POWER SYSTEMS

POWER SYSTEMS

Q.A wave will not experience any reflection when impedance of line is equal to

a surge impedance
b load impedance
c >surge impedance
d
Ans: surge impedance

Q.if the length of a wire is increased what happens to its resistance

a increases linearly
b increases exponentially

Q.for a current carrying coil if the current is doubled then the field strength is

a doubled
b halved
c increased 4 times

Q.a capacitor of 10 micro farads is charged thruogh a resistor of 10 ohms and a 6 V battery. Calculate the time taken by the capacitor to charge to its maxm value.

a 1 sec
b 100 sec
c 0.1 sec
d 10 sec

Q.what current is drawn by a 10 W lamp connected to a 220 V,60 Hz source.

a 1 A
b 0.5 A
c 0.045 A
d 0.01 A

Ans: 0.045

Q.At present how many HVDC lines are there in india?

a none
b one
c two
d more than two

Q.What is the distance between the EHV lines and earth?

a 8m
b 11m
c 18m
d 15m

Q.On no load in EHV lines what is the relation between receinving and sending end voltage?

a receiving end voltage > sending end voltage
b receiving end voltage < sending end voltage
c receiving end voltage = sending end voltage
d none

Ans: receiving end voltage > sending end voltage

Q.What is the surge impedance loading of 400kv line?

a 400 MW
b 400 KW
c 1600 MW
d 1600 KW

Ans: 400 MW

Q.What is the surge impedance loading of 400kv line with surge impedance given as 160 ohms

a 1000 MW
b 1000 KW
c 256 MW
d 256 KW

Ans: 1000 MW

Q.Where is the hydel power plant located in following places?

a Raamagundam
b Tarapur
c Kalpakam
d Srisailam

Ans: Raamagundam

Q.self GMD is used in the calculation of_______

a inductance only
b inductance and capacitance
c capacitance only
d none

Ans: inductance only

Q.What is the GMD if the distance between the lines are 6m,6m,12m?

a 7.55m
b 6m
c 12m
d 8.56m

Ans: 7.55m

Q.Zero sequence currents doesn't exist in the following fault

a L-G
b L-L
c L-L-G
d L-L-L-G

Ans: L-L


Q.To avoid arcing connect sutable value of ________ in earthing.

a capacitance
b indunctance
c resistance
d susceptance

Ans: indunctance

Q.In the following type of conductors the corona is minimum

a circular
b stranded
c helical
d rectamgular

Ans:circular

Q.At what frequency corona loss is more?

a 50Hz
b 60Hz
c 25Hz
d 100Hz

Ans: 100HZ

Q.What is the line current of a circuit when the current transformer of 1000:5 rating measures 4Amperes?

a 5000 A
b 1000 A
c 400 A
d 800A

Ans: 800A

Q.If the time delay of relay with TMS setting 0.1 is 10 sec, then what is the time delaty when the TMS setting is changed to 0.5

a 2 sec
b 20 sec
c 100 sec
d 5 sec

Ans: 5 sec

Q.In distribution lines_____

a X/R<0.1
b X/R>10
c X/R<1
d X/R<0.01

Ans: X/R<1

Q.In EHV lines _____

a X/R=10
b X/R=100
c X/R>3
d X/R<3

Ans: X/R>3

Q.In wind mills the frequent problems occur in______

a mechanical system
b blades
c electrodynamic system
d electric system

Q.The machine used in windmills is______

a Alternator
b Induction generator
c Synchronous generator
d All

Ans: Induction generator

Q.Insulators in EHV lines are designed based on_____

a switching voltages
b peak voltages
c corona
d lightning voltages

Ans: switching voltages

Q.The value of restriking voltage depends on______

a inductance of line
b capacitance of line
c both
d none

Ans: both

Q.HRC fuse and circuit-breaker combination is used CB operates for

a low over-load currents
b high over-load currents
c combination is never used

Ans: low over-load currents

Q. SIL of 400 KV lines is

a 400 MW
b 400 KW
c 1600 MW
d 1600 KW

Ans: 400 MW

Q. SIL of 100 KV cable is

a 400 MW
b 400 KW
c 250 MW
d 250 KW

Ans: 250 MW

Q.reflection coefficent of current of an open ended line.

