Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II BASIC ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (October - 2020 - R18)
Answer any five questions. All questions carry equal marks.
Main
Explain the star-delta and delta-star transformation?
Answer
Star-Delta and Delta-Star transformations are used to simplify complex resistive networks that cannot be reduced by simple series or parallel combinations. A Star (Y) network consists of three resistors connected to a common node, while a Delta (Δ) network consists of three resistors connected in a closed loop.
To convert from Delta to Star (given resistors Rab, Rbc, Rca), the equivalent star resistors are calculated as:
To convert from Star to Delta (given resistors Ra, Rb, Rc), the equivalent delta resistors are calculated as:
Find the equivalent resistance of the circuit shown in below figure.
Answer
Since the figure was not provided in the prompt, the general procedure to find the equivalent resistance is as follows:
- Identify if any resistors are in simple series or parallel combinations and simplify them first.
- If the circuit contains a bridge or complex mesh structure, identify a delta or star configuration within the network.
- Apply the transformation formulas provided in part (a) to convert the delta section to star or vice-versa.
- Redraw the circuit with the new equivalent resistors.
- Combine the resulting series and parallel branches to find the total equivalent resistance between the specified terminals.
What is meant by power factor of an ac circuit? What is its minimum and maximum value.
Answer
Sign in to view the complete answer paper.
What are the advantages of the three phase system over single phase system?
Answer
Sign in to view the complete answer paper.
Explain the construction and working principle of a miniature circuit breaker.
Answer
Sign in to view the complete answer paper.
State the importance characteristics of batteries. Also state the difference between primary and secondary batteries.
Answer
Sign in to view the complete answer paper.
Deduce the emf equation of a transformer.
Answer
Sign in to view the complete answer paper.
A single phase, 250kVA, 11 kV/415V, 50 Hz transformer with 80 tuns on the secondary is working on full load. Calculate (i) the approximate values of the primary and secondary currents, (ii) the approximate number of primary turns and (iii) the maximum value of flux.
Answer
Sign in to view the complete answer paper.
Explain the construction features of a AC generator.
Answer
Sign in to view the complete answer paper.
A 4 pole, wave connected armature in a dc generator has 51 slots with 12 conductors per slot. It is driven at 900 rpm. If the useful flux per pole is 25 mWb, calculate the value of the generated emf.
Answer
Sign in to view the complete answer paper.
Describe the operation of full wave bridge rectifier with neat circuit diagram and wave forms.
Answer
Sign in to view the complete answer paper.
What are the types of filters? Mention its uses.
Answer
Sign in to view the complete answer paper.
Explain the working principle of an n-p-n transistor.
Answer
Sign in to view the complete answer paper.
Explain with the help of a circuit diagram of a transistor as an amplifier.
Answer
Sign in to view the complete answer paper.