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2013-06-20APTRANSCO 2012 ELECTRICAL Previous PaperAPTRANSCO 2012 KEY ELECTRICAL

1.

1.A voltage waveform v(t)= 12 t2is applied across a 1H inductor for t>=0 withinitial current through it being zero. The current through the inductor fort>=0 is given by-----------(4t3)

2.Two incandescent light bulbs fo 40w and 60w ratingare connected in series across the mains. Then--------(the 40 bulb glows brighter)

3.Given two coupled inductors L1 and L2, their mutualinductances M satisfies-----(M

4.Consider the star network. The resistance betweenterminals A and B with C open 6ohms, between terminals B and C with A open is11ohms, and between terminals C and A with B open is 9ohms. Then------------(Ra=2, Rb=4, Rc=7)

5.In a series RLC circuit at resonance, the magnitudeof the voltage developed across the capacitor------( can be greater than theinput voltage, however, it is 900out of phase with the input voltage)

6.A two port device is defined by the following pairof quations:

i1=2v1+v2 and i2=v1+v2 its impedance parameters(z11, z12, z21, z22) are-----(1,-1,-1,2)

7.The impulse response of an initially relaxed linearsystem is e-2tu(t).to produce a response of

te-2tu(t), the input must be equalto--------(e-2tu(t))

8.The no of roots on the equation 2s4+s3+3s2+5s+7=0that lie in the right half of s plane is-------(2)

9.For a feedback control system of type 2, the steadystate error for a ramp input is-------(zero)

10.The output of a linear time invariant controlsystem is c(t) for a certain input r(t). if r(t) is modified by passing itthrough a block whose transfer function is e-s and then applied to the system,the modified output of the system would be-----------(c(t-1)u(t-1)

11.The phase lead compensation used to-----(decreasesboth rise time and overshoot)

12.Consider two buses connected by an impedance of(0+j5)ohm. The bus 1 voltage is 100/300v, and bus 2 voltage is 100/00v. the real and reactive power supplied by bus 1,resp are.(1000w, 268 VAr)

13.For a fixed value of complex power flow in atransmission line having a sending end voltage V, the real power loss will beproportional to-----------(1/V2).

14.During a disturbance on a synchronous machine, therotor swings from A to B before finally settling down to a steady state atpoint C on the power angle curve. The speed of the machine during oscillationis synchronous at point(s)--------------------(A and B)

15.A 100 MVA, 11kv, 3 phase 50hz, 8 pole synchronousgenerator has an inertia constant H equal to 4 MJ/MVA. The stored energy in therotor of the generator at synchronous speed will be---(400MJ).

16.In a biased differential relay the bias is definedas a ratio of----------(operating coil current and restraining coil current))

17.Resistance switching is normally employedin------(ABCB)

18.The use of high speed circuit breakers----(improvessystem stability)

19.Keeping in view the cost and overall effectiveness,the following circuit breaker is best suited for capacitor bankswitching---(vacuum)

20.If the reference bus is changed in two load flowruns with the same system data and power obtained for reference bus taken asspecified P and Q in the latter run----------( the system losses will beunchanged but complex bus voltages will change.)

21.The gauss seidel load flow method has followingdisadvantages. Tick the incorrect statement------( unreliable convergence)

22.The torque speed characteristics of a repulsionmotor resembles which of the following dc motorcharacteristic------------(series)

23.Which type of motor is most suitable for computerprinter drive-----(stepper motor)

24.A 4 pole lap wound DC generator has a developedpower of P watts and voltage of E volts. Two adjacent brushes of the machineare removed as they are worn out. If the machine operates with the remainingbrushes, the developed voltage and power that can be obtained from the machineare----(E,P/4)

25.A 4 point starter is used to start and control thespeed of a -----------( dc shunt motor with field weakening control)

26.The function of oil in a transformer is-----( toprovide insulation and cooling)

27.The core flux of a practical transformer with aresistive load------------( is strictly constant with load changes)

28.In a transformer zero voltage regulation at fullload is----(possible at leading pf load)