a 1
b -1
c 2
d -2

Ans: -1

Q.Positive sequence terminal voltage is zero in

a L-L
b L-L-G
c L-G
d L-L-L

Ans: L-L-L

Q.Most economical load in underground cable is

a less than surge impedance
b equal to surge impdance
c more than surge impedence
d any load

Ans: less than surge impedance

Q.The impedance of a lossless transmission line is

a v(L/C)
b L/C
c 1/vLC
d 1/LC

Q.Zsc =100? Zoc =1? then Zo is

a 1
b 10
c 100
d 0.1

Ans: 10

Q.Normal PH value of water used in thermal power station is

a 7
b 2
c 5
d Slightly >7

Ans: Slightly >7

Q.Maximum power transfer through line V1= 110 kv, V2= 100kv, X=22 ohm is

a 500 MW
b 500 KW
c 250 MW
d 250 KW

Ans: 500 MW

Q.Which type of power plant requires maximum expenditure

a Hydel power plants
b Nuclear power plants
c Thermal power plants
d Gas based power plants

Q.Base load of a power station stands for

a 2-4 hours/day
b 4-8 hours/day
c 8-12 hours/day
d 12-24hours/day

Ans: 12-24hours/day

Q.A wire is placed on the top of a transmission line to protect from

a surge high voltage
b Direct lightning strocks
c indirect lightnin strocks
d Switching over voltages

Ans: Direct lightning strocks

Q.A wire is placed on the top of a transmission line acts as

a acts as a phase wire
b acts as neutral
c acts as a transmission wire
d acts as ground wire

Ans: acts as ground wire

ANALOG ELECTRONICS

Q. Power diode is generally made from
a) Silicon
b) Germanium
c) Both
d) None of these

Q. When the both junction of NPN diode is reverse biased, then the diode is in which mode
a) Active
b) Cutoff
c) Saturation
d) inverted

Q. Which transistor mode gives the inverted output
a) Common Emitter
b) Common Base
c) Common Collector
d) None of these

Q. Which coupling gives the higher gain in case of amplifier
a) Capacitor coupling
b) Impedance coupling
c) Transformercoupling

Q. Which distortion is least objectionable in audio amplification
a) Phase
b) Frequency
c) Harmonic
d) Intermediation

Q. A narrow band amplifier has a band pass nearly…………of central frequency
a) 33.3%
b) 10%
c) 50%

Q. Phase shift oscillator consists
a) RL
b) RC
c) RLC

Q. Multivibrater Produces
a) Sine wave
b) Square wave
c) Smooth wave
d) sawtooth

Q. Convert the 101101 Binary number into octal no
a) 65
b) 55
c) 51
d) 45

Ans: 55

Q. 10 in BCD
a) 10100
b) 1100
c) 010111
d) None of these

Ans: None of these

Q. Which PNP device has a terminal for synchronizing purpose
a) SCS
b) Triac
c) Diac
d) SUS

Q. Addition of indium in semiconductor crystal makes
a) PNP
b) NPN

Q. Free electron exists in which band
a) 1
b) 2
c) 3
d) Conduction band

Q. Ripple factor of half wave rectifier
a) 1.21
b) 0.48
c) 0.5

Q. Transistor that can be used in enhancement mode
a) NPN
b) UJT
c) JFET
d) MOSFET

Q. Following contributes to harmonic distortion in Amplifier
a) +Ve feedback
b) –Ve feedback
c) Defective active device

Q. High cutoff frequency
a) CB
b) CC
c) CE

Q. Which is used as data selector?
a) Encoder
b) Decoder
c) modulator
d) Demodulator

Q. Read write capable memory
a) RAM
b) ROM
c) Both
d) None of these

Q.the radix or base of hexadecimal number system is -----------
a) 8
b) 16
c) 5
d) none of these

Ans: 16

Q.the no of 1’s in the binary representation of the expression 162*9+162*7+16*5+3 are
a) 10
b) 23
c) 6
d) 4

