MCC - TRB - Eee - 2021 - Answer Key
MCC - TRB - Eee - 2021 - Answer Key
MCC - TRB - Eee - 2021 - Answer Key
ELECTRICAL
1. The phase lag-lead network shifts the phase of control signal in order
that output phase :
A) lags at low frequencies and leads at high frequencies
B) leads at all frequencies
C) leads at low frequencies and lags at high frequencies
D) becomes independent of frequencies
Solution:
Lag-lead compensator is a type of electrical equipment that generates lag
as well as phase lead in the output signal at different frequencies when
steady state sinusoidal output is provided to it.
𝑧
2. The time shifting property of z-transform is written as if x(n) x(z), then
𝑧 𝒛
A) x(n-k) zk+1 x(z) B) x(n-k) z-k x(z)
𝑧 𝑧
C) x(n-k) zk x(z) D) x(n-k) z-k+1 x(z)
Solution :
By time shifting property
𝑍
𝑥 𝑛−𝑘 𝑍 −𝑘 𝑋(𝑍)
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
3. The final stage of a multistage amplifier uses __________.
A) Transformer coupling
B) RC coupling
C) Impedance coupling
D) Direct coupling
Solution :
Final stage of multistage Amplitier uses Transformer coupling for
Impedance matching in Transistor amplifier
4. Pulse position Modulator electronic circuit operates on __________ mode.
A) Astable B) Monostable
C) Bistable D) Both Monostable and Bistable
Solution:
PPM is nothing but PWMT monostablemultivibrator. It we fed PWMo/p
the trigger i/p of IC555 in monostable mode then the output of
monostable will be Pulse position modulated wave
5. In an R-L-C series transient circuit, the output current wave yields a
critical damped case when :
𝑅 1 𝑅 2 1 2 𝑅 1 𝑹 𝟐 𝟏
A) = B) = C) = D) =
2𝐿 𝐿𝐶 2𝐿 𝐿𝐶 2𝐿 𝐿𝐶 𝟐𝑳 𝑳𝑪
Solution :
For Series RLC circuit
2
1 𝑅
𝜉= −
𝐿𝐶 2𝐿
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Solution :
𝑆𝑢𝑚 𝑜𝑓 𝐼𝑛𝑑𝑖𝑣 𝑖𝑑𝑢𝑎𝑙 max 𝐷𝑒𝑚𝑎𝑛𝑑𝑠
Diversity factor =
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝑜𝑛 𝑝𝑜𝑤𝑒𝑟 𝑠𝑡𝑎𝑡𝑖𝑜𝑛
Maximum Demand of Power Station is always less than the sum of
individual maximum Demand of Consumer
Hence Diversity factor is always greater than unity.
7. Corner frequencies of bode plot of lead compensator are ω1 and ω2. The
maximum phase lead angle given
1
A) 𝝎𝟏× 𝝎𝟐 B) 𝜔1+𝜔2 C) D) 𝜔1 × 𝜔2
𝜔 1× 𝜔 2
Solution :
The 𝜔m for lead compensator is given by
𝜔𝑚 = 𝜔1 ∗ 𝜔2
A) 0 B) 2 C) 4 D)1/4
Solution :
1 1
lim𝑠→0 𝑠. 𝑆(𝑆+2)2 = 4
Solution :
Shunts are made of manganin as they have low value of temperature
co-efficient
11. A sinusoidal flux 0.02 Wb (maximum) links with 55 turns of transformer
secondary. Calculate the RMS value of the induced emf in secondary.
The supply frequency is 50 Hz.
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Solution :
m= 0.02wb
N= 55
F= 50 Hz
E2 = 4.44 fmN
= 4.44x50x0.02x55.
