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ABB
Placement Paper 1 |
TECHNICAL PAPER-40 QUESTION, 45- MINUTES
(1)in a ckt. We r giving voltage of 50 Hz as well as 60.
then what will be
the resultant frequency.
(a)less than 50 (b)more than 60(c)in between 50 & 60
(d)none..........according to our conclusion answer will
be none because if
we apply two frequency component resultatnt frequency we
can not say with
such an ease.U should confirm the answer
2.In a ckt a single resistor is connected across a d.c.
source, what will be
the effect on current in first resistor if we connect
one more resistance in
parallel with earlier one....
Answer.. no change since it is a parallel combination.
3.why we don,t like flashover in transmission line
(t-line)-
(a ) it may create earth fault(b )it reduces the life of
insulator.....
Read something about flashover & puncture.
4.total no of strands in a acsr conductor is 81, then
what is the no. of
conductor in its outer layer....(a)36 (b)18
(c)24.......Also read some more
on acsr.
5.Two questions based on p.u. calculation like , p.u.
calculation is given
with respect to some old base and u have to calculate it
with reference to
new base.
(new resistance/old)=(mva new /mva old)*(old voltage/new
voltage)2.
Other question is based upon transfer of p.u calculation
in
transformer i.e.
how base changes when we we move from primary to
secondary or like wise.read
some more on p.u calculation.
6.which table is referred for sag calculation-
(a)stringing chart......answer
7.in a R-L ckt a ac voltage is applied , such that
instantaneous power is
negative for 2ms, then what will be the
power
factor.
(a) 9 deg, (b) 18 deg, (c) 36 Deg...........(I don't
know the correct ans)
8. In an incandescent lamp
(a) luminous intensity is more than non-luminous
intensity
(b) ,, ,, ,, less ,, ,,
,,
Ans: Since efficiency is less than 100%, hence ans is
(b), u should confirm
it further.
9. In which motor no-load to full-load diff. is lowest
(a) series motor, (b) shunt motor, (c) Compound motor
Ans: (b)
10. In a 60Hz induction motor full load speed is 850 rpm
then what is the
Synchronous speed. (a) 900 rpm, (b) 950 rpm, (c) 1600
rpm....................Ans: (a)
11. A sync. Motor is running at synch. Speed, if al of
sudden D.C.
excitation is removed, then
(a) it will rotate at slip speed, (b) it will stop, (c)
it will continue to
rotate at sync. Speed
Ans: (a), because actually it will acts as Induction
motor.
12. A transmission line is designed for 50Hz, 440KV. If
we want to transfer
power at 60Hz, 440 KV, then the power transfer
capability will
(a) decrease, (b) Increase, (c)None
Ans: (a) ...as P=( |Vt| |Ef| sin (delta) ) / X, where
(delta) is torque
angle.
13. Increased rotor resistance in rotor ckt of induction
motor is related
with
(a) high starting torque, (b) more speed
variation,.....................Ans:
(a)
14. In the formulae E = 4.44 f N Ô, Ô is
(a) Avg value, (b) Rms value, (c) Maximum
value.....................Ans:
(a)...[confirm it]
15. Voltage & current in a ckt is given by V= V1+j V2
and I= I1 +j I2, then
rms power is
.......(refer book by Edministrator on NETWORK ..)
16. Input impedence of MOSFET is
(a) more than BJT........(Ans)
17, 18. Remember truth table of AND, NOR, NAND, OR,
EX-OR ETC...
19. Conversion of Binary number into Equivalent decimal
No.
20. Megger is used for the measurement of (a)
Insulation resistance,
(b)
Conductor resistance.............Ans: (a)
21. Form factor for sinusoidal as well as DC
22. Formulae of Regulation (Vs- Vr)* 100/ Vr, then
transmission line is
(a) short transmission line, (b) long, (c)
medium...................Ans: (a)
23. Improvement in power factor reduces
(a) power consumed by consumer, (b)
power
generation,
(c) both a &
b...........Ans: (c)
[Confirm it]
24. Read about field test of Series Motor...
25. No-load test for Synchronous motor, the graph is
drawn
(a) stator open ckt emf Vs field
current.......................................(Ans: a)
26. An AC voltage of 50Hz is impressed in a resistive
ckt, the oscillating
power has a frequency (a) 50 Hz, (b) 100, (c) no
oscillating power is there
in resistive ckt......Ans: (a)
27. Insulation used in transformer ___________leakage
flux.
(a) increases, (b) decreases............Ans: (b)
28.After rain what happens to Insulator (a) break-down
strength of Insulator
decreases, (b)Arch length reduces, ..........Ans:
(b).....[Confirm it]
29.Diversity factor helps to ............(what ?)
[Read diversity factor, load factor, Reserve capacity
factor in depth, with
calculation]
30. Why capacitance is shown as a Shunt element in
analysis of transmission
line
(a) it is between Conductor & earth, (b) because
Admittance is used for
calculation of capacitive
reactance........................Ans: (a)
31. B-R-Y sequence is followed in three phase system, if
phase voltage in
B-phase is Vm sin 100, then the phase voltage in R-phase
would be (a) Vm
sin (-20)......Ans:(a)
32. In a particular ckt I = Im Sin (wt -270) and V = Vm
Sin wt, then type of
ckt is (a) pure resistive ckt....................[Ans]
33. In a L-R ckt energy lost = 2000 W, energy conserved
= 500W, then what is
the time constant...........Ans: time constant = L/R =
0.5
34. In electro-dynamometer A'meter & wattmeter the type
of scale is
...Ans:Non-uniform
35. For the same current carrying capacity corona loss
of ACSR will be
________than copper conductor. (a) more, (b) less, (c)
equal...Ans:(b)
36. A R-C ckt , supplied with DC, a bulb is connected
across the Capacitor,
then what happens to the illumination, if we change the
capacitance.
Ans: No change at all
37. Read about surge impendence of over-head and
under-ground cable, Surge
impedence formula = sqrt(L/C)
*****[N.B] We are not mentioning the options in
sequence, and do not think
that ans for the most questions is option (a). Read all
options very
carefully as all are very close to each other.
QUANTITATIVE PAPER + PCM paper
45 Questions ---------45 minutes
1. About 10 quanti questions ( based on Mixture, Work
etc. of very easy
type)
2. What is GDP ?
3. Vector algebra, codition for Co-planer vector etc.
4. Gravitation, geo-synchronous satellite( it's hight,
orbit , radius
etc.), escape velocity, how g (gravitational accln)
varies, about
gravitational potential.
5. Basic electricity and Magnetism----Biot-savart law,
current carrying
conductor properties.
6. Nuclear physics, Bohr's constant, and Other theories
related .
7. Problem based on VIBGYOR , how wave length and
frequency is varying.
8. Questions based on Plank's Theory, E =hv
9. V=u + at , V2=u2 + 2as and W = mgh
questions based on above theory
10. Faraday's laws of electrolysis, m = Zit
11. Heat conduction problem.
12. Co lour-coding of resistor (BBROYGBVGW)
13. How velocity of light changes in different medium
while frequency remain
unchanged.
14. statistics , calculation of mode, co-efficient
regression (3-4
Questions)
15. f(x) = Sin x + Cos x, find the maximum value of the
function.......Ans:
sqrt (2)
16. Formulae for parallel plate capacitor and force
between plates.
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