29.A single phase transformer has a turns ratio of1:2, and is connected to a purely resistive load. The magnetizing current drawnis 1 A, and the secondary current is 1A. if core losses and leakage reactanceare neglected, the primary current is-(2.24A)

30.The low voltage winding of a 400/230V, single phase50hz transformer is to be connected to a 25hz, the supply voltage shouldbe-------(115V)

31.A 400/100V, 10 KVA two winding transformer isreconnected as an auto transformer is reconnected as an auto transformer acrossa suitable voltage source. The maximum rating of such an arrangement couldbe-----(50KVA)

32.When the supply voltage to an induction motor isreduced by 10%, the maximum torque will decrease by approximately-------(20%)

33.In case of a split phase motor, the phase shiftbetween currents in the two windings is around------(300)

34.Starting torque can be obtained in the case of asingle phase induction motor with identical main and auxiliary windings byconnecting-----( a capacitor in series with the auxiliary winding)

35.For a single phase capacitor start induction motorwhich of the following statements is valid---( the direction of rotation can bechanged by reversing the main winding terminals)

36.An induction motor having full load torque of 60zNmwhen delta connected develops a starting torque of 120Nm. For the same supplyvoltage, if the motor is changed to star-connection, the starting torquedeveloped will be-------(40NM)

37.During hunting of synchronous motor (damper bardevelops torque)

38.The phase sequence of a three phase alternator willreverse if -------(the field current remains the same but the direction ofrotation is reversed)

39.The effect of stray magnetic fields on theactuating torque of a portable instrument is max when the operating filed ofthe instrument and the stray fields are-(parallel)

40.A current of -8+6

(sinwt+300)A is passed through threemeters. They are a center zero PMMC meter, true rms meter and MI instrument.The respective reading( in A) will be----(-8,10,10)

41.R1 and R2 are the opposite arms of a wheatstonebridge as are R3 and R, the source voltage is applied across R1 and R3 underbalanced conditions which one of the following is true---(R1=R2R3/R4)

42.A dc potentiometer is designed to measure up toabout 2v with a slide wire of 800mm. a standard cell of emf 1.18v obtainsbalance at 6010mm. a test cell is seen to obtain balance at 680mm. the emf ofthe test cell is-(1.34v)

43.The minimum number of wattmeters required tomeasure3 phase 3 wire or unbalanced power is(2)

44.A reading of 120 is obtained when a standardinductor was connected in the circuit of a Q meter and the variable capacitoris adjusted to a value of 300pF. A lossless capacitor of unknown value C, isthen connected and the same reading was obtained when the variable capacitor isreadjusted to a value of 200pF. The value of Cx in pF is(100)

45.The two inputs of a CRO are fed with the twostationary periodic signals. In the X Y mode, the screen shows a figure whichchanges from ellipse to circle and back to ellipse with its major axis changingorientation slowly and repeatedly. The following inference can be made fromthis----------(there is a constant but small phase difference between thesignals)

46.SCR can be turned off( anode current should beless than holding current)

47.The no. of pn junctions in SCR-----(3)

48.TRIAC is a(antiparallel thyristors combination)

49.GTO can be turned off-(by using a negative currentpulse)

50.Which type of control is used for controlling theac drive by using thyristors--------(integral cycle)

51.In DC choppers the output voltage can be controlledby using FM technique varying--------( T , Toff constant)

52.In phase control rectifiers the output voltageripple can be controlled by(load inductance)

53.Which is not a current controlleddevice-----(MOSFET)

54.Inverter function---------(DC to AC with variablefrequency)

55.In phase controlled rectifires free wheeling diodemakes-(load current continuation)

56.Dielectric heating application----(wood)

57.In induction heating the following is abnormallyhigh--------(frequency)

58.Tractive effect w.r.t driving wheelaxis--------(tangential*)

59.welding transformer sets have-------------(highcurrent, low voltage)

60.Simplifyxyz+xyz+xyz+xyz+xyz=-------(yz+yz+xz)