= 244.2v
A) 0.5 to 0.65
B) 0.45 to 0.6
C) 0.4 to 0.55
D) 0.5 to 0.6
Solution :
E = 90 to 120V
Vin = 200V
Vo = E+IR
When E= 90 When E=120
Vo = 90+10 Vo=120+10
Vo = 100 Vo=130
𝑉𝑜 100 130
𝐷 = 𝑉𝑠 𝐷 = 200 D= 200
D= 0.5 D=0.65
D= 0.5 to 0.65
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
15. If peak overshoot of system is 100% then damping ratio is :
A) 1
B) Infinity
C) 0.5
D) 0
Solution :
for % Mp = 100%
−𝜋𝜉
16. 'Mango showers' rainfall are common in South India during the month of
A) August and September
B) December and January
C) April and May
D) February and March
Solution :
* The signal (xh) is said to be causal if x(n)=0 for n< 0.
* x(n) = an u(n) Is causal signal
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
𝐺𝑀𝐷
L=0.2 ln 𝑆𝑒𝑙𝑓 𝐺𝑀𝐷
Self GMD = 0.7788 r
0 −3
20. If −3
𝑔 𝑡 = 2 then 0
𝑔 𝑥 𝑑𝑥 is :
1 −1
A) B) C) − 2 D) 2
2 2
Solution :
0
−3
𝑔(𝑡) = 2
−3
0
𝑔 𝑡 𝑑𝑡 = − 2
𝑏 𝑎
This given by 𝑎
𝑡 𝑛 𝑑𝑥 = − 𝑏
𝑓 𝑛 𝑑𝑥
21. The power input to a 3 phase induction motor is 60 kW. The total stator
loss is 1 kW. Find the mechanical power developed, if the motor is
running with a slip of 3%.
A) Pm=30 kW
B) Pm=44 kW
C) Pm=50.77 kW
D) Pm=57.23 Kw
Solution :
Pin = 60 kw
Stator loss = 1 kw
Pag = 60-1 =59 kw
Pm = (1-5) pag = (1- 0.03)x 59
Pm = 57.23.kw
22. The value of the preset current above which the relay operates is known
as :
23. Who was the Revenue Minister during Rajaji's first Regime ?
A) K. Kamaraj
B) O.P. Ramaswami Reddiar
C) R. Shunmugham Chetty
D) T. Prakasam
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
24. Which one of the following is correct answer with respect to Region of
Convergence (ROC) ?
𝑆+4.41
25. If lead compensator for a system is given by; Gc(s) = Kc × 𝑆+18.4. Then the
new gain cross over frequency of compensated system is given by:
26. Find the current and the voltage drop across the 5Ω resistor for the
circuit shown :
A) 2 A, 5 V B) 2 A, -10 V C) -2 A, 5 V D) 2 A, 10 V
Solution :
By KCl
10+I = 5+7
I = 12-10 = 2A
V= 2×5=10V
27. If the breaker reclose after some time corresponding to clearing angle δc
when the fault vanished, the output will be more than the input and
hence the rotor :
A) Decelerates
B) Stand still
C) No change
D) Accelerates
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
28. Which Inscription mentions Pandyan Nedunjeliyan ?
A) Mangulam Inscriptions
B) Alagar Malai Inscriptions
C) Pugalur Inscriptions
D) Tiruparankundram Inscriptions
Solution :
For an ammeter meter, Voltage drop should be low. To maintain
low values of voltage Drop , the ammeters are made of 10 𝜔 values
of resistances
* For a Voltmeter. Current drawn should be low. Therefore
voltmeters are made of high values of resistances.
Solution :
Resolution is smallest change in input signal which can be detected by
the instrument
31. Two alloys contain Silver and Copper in the ratio of 3 : 1 and 5 : 3. In
what ratio the two alloys should be added together to get a new alloy if
Silver and Copper in the ratio 2 : 1 ?
A) 3 : 6 or 1 : 2
B) 3 : 2 or 1 : 3
C) 6 : 3 or 1 : 2
D) 1 : 2 or 3 : 6
Solution :
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
3 5
Alloy 1 silver= Alloy2 silver=
4 8
1 3
𝑐𝑢 = 𝑐𝑢 =
4 8
Let Ration be x: 1
2 5
𝑆𝑖𝑙𝑣𝑒𝑟 𝑥+ 2
4 8
= 1 3 =1
𝑐𝑢 𝑥+
4 8
6𝑥+5 2
=1
2𝑥+3
6x+5= 4x+6
2
2x=1 x= 1
1
Ratio: x:1→ 2 1 → 1: 2 𝑜𝑟 3: 6
32. When a L-L fault occurs, the zero sequence current is j 3.553 p.u. The
fault current in this case will be :
A) 3 * j 3.553 p.u.
