RTU 2016 Question Paper Semester VIII Electrical and Electronics Engineering Protection of Power System

o3los | **r6

ca
v B.Tech. VIII Semester (Main) Examination, April 2016
€
-
Electrical and Electronics Engineering
FnI
€ 8EX3A Protection of Power System
Common with 8EE3A

Time:3 Hours Maximum Marks : 80
Min. Passing Marks : 24
Instructions to Candidates:
Attempt anyfive questions, selecting one questionfrom each unit. All questions
carry equol marlcs. (Schematic diagrams must be shown wherever necessory.
Any data you feel missing suitably be assumed and stated clearly.)
lJnits of quantities used/calculated must be stared clearly

Unit _ I
1. a) What are the different tvngs of faults? Which type of fault is most dangerous.
.And gxplain essential qualities of a protective relay. And also opfui" il-r Uurit
operation oftrip circuit with suitable circuitdiagram (10)
b) Explain what you understand by primary and back-up prbtection. what are
the va.ous methods of providing back-up protection - ^ (6),

OR
1. a) ?tuy the magnetizationcharacteristics of protective and measurement CTs.
And give the comparison betw"., *eur*ing crs and protective crs. (s)
b) Derive phase angle and ratio error for pT? (g)
Unit - II
2' a) Classifu and explain different types of over current relays. And also draw
rvercurrenr relays
characteristics of various ore.cu.rent relays (g)
b) The current {a!rc of an over current relay is 5,4,. The relay has a plug-setting
of l5A% and Time Multiplier
-time Setting(Ti\4S) of o.+. nre'Ci ratio is 400/5.
Determine the operating of the"relay for u fault current of 60004. At
. TMs-l operating time at various psM are given in the table-I

8ftfi#43 h,o,u (1) ICont...

v

Table-I

PSM 2 10 20
Operatingtime \
in seconds 10 2.8 2.4 (8)
OR
) a) Discuss the protective scheme for a feeders (S)
b) Describe the construgliol principle of operation of a directional overcurrent
::lrl;*l1how
the 00, 00, 90 0 i omecti ons
3 6 air..ti"rrf ;;;;;;.nt relay
are oDtatned "f (8)
, flnit - ilI
3. a) Describe the c-onskuction and operating principle of the percentage differential
'r9layr How the percentage didr."tiuirltuy
simpledifferentialrelay - ---
-J o',ro"orn"s the drawbacks of the
(10)
b) Explain different upes of faurts occur in generator (6)
OR
3. a) Describe the negative sequence protection schemes
for generator (8)
b)
lxplain stator inter-turn fault protection for multi turn generator with suitable
circuit diagram (g)
Unit _ IV
4. Mlt is magnetizinginrush cturent? What measures are taken to distinzuish between
the fautt current and magn etizing ir*;h ;;;;r?
r;i#r;;ir;;;",f;iu..r"h.*"
which protects the traniformer'agai;;t i;;ld'b.rl aoe.rr"i
magnetizing inrush current
Jp..;; in case of
(16)
OR
4. a) Explain the construction and working of Buchholz
*-^*^'relay.J Against
faults Buchholz relay gives the proteJtion- e- -'--'
which
(g)
b) What is frame leakage protection of busbar? Discuss its principle and field
of application.
(g)
Unit _ V
5. What is universal Torque equation? Using this
equation derive and draw following
characteristics

, Impedancerelay

: rl I
888043 (2\

ii) Reactance relay 1

iii) Mtro relay
/
/ And also discuss the application ofthe im@ance relay, reactance relay and
Mho relay. (16)

OR
5. a) Explain the three stepped distance protection of transmission line (S)
' b) Describe the protection provided to Induction motors for earth faults (8)

8EE043 (3)