61. Find out y=-----------------(P+Q+R+S)

OTHER PAPERS

AP TRANSCOELECTRICAL - TECHNICAL PAPER

SUB-ENGINEERSTECHNICAL PAPER 2012

ENGINEERSTECHNICAL PAPER 2012

ELECTRICALPAPER -SOME IMPORTANT QUESTIONS

AP GENCO -TECHNICAL PAPER

TECHNICALPAPER 2012

TECHNICALPAPER 2011

AP CPDCLELECTRICAL - TECHNICAL PAPER

TECHNICALPAPER 2010

BHEL ELECTRICAL- - TECHNICAL PAPER

TEHNICALPAPER 2010

TEHNICALPAPER 2009

2013-06-20APTRANSCO 2012 ELECTRICAL Previous PaperAPTRANSCO 2012 KEY ELECTRICAL

1.

1.A voltage waveform v(t)= 12 t2is applied across a 1H inductor for t>=0 withinitial current through it being zero. The current through the inductor fort>=0 is given by-----------(4t3)

2.Two incandescent light bulbs fo 40w and 60w ratingare connected in series across the mains. Then--------(the 40 bulb glows brighter)

3.Given two coupled inductors L1 and L2, their mutualinductances M satisfies-----(M

4.Consider the star network. The resistance betweenterminals A and B with C open 6ohms, between terminals B and C with A open is11ohms, and between terminals C and A with B open is 9ohms. Then------------(Ra=2, Rb=4, Rc=7)

5.In a series RLC circuit at resonance, the magnitudeof the voltage developed across the capacitor------( can be greater than theinput voltage, however, it is 900out of phase with the input voltage)

6.A two port device is defined by the following pairof quations:

i1=2v1+v2 and i2=v1+v2 its impedance parameters(z11, z12, z21, z22) are-----(1,-1,-1,2)

7.The impulse response of an initially relaxed linearsystem is e-2tu(t).to produce a response of

te-2tu(t), the input must be equalto--------(e-2tu(t))

8.The no of roots on the equation 2s4+s3+3s2+5s+7=0that lie in the right half of s plane is-------(2)

9.For a feedback control system of type 2, the steadystate error for a ramp input is-------(zero)

10.The output of a linear time invariant controlsystem is c(t) for a certain input r(t). if r(t) is modified by passing itthrough a block whose transfer function is e-s and then applied to the system,the modified output of the system would be-----------(c(t-1)u(t-1)

11.The phase lead compensation used to-----(decreasesboth rise time and overshoot)

12.Consider two buses connected by an impedance of(0+j5)ohm. The bus 1 voltage is 100/300v, and bus 2 voltage is 100/00v. the real and reactive power supplied by bus 1,resp are.(1000w, 268 VAr)

13.For a fixed value of complex power flow in atransmission line having a sending end voltage V, the real power loss will beproportional to-----------(1/V2).

14.During a disturbance on a synchronous machine, therotor swings from A to B before finally settling down to a steady state atpoint C on the power angle curve. The speed of the machine during oscillationis synchronous at point(s)--------------------(A and B)

15.A 100 MVA, 11kv, 3 phase 50hz, 8 pole synchronousgenerator has an inertia constant H equal to 4 MJ/MVA. The stored energy in therotor of the generator at synchronous speed will be---(400MJ).

16.In a biased differential relay the bias is definedas a ratio of----------(operating coil current and restraining coil current))

17.Resistance switching is normally employedin------(ABCB)

18.The use of high speed circuit breakers----(improvessystem stability)

19.Keeping in view the cost and overall effectiveness,the following circuit breaker is best suited for capacitor bankswitching---(vacuum)

20.If the reference bus is changed in two load flowruns with the same system data and power obtained for reference bus taken asspecified P and Q in the latter run----------( the system losses will beunchanged but complex bus voltages will change.)

