B.Tech-B.Tech Electrical Engineering 6th Sem 6EE3 Protection of Power Systems-6E3111(Rajasthan Technical University-2011)
6E3111
B.Tech. VI Semester (Main/Back) Examination, May/June -2011
Electrical Engineering (Common for EE, EX)
6EE3 Protection of Power Systems
Time: 3 Hours
Maximum Marks: 80
Min. Passing Marks : 24
Unit - I
Q.1. a) Justify qualities and functional characteristics required by a relay with respect to protection. [8]
b) Justify why over-lapping zones of protection are desired for protection purpose. State importance of primary and backup protection. [4+4]
OR
Q.1. a) Differentiate between measurement and protection C.T. State types of current and potential transformers. [6+2]
b) Describe errors in C.T. & P.T. State application of capaCitive voltage transformer. [6+2]
Unit - II
Q.2. a) Describe directional overcurrent relay. Why 30°,60° and 90° connections are required for protection application? [4+4]
b) Why settings of overcurrent relay for Earth Fault relay and phase Fault relay are different? Draw schematic protective schemes for PFR (Phase Fault relay) and EFR(Earth fault relay) [4+4]
OR
Q.2. a) Draw and explain application of overcurrent and directional protective schemes for feeder, ring mains and parallel feeders. [8]
b) The current rating of a relay is 4A, PSM is 1.25, CT ratio is 400/4, fault current is 4000 A. Find the operating time of the relay for a TMS = 0.4. At TMS = 1, the operating time at various PSM are:
Unit - III
Q.3. a) Draw and explain percentage differential protection of a generator. [8]
b) Describe protection of an alternator against unbalanced three phase stator currents. [8]
OR
Q.3. a) Explain protection of an altemator against excitation and prime mover failure. [8]
b) Draw schematic diagram for rotor earih fault protection, for alternator. [8]
Unit - IV
Q.4. a) Draw schematic diagram of percentage differential relay with harmonic restraint and its application. [8]
b) Draw schematic diagram of differential protection of generator - transformer unit. [8]
OR
Q.4. a) Explain and draw schematic diagram of bus bar protection. [8]
b) Explain Buchholz relay in detail and its application for transformer protection. [8]
Unit - V
Q.5. a)Explain 3 stepped distance protection of transmission line and state its advantages. [8]
b) Describe and compare characteristics of impedance, reactance and mho relays with respect to arc resistance and power swings. [8]
OR
Q.5. a) Classify various Faults and abnonnal operating conditions of induction motor. [8]
b) Explain protection ofInduction motor for faults due to source/supply side. [8]
| Earning: ₹ 6.50/- |
