TRB Poly Technic Lecturer Previous Year Question Ee
TRB Poly Technic Lecturer Previous Year Question Ee
TRB Poly Technic Lecturer Previous Year Question Ee
INSTRUCTIONS
1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION, YOU SHOULD CHECK
THAT THIS TEST BOOKLET DOES NOT HAVE ANY UNPRINTED OR TORN OR MISSING PAGES
OR ITEMS, ETC. IF SO, GET IT REPLACED BY A COMPLETE TEST BOOKLET.
2. ENCODE CLEARLY THE TEST BOOKLET SERIES A, B, C OR D AS THE CASE MAY BE IN THE
APPROPRIATE PLACE IN THE RESPONSE SHEET.
Your Roll No.
3. You have to enter your Roll Number on this
Test Booklet in the Box provided alongside.
DO NOT write anything else on the Test Booklet.
4. This Booklet contains 120 items (questions). Each item comprises four responses (answers). You will select
one response which you want to mark on the Response Sheet. In case you feel that there is more than one
correct response, mark the response which you consider the best. In any case, choose ONLY ONE response
for each item.
5. In case you find any discrepancy in this test booklet in any question(s) or the Responses, a written
representation explaining the details of such alleged discrepancy, be submitted within three days, indicating
the Question No(s) and the Test Booklet Series, in which the discrepancy is alleged. Representation not
received within time shall not be entertained at all.
6. You have to mark all your responses ONLY on the separate Response Sheet provided. See directions in the
Response Sheet.
7. All items carry equal marks. Attempt ALL items. Your total marks will depend only on the number of
correct responses marked by you in the Response Sheet.
8. Before you proceed to mark in the Response Sheet the response to various items in the Test Booklet, you
have to fill in some particulars in the Response Sheet as per instructions sent to you with your Admit Card
and Instructions.
9. While writing Centre, Subject and Roll No. on the top of the Response Sheet in appropriate boxes use
ONLY BALL POINT PEN.
10. After you have completed filling in all your responses on the Response Sheet and the examination has
concluded, you should hand over to the Invigilator only the Response Sheet. You are permitted to take away
with you the Test Booklet.
2. The resistance between the opposite faces of 1m. cube is found to be 1!". If its length is increased
to 2 m, with its volume remaining the same, then its resistance between the opposite faces along its
length is :
(A) 2 ! (B) 4 !
(C) 1 ! (D) 8 !
3. Three resistances of 3 !"each are connected in delta. The value of the resistances in the
equivalent star is :
(A) 27 (B) 9
(C) 1.5 (D) 1 !
11. A high pass filter has a resistance R = 2 k!$"The lowest input frequency to be passed is 7.5 KHz.
The value of suitable coupling capacitor must be :
(A) 0.1 pF (B) 1 pF
(C) 0.1 %"F (D) 1 %"F
12. In the network shown the value of the current supplied by the battery will be :
13. In a Circuit, a resistance R, a pure inductance L, and a Capacitance C are connected in parallel
across a sinusoidal voltage source of V volt. The circuit current will lead the applied voltage if :
(A) Ic < IL (B) Ic = IL
(C) Ic > IL (D) None of these
s&2
14. For V ( s ) ' , the initial and final values of V(t) will be respectively :
s ( s & 1)
(A) 1 and 1 (B) 2 and 2
(C) 2 and 1 (D) 1 and 2
10
15. Inverse Laplace transform of is :
s ( s & 1)
(A) 10 [1 + e-t] (B) 10 [ 1 + et]
(C) 10 [ 1 e-t] (D) 10 [ 1 et]
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16. Impulse response of an RL circuit is a :
(A) Rising exponential function (B) Decaying exponential function
(C) Step function (D) Parabolic function
18. In a network containing resistances and reactances the roots of the characteristic equation give
for the circuit :
(A) The forced response (B) The total response
(C) The natural response (D) The damped response
20. The transfer function of a first order control system is of the type :
1 1
(A) Ts 2 & 1 (B) Ts &1
1
(C) Ts (D) Ts
21. The response c(t) of a system to an input r(t) is given by the following differential equation
d 2c (t) dc ( t )
&3 & 5c ( t ) ' 5r ( t )
dt 2 dt
The transfer function of the system is given by :
5 1
(A) G (s) ' 2 (B) G (s) ' 2
s & 3s & 5 s & 3s & 5
3s s&3
(C) G (s) ' 2 (D) G (s) ' 2
s & 3s & 5 s & 3s & 5
26. The number of roots in the right half of s-plane for the equation s3 4s2 + s + 6 = 0 would be :
(A) 1 (B) 2
(C) 3 (D) 4
27. If the Nyquist plot cuts the negative real axis at a distance of 0.4, then the gain margin of the
system is :
(A) 0.4 (B) -0.4
(C) 4% (D) 2.5
30. If the system specifications are given in time domain, best approach for designing is :
(A) Nyquist Plot (B) Bodes Plot
(C) Root Locus (D) None of these
1 1
(C) % 0 (0 (D) % (
0 0
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32. Maxwells divergence equation for the magnetic field is given by :
(A) (B)
(C) (D) ) B ' *
35. The value of d l along a circle of radius 2 units is :
(A) Zero (B) 2 +
(C) 4 + (D) 8 +
)#-
#B %''/'037.