B) 2 x j 3.553 p.u.
C) 2 × j 3.553 p.u.
D) 𝟑 × j 3.553 p.u.
A) 16Ω B) 32Ω C) 8Ω D) 4Ω
Solution :
Rth = 8||8 = 4
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
35. A resistance is classified as low resistance if its resistance value is :
A) Above 10 Ohms
B) More than one but below 5 Ohms
C) Below 10 Ohms
D) Below one Ohm
Solution :
10𝜔Resistance → R≤ 1
Medium Resistance →1< 𝑅 < 100𝑘
High Resistance → R> 100𝑘
36. A discrete time system is called as static if its output at any instant 'n'
depends on the input sample at the :
A) same and past time
B) same and future time
C) same time only
D) future time only
Solution :
* The system is said to static system if at any instant ‘n’
depands on the input sample at the same time only
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
39. In an R-L-C series circuit connected to an alternating current source, at
resonance, the voltage magnification occurs across :
A) capacitor
B) resistor, inductor and capacitor combination
C) resistor
D) resistor and inductor combination
Solution :
1) The magnitude of voltage across the inductor of capacitor is Q
times the input minusoidal Voltage
2) Voltage magnification occurs at L&C
𝒅𝟐 𝒚 𝟑
A) -3y = (𝒆𝒛 -3)
𝒅𝒁𝟐 𝟒
𝑑2 𝑦 𝑑𝑦
B) -2 + 12y = 3(𝑒 𝑧 -3)
𝑑𝑍 2 𝑑𝑍
𝑑2 𝑦 3
C) +3y = (𝑒 𝑧 +3)
𝑑𝑍 2 4
𝑑2 𝑦 𝑑𝑦
D) -2 + 12y = 3(𝑒 𝑧 +3)
𝑑𝑍 2 𝑑𝑍
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
A) 8 B) 𝟒 C) 2 D) 6
46. A cascade forward path compensator designed for a system has transfer
𝑆+0.05
function given by Gc(s) = 𝑆+0.005
This compensator will improve the following :
A) Peak overshoot of the system
B) Damping factor of the system
C) Steady state error of the system
D) None of the options
Solution :
1
𝑠+
Gc(s) = 𝑇
1
𝑠+
𝐵𝑇
Given compensator is lag compensator hence it reduces steady
state error
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
47. The order of differential equation governing a system having its polar plot
as shown in below :
A) 3 B) 2 C) 0 D)1
Solution :
1
The Transfer function of given poles plot is G(s)H(s) =
1+𝑆𝑇1 1+𝑆𝑇2 1+𝑆𝑇3
49. Find the value of the load resistance (RL) for the given circuit under the
condition of maximum power transfer :
A) 25Ω B) 3Ω C) 4Ω D) 2Ω
Solution :
[[(2||2)+4]||5]||2.5]+1.75 = Rth
Rth = 1.25+1.75 = 3
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Solution :
Eph = 4.44 KpKdpN f ф𝑚 T
Kp< l for short pitch coil.
Eph is reduced
52. The voltage across R and L in a series R-L circuit are found to be 40 V
and 30 V respectively. The r.m.s. value of the voltage across the series
combination is :
A) 80 V
B) 25 V
C) 45 V
D) 50 V
Solution :
V= 402 + 302
V=50V
Solution :
𝜔𝑛2 = 25
𝜔𝑛 = 5
2ξ𝜔𝑛 = 5 2
2ξx5=5 2
1
ξ = 2
𝑀𝑟 = 1
54. A 250 V, 4 pole wave wound dc series motor has 782 conductors on its
armature. Ithas armature and series field resistance of 0.75Ω. The
motor takes a current of 40 A. Estimate its gross torque developed if it
has a flux per pole of 25 mWb.
