JNTU
JNTU B.Tech III SWITCH GEAR AND PROTECTION Previous Question Paper (February - 2023 - R16)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Give different types of circuit breakers.
Answer
Circuit breakers are primarily classified based on the medium used for arc extinction: Oil circuit breakers (bulk oil and minimum oil), Air-break circuit breakers, Air-blast circuit breakers, Sulfur hexafluoride (SF6) circuit breakers, and Vacuum circuit breakers.
Explain briefly the concept of auto reclosing in circuit breakers.
Answer
Auto-reclosing is a feature where the circuit breaker automatically recloses after a predetermined time following a trip caused by a transient fault. Since most faults on overhead lines are temporary, this process restores power supply quickly without manual intervention, improving system reliability and stability.
Classify the electromagnetic relays based on their construction.
Answer
Sign in to view the complete answer paper.
Classify various types of static relays.
Answer
Sign in to view the complete answer paper.
Classify various protection schemes applied to feeder protection.
Answer
Sign in to view the complete answer paper.
Give the reasons for failure of bus bars.
Answer
Sign in to view the complete answer paper.
What is grounding?
Answer
Sign in to view the complete answer paper.
What is arcing grounds? Explain.
Answer
Sign in to view the complete answer paper.
What are lightning over voltages?
Answer
Sign in to view the complete answer paper.
List various types of over voltage protection schemes.
Answer
Sign in to view the complete answer paper.
Part B
Briefly explain the elementary principles of arc interruption.
Answer
Sign in to view the complete answer paper.
Differentiate Air blast and SF6 circuit breakers.
Answer
Sign in to view the complete answer paper.
Discuss the current interruption and control of arc in Vacuum circuit breakers.
Answer
Sign in to view the complete answer paper.
Determine the RRRV for the circuit breaker installed on a 400kV, three phase, 50Hz system. The respective data is obtained during a short circuit when grounded fault occurred. Recovery voltage=0.97 of full line value, power factor of a fault is 0.45, natural frequency for symmetrical breaking current is 16kHz.
Answer
Sign in to view the complete answer paper.
Discuss the working of Induction cup relay with a neat circuit diagram.
Answer
Sign in to view the complete answer paper.
Give the differences between impedance relay, reactance relay and mho relay schemes based on their working.
Answer
Sign in to view the complete answer paper.
What is a under voltage relay explain its working with help of neat diagram?
Answer
Sign in to view the complete answer paper.
Explain the three zone distance relay using impedance relays.
Answer
Sign in to view the complete answer paper.
What is the relay added for the protection of transformer? Give its merits and demerits.
Answer
Sign in to view the complete answer paper.
Write a short note on differential protection in bus bars.
Answer
Sign in to view the complete answer paper.
Give the reasons for inter turn fault in generators and method to protect from it.
Answer
Sign in to view the complete answer paper.
Discuss about the protection of generators against stator faults and abnormal condition.
Answer
Sign in to view the complete answer paper.
Discuss the impacts of ungrounded neutral on system performance.
Answer
Sign in to view the complete answer paper.
Explain briefly about resistance grounding. Give its merits and demerits.
Answer
Sign in to view the complete answer paper.
Differentiate various types of grounding methods based on applications.
Answer
Sign in to view the complete answer paper.
Explain various methods of reducing the Switching over voltages.
Answer
Sign in to view the complete answer paper.
What is a surge arrester? Differentiate between a surge absorber and a surge arrester.
Answer
Sign in to view the complete answer paper.
Describe the different types of overvoltage’s and mention their causes of initiation.
Answer
Sign in to view the complete answer paper.
Define: i) BIL ii) Impulse Ratio iii) Standard Impulse Test Wave.
Answer
Sign in to view the complete answer paper.