*0 Which one of the statements does not pertain to the equation ) B ' 0 :
BB ,
(A) There are no sinks and sources for magnetic fields
(B) Magnetic field is perpendicular to the electric field
(C) Single magnetic pole cannot exist
(D) B is solenoidal
38. An air filled rectangular waveguide has dimensions 6 cm, 4 cm. The cut off frequency for TE10 is :
(A) 2.5 GHz (B) 25 GHz
(C) 25 MHz (D) 5 GHz
(A) (B) - . / %
42. If V, w, q stand for voltage, energy and charge then V can be expressed as :
dw
(A) (B) V ' dq
dw dq
(C) dV ' dq (D) dV '
dw
43. A null type of instrument as compared to a deflection type instrument has :
(A) a higher accuracy (B) a lower sensitivity
(C) a faster response (D) all of the above
44. The usage of electronic instruments is becoming more extensive because they have :
(A) a high sensitivity and reliability
(B) a fast response and compatibility with digital computers
(C) the capability to respond to signals from remote places
(D) all of the above
46. An 0-10 A ammeter has a guaranteed accuracy of 1% of full scale deflection. The limiting error
while reading 2.5 A is :
(A) 1% (B) 2%
(C) 4% (D) None of the above
48. The voltage of a circuit is measured by a voltmeter having an input impedance comparable with
the output impedance of the circuit thereby causing error in voltage measurement. This error may
be called :
(A) Gross error (B) Random error
(C) Error caused by misuse of instrument (D) Error caused by loading effect
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49. The most stable primary atomic standard for frequency is :
(A) Caesium beam standard (B) Hydrogen maser standard
(C) Quartz standard (D) Rubidium vapour standard
50. The material of wires used for making resistance standards is usually :
(A) Manganin (B) Nichrome
(C) Copper (D) Phosphor Bronze
52. The relative damping in a galvanometer is 0.8. Its logarithmic decrement is approximately :
(A) 0.48 (B) 1.25
(C) 4.19 (D) 4.19
56. Electronic Voltmeters which use rectifiers employ negative feedback, this is done :
(A) to increase the overall gain (B) to improve stability
(C) to overcome non-linearity of diodes (D) none of the above
64. A carrier is simultaneously modulated by two sine waves with modulation indices of 0.3 and 0.4;
the total modulation index :
(A) is 1
(B) cannot be calculated unless the phase relations are known
(C) is 0.5
(D) is 0.7
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65. To provide two or more voice circuits with the same carrier, it is necessary to use :
(A) ISB (B) Carrier reinsertion
(C) SSB with pilot carrier (D) Lincompex
66. One of the following cannot be used to remove the unwanted sideband in SSB, this is the :
(A) Filter system (B) Phase-shift method
(C) Third method (D) Balanced modulator
68. To prevent overloading of the last IF amplifier in a receiver, one should use :
(A) Squelch (B) Variable sensitivity
(C) Variable selectivity (D) Double Conversion
71. After a target has been acquired, the best scanning system for tracking is :
(A) Nodding (B) Spiral
(C) Conical (D) Helical
78. A 400/200 V transformer has a pu impedance of 0.05. The HV side voltage required to circulate
full load current during short circuit test is :
(A) 40 V (B) 20 V
(C) 10 V (D) 5 V
79. Phase relationship between mmf phasor and emf phasor in a synchronous machine is :
(A) leads by 90
(B) lags by 90
(C) and are in phase
(D) This angle depends upon the pf of the load
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82. Which of the following statements is correct ?
