Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech I BASIC ELECTRICAL ENGINEERING Previous Question Paper (January - 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
State and explain superposition theorem.
Answer
The Superposition Theorem states that in any linear, bilateral network containing two or more independent sources, the response (voltage or current) in any branch is equal to the algebraic sum of the individual responses caused by each independent source acting alone, while all other independent sources are replaced by their internal impedances.
The steps to apply the theorem are:
- Retain one independent source and replace all other independent voltage sources with a short circuit (0 V) and all independent current sources with an open circuit (0 A).
- Calculate the response in the desired branch due to the single active source.
- Repeat this process for each independent source present in the circuit.
- Algebraically add all the individual responses to obtain the total response, taking care of the assumed directions of currents or polarities of voltages.
Using superposition theorem, find voltage V in the circuit shown below figure.
Answer
Since the circuit diagram was not provided in the prompt, the general procedure to find voltage V using the superposition theorem is as follows:
- Identify all independent sources (e.g., V1, I1).
- Case 1: Consider only the first source. Replace other voltage sources with short circuits and current sources with open circuits. Calculate the partial voltage V' across the specified terminals using series-parallel reduction or nodal analysis.
- Case 2: Consider only the second source. Replace the first source with its internal impedance (short or open) and calculate the partial voltage V'' across the same terminals.
- Repeat for any additional sources to find V''', etc.
- Find the total voltage V by summing the individual components: V = V' + V'' + V''' + ...
The final value of V is obtained by maintaining consistent reference polarities for each individual calculation.
State and explain Thevenin’s theorem with a suitable example.
Answer
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What is a phasor? Explain the benefits of phasor representation of sinusoidal signals.
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Define resonance? Explain the phenomenon in series RLC circuit.
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A balanced RYB sequence star connected source with VRN = 120∠10° is connected to a star connected balanced load (4+j4) Ω per phase. Calculate the phase and line currents.
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What are the features of an ideal transformer? Explain in detail.
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What is an auto transformer? Explain its working.
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Obtain the equivalent circuit of a single phase transformer.
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What is rotating magnetic field? What is its significance? How is it produced?
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Explain about different types of batteries.
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Write short notes on MCB and MCCB.
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