A) 300 N-m
B) 400.7 N-m
C) 347.5 N-m
D) 249 N-m
Solution :
𝑍𝑁𝑃
Eb= 𝐴
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Eb= V- IaRa
= 250- 40x0.75
Eb = 220V
𝑃
Ta= 0.159xZIa 𝐴
0.159𝑥25𝑥10 −3 𝑥782𝑥40𝑥4
Ta= 2
Ta= 249Nm
Solution :
The relay detects abnormal condition of Sends trip signal to circuit
Breaker
Solution :
Definite lime O.C relay the Operating time is constant and Independent
of pick value
57. The stator loss of a 3 phase induction motor is 2 kW. When the power
input is 90 kW. What will be the rotor copper loss and mechanical
power developed if the motor is running at a 4% slip ?
A) 3.52 kW and 84.48 kW
B) 9.8 kW and 65.32 kW
C) 4.63 kW and 80 kW
D) 6.32 kW and 78.32 Kw
Solution :
Pin=90 kW
Pststor =2k𝜔
Pag = 88k𝜔
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Protorcu = Pag × S
= 88 × 0.04
= 3.52k𝜔
Pm = Pag × (1-s)
= 88 × 0.96
= 84.48k𝜔
Solution :
Solution :
62. The widespread fire in the forest of Indonesia in 1997-98 was related to
drought resulting from :
A) El Nino event
B) 'Slash and burn' agriculture
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
C) La Nino event
D) Faulty water resource management
63. The value to which the power factor should be improved so as to have
maximum net annual saving is known as the :
A) Unity power factor
B) Best power factor
C) Most economical power factor
D) Maximum power factor
Solution :
If the consumer improver pf, then KVA demand will reduce
whild will lead to annual saving over the maximum demand changes. But
the consumer has to bean annual expenditure for the pf Correction
equipment Hence, the most economical Pf is defined as the value of
which PF should be Improved so as to have maximum net annual saving.
64. The average current rating of a semiconductor diode will be maximum for
A) pure ac
B) half wave rectified ac
C) full wave rectified ac
D) pure dc
Solution :
𝑉𝑚
Average Current of Pure ac=
2
𝑉𝑚
Full Wave rectified = 2
𝑉𝑚
Half Wave rectified = 2
Pure Dc = Vm
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
66. In a two-quadrant dc-dc chopper, the load voltage is varied from positive
maximum to negative maximum by varying the time-ratio of the chopper
from :
A) zero to 0.5
B) unity to zero
C) 0.5 to zero
D) zero to unity
Solution :
A) Low inductance
B) High resistance
C) Low resistance
D) High inductance
Solution :
Measurement of resistance:
Low R: Kelvin double bridge, potentio meter
Medium R: Wheatstone, Substitution Method
High R: Loss of change, Megger
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Solution :
For 4 Pole D 50 Hz IM,
120×50
𝑁𝑠 = 4 = 3000rpm
Rated Speed = 2850
3000 −2850
rated slip = 3000 = 0.05
Now Motor is run with half slip at 40 Hz,
0.05
S= 2 = 0.025 Nr = (1-s) Ns
Nr = 2925 rpm
N∝f
for 50 HZ, 2925rpm
for 40 HZ = 2925x40 50
= 2340 rpm
71. The roll-off rate of an active filter __________ with the order of the filter.
A) No Change
B) Increases
C) Both Decreases and Increases
D) Decreases
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Solution :
Total roll- off = ∆𝐿𝑇 = n∆𝐿
Order increases , roll –off increases
A) Vcc consideration
B) Rc consideration
C) R1 and R2
D) RE consideration
Ans(*)
75. The capacitance of the diode will __________ exponentially with increase
in the forward bias voltage.
