University of Pune 2010-1st Sem B.Tech - ester-Basic electrical engineering - Question Paper
Total No. of Questions : 12] [Total No. of Printed Pages : 4
F. E. (Semester - I) Examination - 2010 BASIC ELECTRICAL ENGINEERING (2008 Pattern)
Time : 3 Hours] [Max>Vlarks : 100
Instructions :
(1) Answers to the two sections should ejwritten in separate answer-books.
(2) Answer Q. No. 1 or Q. No. NO. 3 or Q. No. 4, Q. No. 5 or Q. No. 6, Q. No\Y or Q. No. 8, Q. No. 9 or Q. No. 10 and Q. or Q. No. 12.
(3) Figures to the right ind(cpje full marks.
(4) Neat diagrams mustftg drawn wherever necessary.
(5) Use of non-progfpmmaole pocket size scientific calculator is permitted. SsJ
(6) Assume suitam&idditional data, if necessary.
What is Iifsdation Resistance ? State its unit and obtain an
Q.l) (A)
(B)
expression for Insulation Resistance of the Cable. [08]
Withu3at sketch explain Construction and Working of Lead AcTtNCell. [08]
OR
(Al A resistance element having cross-sectional area of 10 mm2 "A and length of 10 meter takes a current of 4 Amp from 200V supply at temperature of 25C. Find (i) resistivity of the material and (ii) current it will take when temperature rises to
Q.2)
75C. Assume a
,0003/C.
[06]
Explain what do you mean by Statically Induced emf and Dynamically Induced emf ? [06]
A steel ring of 25 cm mean diameter and of circular crosssection 3 cm diameter has an air gap of 1.5 mm length. It is wound uniformly with 700 turns of wire carrying va current of 2 Amp. Calculate :
Q.6) (A)
(B)
mg aci
(a) MMF
(b) Flux Density
(c) Reluctance and
(d) Relative Permeability of Steel Ring
Define w.r.t. alternating quantities\j
Q.7) (A)
(a) Instantenous Value
(b) Waveform \
(c) Cycle
\
(d) Amplitude \j
(e) Periodic Time
(f) Frequency
Sketch Waveforrtof Currents and find its rms value and average valuator the equation : [08]
(a) ij
(b) i,
h
(B)
5 sin (314.159 t) and 10 sin (314.159 t - n/2)
OR
A
Q.8) (A) Proekhat rms value of the sinusoidal alternating current is 0.707
tinjes its maximum value. [06]
(B)_ ETerive expression for energy stored in a capacitor.
[06]
Two capacitors of 50jlF each are connected in parallel with each other and this combination is connected in series with two capacitors of 80|LiF of 40|HF each. Calculate equivalent capacitance of the circuit. [05]
P.T.O.
Define and explain following terms :
(a) Active Power
Q.9) (A)
[08]
(b) Reactive Power
(c) Impedance
(d) Admittance
A C ircuit consisting of Resistance of 20"2 and IndtttJKinCe of
(B)
0.1 Henry is connected in series across single phe 200V, 50 Hz supply. Calculate :
(a) Current Drawn
(b) Power Consumed
(c) Draw relevant Phasor Diagram
[09]
A Coil of Resistance 50Q and Inductanaof 0.1 H is connected in parallel with a branch which Consists of resistance of 45Q in series with a capacitor of 100 ptf across a single phase 230V, 50Hz supply. Calculate (&j*ent, Power and p.f. of the Circuit. X.
Q.10) (A)
[09]
If a sinusoidal voltage of yV Vm sinwt is applied across R-C series circuit, derive expression for current drawn and power consumed. Draw 'heir waveforms also.
(B)
[08]
[08]
Write short notes : /O)
Q.ll) (A)
(a) Losses takingvplaceNn Transformer
(b) An AutotranMSarmer
Draw a compflgjfejrfiasor diagram for a 3 phase delta connected inductive balanced load supplied for 3-phase symmetrical A.C. supply. Staiequation for Active Power and Reactive Power consumed by Load.
(B)
[08]
hftFrrced Star Connected Load is supplied by 3-phase, 415V,
Q.12) (A) A
supply. C urrent in phase is 2 0 Amp and iags 30c behind
rteJphase voltage. Find : va) Power Consumed by Load y\(b) Circuit Parameters, and
(c) Load p.f.
[08]
(B) Explain working principle of transformer and derive expression for emf induced in its winding.
[08]
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