Important RGPV Question
EX-701 Power System Protection
VII Sem, EX
UNIT-I Fault Analysis
Q.1 what are the different types of faults in power systems and how do they affect system stability? (RGPV Dec 2024)
Q.2 Describe the types, construction and application of current – linking reactors. (RGPV Dec 2024)
Q.3 Explain why fault currents are more than load currents? What is meant by fault level or fault MVA? Explain. (RGPV Nov 2023)
Q.4 Distinguish between symmetrical and unsymmetrical faults occurring on a power system and draw the sequence network diagram for the following types of faults at the terminals of an unloaded generator. (RGPV Nov 2023)
- Three phase short circuit
- Single line to ground fault
Q.5 Write of short note on -Line to ground fault. (RGPV Nov 2023)
Q.6 Describe the common faults in alternators and the protection schemes used to safeguard them. (RGPV Dec 2024)
Q.7 In a short circuit test on a 3 pole, 110 kV circuit breaker, power factor of the fault was 0.4, the recovery voltage was 0.95 times full line value. The breaking current was symmetrical. The frequency of oscillation of restriking voltage was 15000c/s. estimate the average rate of rise of restriking voltage. The neutral is grounded and the fault involves earth. (RGPV Nov 2022)
Q.8 A generator of negligible resistance having 1.0 per unit voltage behind transient reactance is subjected to different types of faults. Such as for 3 phase fault the resulting fault current in per unit is 3.33 for line to line fault it is 2.23 and for line to ground fault it is 3.01. Calculate the per unit values of 3 sequence reactances. (RGPV Nov 2022)
UNIT-II Relays
Q.1 What are the key considerations when designing fault-sensing relays? (RGPV Dec 2024)
Q.2 How are directional and distance relays represented on an R-X diagram? (RGPV Dec 2024)
Q.3 An Alternator stator winding protected by a differential relay. have a 15% slope of characteristics a fault is occur on winding and the current is 400A through CT1 and 320A through CT2, assuming that the CT ratio of 500/5A, will the relay trip? (RGPV Dec 2024)
Q.4 For what type of protective relay will you recommend ? (RGPV Nov 2023)
i) An induction disc type
ii) Induction cup type construction?
What measures are taken to minimize the overrun of the disc?
Q.5 Determine the time of operation of a 1A. 3s over-current relay having plug setting of 125 per cent and a time multiplier of 0.6. The supplying CT is rated 400:1 A and fault current is 4,000 A. The relay characteristic curve is given below: (RGPV Nov 2023)
|
PSM |
1.3 |
2 |
4 |
8 |
10 |
20 |
|
Time of operations
|
30 |
10 |
5 |
3.3 |
3 |
2.2 |
Q.6 What is advantage of static relay over electromechanical relay? 7(RGPV Nov 2023)
Q.7 Draw the schematic diagram of a numerical relay and briefly describe the functions of its various components. (RGPV Nov 2023)
Q.8 Explain Reverse power relay with neat sketch add all minute constructional detail. (RGPV Nov 2022)
Q.9 Explain in detail the Effect of arc resistance and power swings on performance of distance relay. (RGPV Nov 2022)
Q.10 An IDMT type over current relay is used to protect a feeder through 500/1 Amp CT. the relay has a PS of 125% and TMS 0.3. find the time of operation of the said relay if a fault current of 5000 A flows through the feeder. Make use of following characteristic(RGPV Nov 2022)
|
PSM |
2 |
3 |
5 |
8 |
10 |
15 |
|
Time of Unity
|
10 |
6 |
4.5 |
3.2 |
3 |
2.5 |
(100% current = 1 A).
UNIT-III Protection
Q.1 On what basis, the protection zones in a transmission line are categorized? (RGPV Dec 2024)
Q.2 Explain the role of pilot relaying schemes in transmission line protection. (RGPV Dec 2024)
Q.3 How does the generator-transformer unit protection scheme function? (RGPV Dec 2024)
Q.4 How is power line carrier protection implemented in transmission systems? (RGPV Dec 2024)
Q.5 Explain the term ‘pilot’ with reference to power line protection. What are the different types of pilots which are presently employed? Discuss their fields of application. (RGPV Nov 2023)
Q.6 What is carrier current protection? For what voltage range is it used for the protection of transmission lines? What are its merits and demerits? With neat sketches, discuss the phase comparison scheme of carrier current protection? 7(RGPV Nov 2023)
Q.7 What do you understand by the term ‘PILOT’ in context with power line protection? Explain the concept of power line carrier protection. (RGPV Nov 2022)
Q.8 Explain in detail the transmission line protection in terms of current, time grading and distance. (RGPV Nov 2022)
UNIT-IV Switchgear
Q.1 Compare the characteristics of bulk oil, minimum oil and SF6 circuit breakers. (RGPV Dec 2024)
Q.2 How do HRC fuses function and what are their applications in low-tension switchgear? (RGPV Dec 2024)
Q.3 Explain the criteria for selecting circuit breakers and the importance of testing them. (RGPV Dec 2024)
Q.4 What is the function of an explosion pot in an oil circuit breaker? What are the different types of explosion pot? Describe their construction, working principle and application. (RGPV Nov 2023)
Q.5 What are the different types of air blast circuit breaker? Discuss their operating principle and area of applications. Which type is less affected by current chopping? (RGPV Nov 2023)
Q.6 Discuss the operation principle of SF6, circuit breaker. What are its advantages over other types of circuit breakers? For what voltage range is it recommended? (RGPV Nov 2023)
UNIT-V Modern Trends in Protection
Q.1 Describe the role of microprocessor-based protection schemes. (RGPV Dec 2024)
Q.2 How do logic circuits improve relay functions in protection systems? (RGPV Dec 2024)
Q.3 Discuss about comparators and level detectors in brief. (RGPV Nov 2022)
Extra Questions
Q.1 What is the theory of current interruption and how is energy balance involved? (RGPV Dec 2024)
Q.2 Three Generator are rated as follows: (RGPV Nov 2023)
Generator 1: 100MVA, 33 kV, reactance = 10%
Generator 2: 150MVA, 32 kV, reactance = 8%
Generator 3: 110MVA, 30 kV, reactance = 12%
Choosing 200 MVA and 35 kV as base quantities, compute per unit reactance diagram of the three generates referred to these base quantities. Draw reactance diagram and mark per unit reactances. The three generators are connected to common bus-bars
Q.3 A 3-phase, 66/11 kV star-delta connected transformer is protected by Merz-Price system the CTs on it side have a ratio of 420/5A. Find the ratio of the CT’s on the ht side. (RGPV Nov 2023)
Q.4 Discuss how an amplitude comparator can be converted to a phase comparator and vice versa. (RGPV Nov 2023)
Q.5 Write a short notes on (any two): (RGPV Nov 2023)
i) Line to ground fault
ii) Distance relays on R-X diagram
iii) Bus bar protection
iv) Software development for protection
Q.6 List out followings: (RGPV Nov 2022)
a) Advantages of static relays over electromagnetic relays.
b) Properties of SF6 which makes it suitable for circuit breaker.
— Best of Luck for Exam —