A) Increase
B) Decrease
C) Reduce by half
D) No change
Solution :
∈𝐴
C= 𝑑
Forward bias increases, the depletion region width ‘d’ reduces, C increases,
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
76. The stator of 3 phase induction motor has 3 slots per pole per phase. If
supply frequency is 50 Hz, the speed of the rotating stator flux is
__________.
A) 1250 rpm B) 1500 rpm C) 1000 rpm
D) 750 rpm
77. Which of the following vector diagram is Correct for the circuit shown ?
A)
B)
C)
D)
Solution:
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Given circuit has pure capacitance as load. Hence current leade Voltage
by 900 option D alone satiffies.
𝑑𝑊
78. If W=U (X,Y) + Iv (X,Y) is an analytic function of z, then is :
𝑑𝑍
𝝏𝑾 𝜕𝑊 𝜕𝑊 𝜕𝑊
A) –i B) i C) –i D) –i
𝝏𝒀 𝜕𝑌 𝜕𝑋 𝜕𝑋
Solution :
80. If L[f(t)] = ф(s) then the relation between the Laplace transform of f(t) and
f(at) is :
Solution :
81. For the power semiconductor devices IGBT, MOSFET, diode and
transistor, which one of the following statements is TRUE ?
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
B) MOSFET is majority carrier device, whereas IGBT, diode and
thyristor are minority carrier devices
C) All the four are majority carrier devices
D) IGBT and MOSFET are majority carrier devices, whereas diode and
thyristor are minority carrier devices
Solution :
82. If the reactive power generation violates, the voltage controlled bus is
made to act as a:
A) Generator bus
B) Load bus
C) Slack bus
D) Reference bus
Solution :
Solution :
𝐸𝑉
P= sin𝛿
𝑋
𝐸𝑉
𝑃𝑚𝑎𝑥 = 𝑋 sin90𝑜
𝛿 = 90𝑜 → P = 𝑃𝑚𝑎𝑥
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
84. A half controlled single-phase bridge rectifier is supplying an R-L load. It
is operated at a firing angle α and the load current is continuous. The
fraction of cycle that the freewheeling diode conduct is :
∝ ∝ ∝
A) ½ B) C) 1 − 𝜋 D)
𝝅 2𝜋
Solution :
88. If the Fourier Transform of f(x) is F(s) then the Fourier transform of
f(x)cos ax is :
𝟏
A) [F(s+a) + F(s – a)] B) F(s+a)-F(s-a)
𝟐
1
C) [F(s+a) - F(s – a)] D) F(s+a)+F(s-a)
2
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
89. In a digital protection scheme, the component necessary to make the
signals from the transducer compatible with the analog interface is :
A) Filters
B) Current transformer
C) Signal conditioner
D) Analog multiplexer
Ans(*)
A) Generators
B) Transformers
C) Bus bars
D) HV and EHV transmission lines
Solution :
𝑤1 = 3𝑉𝐿 𝐼𝐿 cos(30 + ∅)
𝑤2 = 3𝑉𝐿 𝐼𝐿 cos(30 − ∅)
𝑤1 = 𝑤2 two watt meter need equally only when power factor angle is 0𝑜
93. The phase difference between the input signal and output signal voltage
of a transistor connected in common-Emitter configuration is
__________.
A) 1800
B) 00
C) 900
D) 2700
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
94. For the circuit shown, the time varying current is given by :
96. The power delivered to a star connected load of R Ω per phase, from a 3-
phase bridge inverter fed from fixed dc source is 10 kWfor 180o
mode. For 120 mode, the power delivered to load would be :
o
A) 7.5 kW B) 6.667 kW C) 5 kW D) 10 Kw
97. If the sum of three Eigen values and trace of 3 x 3 matrix A are equal,
then the value of determinant of A is :
A) 0 B) 1 C) 3 D) 2
Ans(mark to all)
𝑗𝜔𝑇
98. The polar plot of G(j𝜔) = for 0≤ 𝜔 ≥ ∞ is :
1+𝑗𝜔𝑇
A) Hyperbolic
B) Circular
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
C) Parabolic
D) Elliptical
99. A signal x(n) is periodic with period N(N > 0) if and only if :
Solution :
𝜕2𝑍
100. The solution of = sinxy is :
𝜕𝑌 2
𝟏
A) Z = - sin (xy) + yф(x) + g(x)
𝑿𝟐
1
B) Z = sin (xy) + xf(y) + g(y)
𝑋2
1
C) Z = sin (xy) + yф(x) + g(x)
𝑌2
1
D) Z = - sin (xy) + xf(y) + g(y)
𝑌2
Solution :
𝜕2𝑧
= sin 𝑥𝑦
𝜕𝑦 2
Integrate on both side
𝜕2𝑧
= sin 𝑥𝑦
𝜕𝑦 2
𝜕𝑧 sin 𝑥𝑦
=- +∅
𝜕𝑦 𝑥
sin 𝑥𝑦
Z=- + y∅(x)+g(x)
𝑥2
A) continuous , 2π
B) discontinuous, 2π
C) discontinuous, 𝜋/2
D) continuous, 𝜋/2
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
102. The knowledge of __________ is quite helpful in high voltage
measurements.
