JNTU B.Tech I Year BASIC ELECTRICAL ENGINEERING Previous Question Paper (May - 2019 - R18)

Write short notes on voltage source and current source.

Define average value of a sinusoidal quantity.

What is practical transformer?

Define slip.

List out the types of wires.

State Norton’s theorem.

Show that power dissipated by a pure capacitor excited by a sinusoidal source is zero.

Write short notes on auto transformer.

Write short notes on salient pole rotor of a 3-ϕ synchronous generator.

What is the significance of earthing?

Explain in detail the passive elements.

By using Thevenin’s theorem shown in figure, find the current in 6Ω resistor.

State and explain Superposition theorem by taking one example.

Three resistors: R₁=5Ω, R₂=10Ω, R₃=15Ω are connected in parallel across a DC voltage source: 100V. Find the currents I₁, I₂, I₃ through R₁, R₂, R₃ and the total current supplied by 100V source.

Show that the resonant frequency ω₀ of an RLC series circuit is the geometric mean of ω₁ and ω₂, the lower and upper half power frequencies respectively.

A circuit consisting of three branches, Z₂ is in parallel with Z₃ the combination is in series with Z₁ having the values Z₁=10+j30, Z₂=5+j10 and Z₃=4-j16 connected across single phase, 100 V, 50 Hz supply. Find i) I₁, I₂ and I₃ ii) V₁ and V₂

Derive the expression for RMS value of alternating current wave I = I_m Sin ωt.

A coil takes a current of 1 A at 0.6 lagging power factor from a 220 V, 60 Hz single phase source. If the coil is modeled by a series RL circuit find i) The complex power in the coil and ii) The values of R and L.

Draw and derive the equivalent circuit parameters of single phase transformers.

A single phase transformer working at unity power factor has an efficiency of 90% at both one half load and at the full load of 500 W. Determine the efficiency at 75% of full load.

Define and explain efficiency and regulation of a transformer.

A 100 kVA, 1000/10000 V, 50 Hz, Single phase transformer has an iron loss of 1100 W. The copper loss with 5 A in the high voltage winding is 400 W. Calculate the efficiency at 25 %, 0.8 Power factor. The output terminal voltage being maintained at 10000 V.

Explain the slip-torque characteristics of 3-phase induction motor.

Explain the principle and operation of 1-phase induction motor.

Explain the working principles of Synchronous generator.

A 6 pole, 3-ø induction motor runs at 1140 rpm on full load when supplied from a 60Hz supply. Determine the synchronous speed and slip at full load.