21.The gauss seidel load flow method has followingdisadvantages. Tick the incorrect statement------( unreliable convergence)

22.The torque speed characteristics of a repulsionmotor resembles which of the following dc motorcharacteristic------------(series)

23.Which type of motor is most suitable for computerprinter drive-----(stepper motor)

24.A 4 pole lap wound DC generator has a developedpower of P watts and voltage of E volts. Two adjacent brushes of the machineare removed as they are worn out. If the machine operates with the remainingbrushes, the developed voltage and power that can be obtained from the machineare----(E,P/4)

25.A 4 point starter is used to start and control thespeed of a -----------( dc shunt motor with field weakening control)

26.The function of oil in a transformer is-----( toprovide insulation and cooling)

27.The core flux of a practical transformer with aresistive load------------( is strictly constant with load changes)

28.In a transformer zero voltage regulation at fullload is----(possible at leading pf load)

29.A single phase transformer has a turns ratio of1:2, and is connected to a purely resistive load. The magnetizing current drawnis 1 A, and the secondary current is 1A. if core losses and leakage reactanceare neglected, the primary current is-(2.24A)

30.The low voltage winding of a 400/230V, single phase50hz transformer is to be connected to a 25hz, the supply voltage shouldbe-------(115V)

31.A 400/100V, 10 KVA two winding transformer isreconnected as an auto transformer is reconnected as an auto transformer acrossa suitable voltage source. The maximum rating of such an arrangement couldbe-----(50KVA)

32.When the supply voltage to an induction motor isreduced by 10%, the maximum torque will decrease by approximately-------(20%)

33.In case of a split phase motor, the phase shiftbetween currents in the two windings is around------(300)

34.Starting torque can be obtained in the case of asingle phase induction motor with identical main and auxiliary windings byconnecting-----( a capacitor in series with the auxiliary winding)

35.For a single phase capacitor start induction motorwhich of the following statements is valid---( the direction of rotation can bechanged by reversing the main winding terminals)

36.An induction motor having full load torque of 60zNmwhen delta connected develops a starting torque of 120Nm. For the same supplyvoltage, if the motor is changed to star-connection, the starting torquedeveloped will be-------(40NM)

37.During hunting of synchronous motor (damper bardevelops torque)

38.The phase sequence of a three phase alternator willreverse if -------(the field current remains the same but the direction ofrotation is reversed)

39.The effect of stray magnetic fields on theactuating torque of a portable instrument is max when the operating filed ofthe instrument and the stray fields are-(parallel)

40.A current of -8+6

(sinwt+300)A is passed through threemeters. They are a center zero PMMC meter, true rms meter and MI instrument.The respective reading( in A) will be----(-8,10,10)

41.R1 and R2 are the opposite arms of a wheatstonebridge as are R3 and R, the source voltage is applied across R1 and R3 underbalanced conditions which one of the following is true---(R1=R2R3/R4)

42.A dc potentiometer is designed to measure up toabout 2v with a slide wire of 800mm. a standard cell of emf 1.18v obtainsbalance at 6010mm. a test cell is seen to obtain balance at 680mm. the emf ofthe test cell is-(1.34v)

43.The minimum number of wattmeters required tomeasure3 phase 3 wire or unbalanced power is(2)

44.A reading of 120 is obtained when a standardinductor was connected in the circuit of a Q meter and the variable capacitoris adjusted to a value of 300pF. A lossless capacitor of unknown value C, isthen connected and the same reading was obtained when the variable capacitor isreadjusted to a value of 200pF. The value of Cx in pF is(100)

45.The two inputs of a CRO are fed with the twostationary periodic signals. In the X Y mode, the screen shows a figure whichchanges from ellipse to circle and back to ellipse with its major axis changingorientation slowly and repeatedly. The following inference can be made fromthis----------(there is a constant but small phase difference between thesignals)

46.SCR can be turned off( anode current should beless than holding current)

47.The no. of pn junctions in SCR-----(3)

48.TRIAC is a(antiparallel thyristors combination)

49.GTO can be turned off-(by using a negative currentpulse)

50.Which type of control is used for controlling theac drive by using thyristors--------(integral cycle)

51.In DC choppers the output voltage can be controlledby using FM technique varying--------( T , Toff constant)

52.In phase control rectifiers the output voltageripple can be controlled by(load inductance)

53.Which is not a current controlleddevice-----(MOSFET)

54.Inverter function---------(DC to AC with variablefrequency)

55.In phase controlled rectifires free wheeling diodemakes-(load current continuation)

56.Dielectric heating application----(wood)

