of 0.65 leading (ii) At a power factor of 0.65 leading

Explain in brief principle of operation of alternators.

Explain why synchronous impedance method of computing voltage regulation leads to a pessimistic value at lagging power factor loads?