Save as PDF
Opens your browser print dialog — select "Save as PDF" to download.
Total No. of Questions : 8]
[Total No. of Printed Pages : 2
Roll No.......................
MEHP/MEPS/MTPS-103
M.E./M.Tech. I Semester
Examination, December 2024
Advance Power System Protection Relays
Time : Three Hours
Maximum Marks : 70
Note: i) Attempt any five questions.
ii) All questions carry equal marks.
1.
a) Explain the basic principles of protective relays. Discuss their importance in power system protection.
7
b) Define a differential relay and describe its working principle. How does it compare to other protective relays in fault detection?
7
2.
a) Explain the working principle of over-current relays with a diagram and list their types.
7
b) What are distance relays? Explain their principles and types for transmission line protection.
7
3.
a) Define static relays and compare their advantages and disadvantages with electromechanical relays.
7
b) What is a smoothing circuit in static relays, and how does it enhance performance?
7
4.
a) Explain how mixing transformers in comparators enhance phase and amplitude comparison accuracy in relay circuits.
7
b) Derive the general equation of a phase and amplitude comparator. Discuss how this equation is applied in protective relaying.
7
5.
a) Describe the protection of the stator windings of 3-phase alternator against turn-to-turn faults.
7
b) A 6.6 kV, 4000 kVA star-connected alternator has a transient reactance of 2 Ω per phase and negligible resistance. It is protected by a circulating current protective system, with the alternator neutral earthed through a 7.5 Ω resistor. The relays are set to operate when there is an imbalance of 1 A in the secondary windings of the 500/5 current transformers. What percentage of each phase winding is protected against an earth fault?
7
6.
a) Explain the principle of percentage differential relay protection. Why is it particularly useful for protecting generators and transformers?
7
b) Explain the working principles of directional wave detection relays and their application in transmission line protection.
7
7.
a) Discuss types of digital relays in power system protection and their advantages over traditional systems.
7
b) Explain the working principle of microprocessor-based relays and their applications in power systems.
7
8.
a) Discuss the causes of ratio and phase angle errors in CTs. How can these errors be minimized?
7
b) Discuss phase compensation carrier protection and its role in long-distance transmission lines.
7