57.In induction heating the following is abnormallyhigh--------(frequency)

58.Tractive effect w.r.t driving wheelaxis--------(tangential*)

59.welding transformer sets have-------------(highcurrent, low voltage)

60.Simplifyxyz+xyz+xyz+xyz+xyz=-------(yz+yz+xz)

61. Find out y=-----------------(P+Q+R+S)

OTHER PAPERS

AP TRANSCOELECTRICAL - TECHNICAL PAPER

SUB-ENGINEERSTECHNICAL PAPER 2012

ENGINEERSTECHNICAL PAPER 2012

ELECTRICALPAPER -SOME IMPORTANT QUESTIONS

AP GENCO -TECHNICAL PAPER

TECHNICALPAPER 2012

TECHNICALPAPER 2011

AP CPDCLELECTRICAL - TECHNICAL PAPER

TECHNICALPAPER 2010

BHEL ELECTRICAL- - TECHNICAL PAPER

TEHNICALPAPER 2010

TEHNICALPAPER 2009

1. In a dc shunt motor the terminal voltage is halved while the torque is kept constant. The resulting approximate variation in speed and armature current Ia will be(A) Both and Iaare doubled.(B) is constant and Iais doubled(C) w is doubled while Iais halved(D) w is constant but Iais halvedAns: B

2.The current from the stator of an alternator is taken out to the external load circuit through(A) slip rings.(B) commutator segments.(C) solid connections.(D) carbon brushes.Ans: C3.A motor which can conveniently be operated at lagging as well as leading power factors is the(A) squirrel cage induction motor.(B) wound rotor induction motor.(C) synchronous motor.(D) DC shunt motor.Ans: C4 The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about(A) 50 Hz.(B) 20 Hz.(C) 2 Hz.(D) Zero.Ans: C5.The size of a conductor used in power cables depends on the(A) operating voltage. (B) power factor.(C) current to be carried. (D) type of insulation used.Ans: C6. The most suitable servomotor for low power applications is(A) a dc series motor.(B) a dc shunt motor.(C) an ac two-phase induction motor.(D) an ac series motor.Ans: B7.A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be(A) 4.5%. (B) less than 4.5%. (C) more than 4.5%. (D) 4.5% or more than 4.5%.Ans: C8 When a synchronous motor is running at synchronous speed, the damper winding produces(A) damping torque.(B) eddy current torque.(C) torque aiding the developed torque.(D) no torque.Ans: D9 If a transformer primary is energised from a square wave voltage source, its output voltage will be(A) A square wave.(B) A sine wave.(C) A triangular wave.(D) A pulse wave.Ans: A10 In ad.c.series motor the electromagnetic torque developed is proportional to(A) Ia(B) (Ia)2(C) 1/Ia(D) 1/(Ia)2Ans: B11.The two windings of a transformer is(A) conductively linked.(B) inductively linked.(C) not linked at all.(D) electrically linked.Ans : B12.In a 3 phase induction motor running at slip s the mechanical power developed in terms of air gap power(A) (s-1)Pg( B) Pg/(1-s)(C) (1-s)Pg(D) s.PgAns: C13. In a 3 phase induction motor the maximum torque(A) is proportional to rotor resistance r2(B) does not depend on r2(C) is proportional to sqrt(r2)(D) is proportional to (r2)2Ans: B13 In ad.c.machine, the armature mmf is(A) stationary w.r.t. armature.(B) rotating w.r.t. field.(C) stationary w.r.t. field.(D) rotating w.r.t. brushes.Ans: C14 In a transformer the voltage regulation will be zero when it operates at(A) unity p.f.(B) leading p.f.(C) lagging p.f.(D) zero p.f. leading.Ans: B15. A salient pole synchronous motor is running at no load. Its field current is switched off. The motor will(A) come to stop.(B) continue to run at synchronous speed.(C) continue to run at a speed slightly more than the synchronous speed.(D) continue to run at a speed slightly less than the synchronous speed.Ans: B16.The maximum power in cylindrical and salient pole machines is obtained respectively at load angles of(A) 900,900(B) 900(D) 900,