A) RMS value
B) Form factor
C) Peak value
D) Crest factor
103. A 746 kW, 3 phase, 50 Hz, 16 pole induction motor has rotor impedance
of (0.02+j0.15) Ω at standstill. Full load torque is obtained at 360 rpm.
Determine the speed at which maximum torque will occur __________.
A) 400 rpm
B) 350 rpm
C) 430 rpm
D) 325 rpm
Solution :
104. The radio interference due to corona is of importance for line above
__________kV.
A) 200
B) 500
C) 100
D) 600
105. MOSFETs are preferred for high frequency applications. The reason that
can be attributed to this property is :
A) positive temperature co-efficient of the MOSFETs
B) smaller leakage current of MOSFETs
C) high input impedance of the MOSFETs
D) the absence of minority storage charge in the MOSFETs
Solution :
When compare to BJT, MOSFET is more suitable for high frequency (as
turn off timing decreases frequency increases) and this is due to small
turn-off time due to absence of minority carrier storage time.
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
106. The transmission line loading condition, in which the VARs absorbed are
equal to the VARs generated is called :
A) Natural impedance
B) Capacitive reactance
C) Inductive reactance
D) Surge impedance
Solution :
Solution :
109. The higher rate of oscillation in a discrete time signal is attained when
f=__________.
A) ¼ B) 1/5 C) 1/3 D) ½
A) Restriking voltage
B) Arc voltage
C) Recovery voltage
D) Fault voltage
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
111. An electric motor developing a starting torque of 15 N-m, starts with a
load torque of 7 Nm on its shaft. If the acceleration at start is 2
rad/sec2, the moment of inertia of the system must be (neglecting
viscous and coulomb friction)
A) 0.25 Nm2 B) 0.25 kg-m2 C) 4 kg-m2 D) 4 N-m2
Solution :
112. The open – loop transfer function for the Bode’s magnitude plot is :
𝐾
A) G(s) H(s) = 𝑆 2 𝑆+5 (𝑆+50)
𝑲𝒔𝟐
B) G(s) H(s) = 𝑺+𝟓 (𝑺+𝟓𝟎)
𝐾𝑠
C) G(s) H(s) = 1+0.2𝑠 (1+0.02𝑠)
𝐾
D) G(s) H(s) = 𝑆 2 1+0.2𝑠 (1+0.02𝑠)
Solution :
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
114. The fourier transform of the signal δ(n) is :
A) e2j
B) 1
C) e-2j
D) 0
115.
