Placement Papers: ABB Placement Paper 2 May 2007 Vadodra
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TECHNICAL PAPER40 QUESTION, 45MINUTES

In a ckt, We r giving voltage of 50 Hz as well as 60. Then what will be the resultant frequency.

less than 50

more than 60

in between 50 & 60

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


In a ckt a single resistor is connected across a dc 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.

why we don't like flashover in transmission line (tline) 

it may create earth fault

it reduces the life of insulator.
Read something about flashover & puncture.


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.

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.

which table is referred for sag calculationstringing chart answer

in a RL ckt a ac voltage is applied, such that instantaneous power is negative for 2ms, then what will be the power factor.

9 deg

18 deg

36 Deg. (I don't know the correct ans).


In an incandescent lamp

luminous intensity is more than nonluminous intensity

, less,
Ans: Since efficiency is less than 100%, hence ans is (b), u should confirm it further.


In which motor noload to fullload diff. Is lowest

series motor

shunt motor

Compound motor
Ans: (b)


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)

A sync. Motor is running at synch. Speed, if al of sudden D. C. Excitation is removed, then

it will rotate at slip speed

it will stop

it will continue to rotate at sync. Speed
Ans: (a)


A transmission line is designed for 50Hz, 440KV. If we want to transfer power at 60Hz, 440 KV, then the power transfer capability will

decrease

Increase

None
Ans: Decrease as P = ( Vt  Ef  sin (delta) )/X, where (delta) is torque angle.


Increased rotor resistance in rotor ckt of induction motor is related with

high starting torque

more speed variation, Ans: (a)


In the formulae E = 4.44 f N? is

Avg value

Rms value

Maximum value


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. ).

Input impedence of MOSFET is more than BJT. (Ans).

Remember truth table of AND, NOR, NAND, OR, EXOR ETC

Conversion of Binary number into Equivalent decimal No.

Megger is used for the measurement of (a) Insulation resistance (b), Conductor resistance. Ans: (a)

Form factor for sinusoidal as well as DC

Formulae of Regulation (VsVr) * 100/Vr, then transmission line is

short transmission line

long

medium. Ans: (a)


Improvement in power factor reduces

power consumed by consumer

power generation

both a & b


Read about field test of Series Motor

Noload test for Synchronous motor, the graph is drawnstator open ckt emf Vs field current (Ans: a)

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)

Insulation used in transformer ___________leakage flux.

increases

decreases Ans: (b)


After rain what happens to Insulator (a) breakdown strength of Insulator decreases (b), Arch length reduces, Ans: (b)? [Confirm it]

Diversity factor helps to (what?) [Read diversity factor, load factor, Reserve capacity factor in depth, with calculation]

Why capacitance is shown as a Shunt element in analysis of transmission line

it is between Conductor & earth

because Admittance is used for calculation of capacitive reactance
Ans: (a)


BRY sequence is followed in three phase system, if phase voltage in Bphase is Vm sin 100, then the phase voltage in Rphase would be (a) Vm sin (20) Ans: (a)

In a particular ckt I = Im Sin (wt270) and V = Vm Sin wt, then type of ckt is (a) pure resistive ckt. [Ans]

In a LR ckt energy lost = 2000 W, energy conserved = 500W, then what is the time constant. Ans: Time constant = L/R = 0.5

In electrodynamometer A'meter & wattmeter the type of scale is Ans: Nonuniform

For the same current carrying capacity corona loss of ACSR will be ________than copper conductor (a). more (b), less (c), equal Ans: (b)

A RC 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

Read about surge impendence of overhead and underground cable, Surge impedence formula = sqrt (L/C)
Quantitative Paper
45 Questions____45 minutes

About 10 quanti questions (based on Mixture, Work etc. Of very easy type)

What is GDP?

Vector algebra, codition for Coplaner vector etc.

Gravitation, geosynchronous satellite (it's hight, orbit, radius etc.), escape velocity, how g (gravitational accln) varies, about gravitational potential.

Basic electricity and Magnetism____Biotsavart law, current carrying conductor properties.

Nuclear physics, Bohr's constant, and Other theories related.

Problem based on VIBGYOR, how wave length and frequency is varying.

Questions based on Plank's Theory, E = hv

V = u + at, V2 = u2 + 2as and W = mgh questions based on above theory

Faraday's laws of electrolysis, m = Zit

Heat conduction problem.

Co lourcoding of resistor (BBROYGBVGW)

How velocity of light changes in different medium while frequency remain unchanged.

statistics, calculation of mode, coefficient regression (3 − 4 Questions)

f (x) = Sin x + Cos x, find the maximum value of the function. Ans: Sqrt (2)

Formulae for parallel plate capacitor and force between plates.