Bangalore University 2003-2nd Sem B.E First/ester , y/ust - Question Paper
Page No... ELE15/25
I NEW SCHEME I
A.l.T. UORARY
USN
First/Second Semester B.E. Degree Examination, July/August 2003
Common to all branches (New Scheme)
. i .
Time: 3 hrs.] [Max.Marks : 100
Note: Answer any FIVE full questions.
(k) State and explain Faraday's laws of electro magnetic Induction, Lenz's Law. Fleming's right hand rule and Flemings left hand rule. (io Marks)
(b) A coll of300 turns wound on a core of non magnetic material, has an Inductance of lOmH. Calculate 1) the flux produced by a current of 5A U) the average value of the emf induced when a current of 5Amps Is reversed in 8 milli seconds.
(K Marks)
(cj With .a,neat sketch briefly explain how an alternating voltage is produced when a coil is rotated in a magnetic field. (5 Marks)
2v{afDeiive expressions for average value and RMS value of a sinusoidally varying
AC VOltage. (6 Marks)
. .. ,-f i .
(b) A circuit haying a resistance of 12fi, an Inductance of 0.151T and a capacitance
jf 100nf ln series is connected across a 100V, 50Hz supply. Calculate the impedance., current, the phase difference between the current and supply VOltage. , (6 Marks)
(c) Two circuits with impedances of Z-t = 10+_7l5il and Zz = 6 - j 8fl are connected kiparaiiel. If the supply current is 20A, what is the power dissipated in each branch? (8Mub)
.) What are the advantages of a three phase system over a single phase system?
(4 Marks)
(b) With a neat clrcuit diagram and a vector diagram prove that two,wattmeters are sufficient to measure total power ln a 3 phase system. (s Marks)
(c) A balanced star connccted load of (8 + jf)Q ls connected to a 3 phase, 230V supply. Find the line current, power factor, power, reactive voltamperes and total voltamperes. (s Marks)
(a) With a neat sketch explain the construction and working of a single phase induction type energymeter. (8 Marks)
(b),-Wlth a neat circuit diagram and a switching table, explain the two point control of a lamp. (6 Marks)
(c) With a neat sketch explain the pipe earthing method. (6 Marks)
page No.,-'. 2 of a d c machtnc and the function of
s ,a| Draw the cross sectional view ,
each part. torcwe lu ft dc motor and dhow that the
(b) Derive an exPreJ the product of flux and armature current. to Hubs
torque is propo poles and a wave connected winding wtth 432
(c) A 500V shunt motor has 0 05 wb. The l\iU load ciuvent la 20 Amps-, conductors. The fliix perPfield resistances air 0.U1 and 2MU1 renpecttvciy. The armature and sh" developed torque.
Calculate the speed and tn
, . ,h ronstructional details ot ecur type and siw*l
6. la) With neat sketches plain the
Tleequauonofauansionner. d Derive th iqoo/415V 50Hz slngie phase tnmafonucr Uas 80 turns on the
secondary. Calculat sccondary currents
n the rated primary and secon ar>
m ' the number of primary turns
!llt) the xnaximum value of flux - . . .
ivi voltage induced per turn.
' , the working of a 3 point tarter fbr n DC motor
7 (a) With a ne*'- sketch exp , P
(7Mufcc
. I
(7 Ma&fcafe
, . rortruct'.onal detail o( *n *Hemator. Wtth eat sketches explatn the con. . ,T**
1 tor has a star connected winding with 144 slots and
(cl A 3phase, V6 pole altemai 0.03 Wb and the peed Is STS
io conductors per slot.
RPM. f and line emi, Assume yktteh factor Kp \
Find the frequent, the ,5
and distribution factor Kj
le of operation of a 3 phase Induction motwr. is itubi 8. (a) Explain the principle o g poies and ran at 900 RTM on Ml load.
(b) A 3 phase "nator having 4 pole# and runnhvfc 1 1300 Km.
It is suppU1 from and the frequency of the rotor current of tiw
Calculate the full 08 (T uubi
inducUon motor fof an induction motor? \VUh ft neat oltvuH dunur.
(cl Why are startersnecr a 3 phase induction motor. 1 w
. explain ft star delta star-.
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| Earning: Approval pending. |