A) 99.9 R, V2/9.9 R
B) 9.99 R, V2/99 R
C) 0.99 R, V2/99 R
D) 0.99 R, V2/9.9 R
∞
116. The summation of signal, 𝑛=−∞ 𝛿 (n – 2) sin2(n) is _________
A) 0 B) sin 2 C) 1 D) sin 4
Solution:
∞
𝑛=∞ 𝛿 (𝑛 − 2) sin 2 𝑛 =
= sin 4
117. The open – loop transfer function of a unity feedback control system is :
10
G(s) H(s) = 𝑆 𝑆+2 (𝑆+𝐾)
Here K is a Variable parameter. The system will be stable for all values of
A) K > 0
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
B) K > -2
C) K > 1.45
D) K > -1.55
Solution:
𝑠2 2+K 10
2+𝑘) 2𝑘−10
𝑠1 (2+k)2K>10
2+𝑘
4K+2k2-10>0
K>1.45
118. The absolute maximum and minimum values of f(x) = 𝑋 2/3 On the
interval [-2, 3] are
3 3
A) 3 4, 0 B) 𝟑 𝟗, 𝟎 C) 3 9, 4 D) 3 4, 9
120. The number of address lines required for an 8k-byte memory chip (8085)
is :
A) 10
B) 15
C) 18
D) 13
A) Mechanical resonance
B) Variation in the current ratio
C) Electrical resonance
D) Variation in current distribution
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
Ans(*)
122. A 50 Hz, 4 pole turbo alternator rated at 20 MVA, 13.2 kV has an inertia
constant H = 4 kW/kVA. The kinetic energy stored in the rotor at :
A) 40 MJ
B) 20 MJ
C) 80 MJ
D) 10 MJ
Solution :
K.E = GH = 20*4 = 80 MJ
124. In the region 0 < r < 0.5 m, in cylindrical co-ordinates, the current
density is
𝐴
𝐽 = 4.5 𝑒 −2𝑟 𝑎z 𝑚 2 and 𝐽 = 0 elsewhere. Use Amperes law and find 𝐻 .
1.125
A) 5 − 𝑒 −3𝑟 −2𝑟𝑒 −3𝑟 𝑎ф A/m
𝑟
𝟏.𝟏𝟐𝟓
B) 𝟏 − 𝒆−𝟐𝒓 −𝟐𝒓𝒆−𝟐𝒓 𝒂ф A/m
𝒓
1.125
C) 3 − 𝑒 −𝑟 −4𝑟𝑒 −3𝑟 𝑎ф A/m
𝑟2
1.125
D) 5 − 𝑒 −3𝑟 −4𝑟𝑒 −2𝑟 𝑎ф A/m
𝑟2
5𝑟 2 20
125. In the region r ≤ 2, 𝐷 = 4 𝑟 and r > 2, 𝐷 = 𝑟, in spherical co ordinates.
𝑟2
Find the charge density for r > 2.
A) 5/r
B) 5r
C) 5
D) 0
126. The steady state stability of the power system can be increased by :
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
127. A long line rated 100 MVA, 400 kV has ABCD constants as below :
A=D=0.8∟50 ; B=10 ∟400 ; C=0.001 ∟900 .
If receiving end voltage at no load is 400 kV, then sending end voltage is
_________
A) 400∟50 kV
B) 320 ∟𝟓𝟎 kV
C) 320 ∟−50 kV
D) 500 ∟−50 Kv
128. In a CRO, the component used to amplify the signal applied to the X-
plates is :
A) Trigger circuit
B) Attenuator
C) Horizontal amplifier
D) Vertical amplifier
129. A lightning arrester connected the line and earth in a power system :
A) Protects the terminal equipment against the travelling circuits
B) Protects the transmission line against direct lightning stroke
C) Reflects back the travelling wave approaching it
D) Suppresses high frequency oscillations in the line
1 : 𝑥 ≤1
130. The Fourier transform of f(x) = is :
0 : 𝑥 >1
𝜋 sin 2𝑠 𝟐 𝒔𝒊𝒏𝑺
A) . B) .
4 𝑆 𝝅 𝑺
𝜋 𝑠𝑖𝑛𝑆 𝜋 𝑠𝑖𝑛 2𝑆
C) . D) .
3 𝑆 3 𝑆
131. In 8085, the numbers 45H and 7EH are added. The resulting flag
settings will be as follows.
A) Both CY and AC are set
B) CY set AC reset
C) CY reset AC set
D) Both CY and AC reset
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
133. A 200 m radical line AB with resistance 0.2 Ω/km (go and return) is
loaded with 100 A at end B end 100 A at mid point C. If voltage at
sending end A is 200 V, then voltage at mid point C is :
A) 202 V
B) 198 V
C) 196 V
D) 197.5 V
135. A three phase delta connected squirrel cage induction motor has a
starting current Id and a starting torque Td at rated voltage. If the
starting current and starting torque while the motor is started through
star – delta started and auto – transformer (with 60% voltage) starter
alternatively are Iy, Ty and Iout Tout respectively, then.
