Placement Papers: ABB Vadodra Paper 2 May 2004

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

    1. less than 50

    2. 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-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.

    1. 9 deg

    2. 18 deg

    3. 36 Deg____ (I don't know the correct ans)

  8. In an incandescent lamp

    1. luminous intensity is more than non-luminous intensity

    2. , 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

    1. series motor

    2. shunt motor

    3. 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

    1. it will rotate at slip speed

    2. it will stop

    3. 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

    1. decrease

    2. Increase

    3. None

    Ans: (a) … As P = (| Vt | Ef | sin (delta) )/X, where (delta) is torque


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

    1. high starting torque

    2. more speed variation

  14. In the formulae E = 4.44 f N, is

    1. Avg value

    2. Rms value

    3. Maximum value____

  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 more than BJT____ (Ans) 17, 18. Remember truth table of AND, NOR, NAND, OR, EX-OR ETC…

  17. Conversion of Binary number into Equivalent decimal No.

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

  19. Form factor for sinusoidal as well as DC

  20. Formulae of Regulation (Vs-Vr) * 100/Vr, then transmission line is

    1. short transmission line

    2. long

    3. medium____Ans: (a)

  21. Improvement in power factor reduces

    1. power consumed by consumer

    2. power generation

    3. both a & b

  22. Read about field test of Series Motor…

  23. No-load test for Synchronous motor, the graph is drawn stator open ckt emf Vs field current (Ans: a)

  24. 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)

  25. Insulation used in transformer ___________leakage flux.

    1. increases

    2. decreases____Ans: (b)

  26. After rain what happens to Insulator (a) break-down strength of Insulator decreases (b), Arch length reduces, ____Ans: (b) Not Known[Confirm it]

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

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

    1. it is between Conductor & earth

    2. because Admittance is used for calculation of capacitive reactance____Ans: (a)

  29. 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)

  30. In a particular ckt I = Im Sin (wt-270) and V = Vm Sin wt, then type of ckt is (a) pure resistive ckt [Ans]

  31. 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

  32. In electro-dynamometer A'meter & wattmeter the type of scale is Ans: Non-uniform

  33. For the same current carrying capacity corona loss of ACSR will be ________than copper conductor.

    1. more

    2. less

    3. equal.

    Ans: (b)

  34. 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

  35. Read about surge impendence of over-head and under-ground cable, Surge impedence formula = sqrt (L/C)

Quantitative Papers

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.