ABB Placement Paper -2 MAY 2007,VADODRA

**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 resultant 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 arcs 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 Ф, Ф 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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