Iy I Ty T
: out : 𝑇 : 𝑇out is equal to.
𝐼𝑑 𝑑𝐼 𝑑 𝑑
1 1 𝟏 𝟏
A) : 0.6 : : 0.6 B) : 0.6 : : 0.36
3 3 𝟑 𝟑
1 1 1 1
C) : 0.36 : : 0.36 D) : 0.36 : : 0.36
3 3 3 3
136. A 220 V, 50 Hz, transformer with 0.35 mm thick laminations has eddy
current loss of 120 watts which is two-third of the total loss at no-
load. If the transformer is built with 0.7 mm thick laminations and
is worked from 110 V, 25 Hz, then total no-load loss would be :
A) 150 W
B) 200 W
C) 510 W
D) 45 W
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
𝑆+2 2𝑆+2 𝟐𝑺+𝟒 2𝑆+4
A) B) C) D)
𝑆 2 + 2𝑠+4 𝑆 2 + 𝑠+2 𝑺𝟐 + 𝟐𝒔+𝟒 𝑆 2 + 𝑠+2
139. Bus impedance matrix for the network shown below is _______
pU impedance values are given.
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
A) (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
B) (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
C) (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
D) (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
(1+0.04𝑆)
143. A phase – lead network has its transfer function GC(s) = What is
(1+0.01𝑆)
the frequency at which the maximum phase – lead occurs?
A) 25 rad/sec
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
B) 75 rad/sec
C) 100 rad/sec
D) 50 rad/sec
1 2−𝑦
144. The change of order of integration in 0 𝑦
𝑥𝑦 𝑑𝑥 𝑑𝑦 is :
1 2−𝑥
A) 0 𝑥
𝑥𝑦 𝑑𝑦 𝑑𝑥
2 2−𝑥
B) 0 𝑥
𝑥𝑦 𝑑𝑦 𝑑𝑥
𝟏 𝒙 𝟐 𝟐−𝒙
C) 𝟎 𝟎
𝒙𝒚 𝒅𝒚 𝒅𝒙 + 𝟏 𝟎 𝒙𝒚 𝒅𝒚 𝒅𝒙
1 𝑥 2 2−𝑥
D) 0 0
𝑥𝑦 𝑑𝑦 𝑑𝑥 + 0 0
𝑥𝑦 𝑑𝑦 𝑑𝑥
𝑑𝑦
145. At the point x = 0.1, the solution of 𝑑𝑥 = x2 – y, y(0) = 1, using Taylor
series method, is given by :
A) 0.757216
B) 0.696912
C) 0.905125
D) 0.895215
146. The single phase line of 230 V and a three phase line of 400 V which
feed different domestic circuits and industrial loads represent
A) Primary distribution B) Secondary transmission
C) Primary subtransmission D) Secondary distribution
147.
In the circuit V1= 6 cos 𝜔𝑡 and V2= cos(𝜔𝑡 + 600 ). Find VA, If 𝜔=2 rad/sec.
148. Find the full scale output of a 4-bit DAC produces an output of 0.1 V for
a digital input 0001
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo
149. A chopper circuit is operating on TRC control mode at a frequency of 2
kHz of a 230 V dc supply. For output voltage of 170 V, the
conduction and blocking periods of a thyristor in each cycle are
respectively :
A) 0.386 ms and 0.114 ms B) 0.131 ms and 0.369 ms
C) 0.390 ms and 0.110 ms D) 0.369 ms and 0.131 ms
150. What is the time required to deliver a charge of 200 Ah through a single-
phase halfwave diode rectifier with an output current of 100 A rms
and with sinusoidal input voltage :
A) 4 Hours
B) 6.28 Hours
C) 2 Hours
D) 3.14 Hours
Online test series | BES materials | Classroom coaching for TNEB is available
Online ooo