(A) Xd and Xq are different in a round rotor machine at lagging pf only
(B) Xd and Xq are different in a round rotor machine at any pf
(C) Xd and Xq are different in a salient pole machine at lagging pf only
(D) Xd and Xq are different in a salient pole machine at any pf
83. If stator impedance is neglected, the maximum torque in an induction motor occurs at a rotor
resistance of :
(A) (1 + s) x2 (B) (1 s) x2
(C) sx2 (D) x2
(C) T 0 1 s (D) T 0 s
87. In a 25-KVA 3300/230 V, single phase transformer the iron and full load copper losses are
350 W and 400 W respectively. The load at which the efficiency will be maximum is :
(A) 25 KW (B) 21.875 KW
(C) 25 KVA (D) 21.875 KVA
88. A 3-12 6 pole induction motor operates on 440 V, 50Cls supply. If the actual speed of the motor
is 960 rpm, the slip will be :
(A) 6% (B) 5%
(C) 4% (D) 0.4%
89. When an induction motor runs at rated load and speed, the iron losses are :
(A) negligible (B) very heavy
(C) independent of supply frequency (D) independent of supply voltage
91. Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. The
highest speed of the alternator is :
(A) 3600 rpm (B) 3000 rpm
(C) 600 rpm (D) 500 rpm
96. For a load flow solution the quantities normally specified at a voltage controlled bus are :
(A) P and Q (B) P and |V|
(C) Q and |V| (D) P and 3
98. The voltages at the two ends of a line are 132 KV and its reactance is 40 ohms. The capacity of
the line is :
(A) 435.6 MW (B) 217.5 MW
(C) 251.5 MW (D) 500 MW
99. For stability and economic reasons we operate the transmission line with power angle in the range :
(A) 10 to 25 (B) 30 to 45
(C) 60 to 75 (D) 65 to 80
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100. Ferranti effect on long overhead lines is experienced when it is :
(A) On full load at unity pf (B) Lightly loaded
(C) On full load at 0.8 pf lag (D) In all these cases
102. A transformer rated for 500 KVA, 11 KV/0.4 KV has an impedance of 10% and is connected
to an infinite bus. The fault level of the transformer is :
(A) 500 KVA (B) 5000 KVA
(C) (D) None of these
103. In a pure LC parallel circuit under resonance condition, current drawn from the supply mains is :
(A) Very large (B) V LC
(C) V / LC (D) Zero
105. Severe over-voltages are produced during arcing faults in a power system with the neutral :
(A) isolated (B) solidly earthed
500 3 KVA
(C) earthed through a low resistance (D) none of these
106. The zero sequence impedance of different elements of power system is generally :
(A) equal (B) zero
(C) different (D) none of these
114. A converter which can operate in both 3-pulse and 6-pulse modes is a :
(A) 1-1 full converter (B) 3-1"half wave convertor
(C) 3-1 semi converter (D) 3-1"full converter
115. A 1-1"full bridge inverter can operate in load-commutation mode in case load consists of :
(A) RLC overdamped (B) RLC underdamped
(C) RLC critically damped (D) None of these
116. In circulating-current type of dual converter, the nature of voltage across reactor is :
(A) alternating (B) pulsating
(C) direct (D) triangular
118. In a single pulse modulation of PWM inverters, the pulse width is 120. For an input voltage of
220V dc, the rms value of output voltage is :
(A) 179.63 V (B) 254.04 V
(C) 127.02 V (D) None of these
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119. In a dual converter, converters 1 and 2 work as under :
(A) 1 as rectifier, 2 as inverter (B) both as rectifiers
(C) both as inverter (D) none of these
120. In a constant source inverter, if frequency of output voltage is f Hz. Then frequency of voltage
input to constant source inverter is :
(A) f (B) 2f
(C) 3f (D) 4f
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