Q. the no of latches in F/F are -------
a) 1
b) 2
c) 3
d) 4

Q.how many flip-flops are required to construct Mod -12 counter
a) 5
b) 4
c) 12
d) none

Ans: 4

Q. which logic gate has the output is compliment of its input ----------
a) OR
b) AND
c) NOT
d) X-OR

Ans: NOT

Q.no.of 2-input multiplexers needed to construct a 210 input multiplexer…….
a) 12
b) 31
c) 20
d) 16

Q.By adding inverters to the inputs and output of a AND gate we can obtain ……………
a) OR
b) AND
c) NOT
d) X-OR

Ans: X-OR

Q.how many NAND gates are needed to realize OR gate --------------
a) 1
b) 2
c) 3
d) 4

Ans: 3

Q.which is the first integrated logic family ---------------
a) RTL
b) DTL
c) TTL
d) none of these

Q. Which logic gate has output high if and only if all inputs are low ---------?
a) NOR
b) NAND
c) X-NOR
d) AND

Ans: NAND

Q.According to Boolean algebra 1+A+B+C =
a) A
b) A+B+C
c) 1
d) none of these

Ans: 1

Q. If a=0x6db7 and b=0x2ae9 then what is the value of a”b--------------
a) binary number for 1001.1101?
b) decimal number for 19?
c) excess-3 code for 29?

Q.what is the value of A'+1 ?
a) A
b) A'
c) 1
d) none of these

Ans: 1

Q.2 in 4 bit number one bit indicates sign of the number then the locations are from
a) -8 to 8
b) -7 to 7
c) -16 to 16
d) None

Q.Avalanche photo diode is used when compared to PIN diode bcz
a)larger band width
b)high sensitivity
C)-------
d)--------

Q.some non zero DC voltage is to RC low pass circuit then the DC voltage in the output contains
a) Same as in input
b) Higher than input
c) Zero
d) Slightly increases

Q.if the output of the gate is always high then the gates applied to this logic are 0,0
a) NAND and EX-NOR
b) NAND and NOR
c) AND and X-NOR
d) OR and XOR

Ans:a

Q.Thermal Run away is not possible in FET bcz the flow of
a)minority careers
b)Transconductance
c)_____
d)none

Ans : minority careers

Q.which of the following is/are true about 1's and 2's compements:
i)In 1's complement form. 0 has two representations
ii)in 1's complement, the magnitude of lowest number is equal to the magnitude of highest number
iii)In 2's complement, 0 has two representations

a) i only
b) i and ii
c) iii only
d) all of these

Q.In the hybrid parameter model of a transistor reverse transfer voltage ratio and forward transfer current ratio are respectively given by:
a) h11 and h21
b) h12 and h11
c) h21 and h11
d) None of these

Q.The largest negative no can be represented with 8 bits in 2's compliment representation?
a)-256
b)-255
c)-127
d)-128

Ans: -128

Q. How many NAND gates required to implement AB+CD+EF
a) 1
b) 2
c) 3
d) 4

Ans: 4

Q. Transparent latch is seen in which type of flip flop
a) SR FF
b) D FF
c) JK FF
d) D FF

Ans: D FF

Q. Odd parity generator uses which logic?
a) Digital
b) Analog
c) Sequential
d) none

Q. Which type of ADC is fastest?
a) SARC
b) Counter type
c) Intigrated type
d) Flash

ANS: Flash/Parallel

Q. Which one of the following is fastest read/writable memory?
a) PROM
b) EEPROM
c) Flash
d) none

Ans: Flash

8. In array programming which one is used
a) SISD
b) PISD
c) MISD
d) None

Q.Which one of the following has high I/p impedance
a) CC
b) CB
c) CE
d) None

Q. The maximum time allowed time for each flip flop for a mod 10 synchronous counter if each flip flop delay is 25ns.
a) 25 ns
b) 50 ns
c) 100 ns
d) none

Q. The resolution for a DAC is given by 0.4% then no. of bits of DAC is
a) 8- bits
b) 16- bits
c) 32- bits
d) none

Ans: 8- bits

41) The chip capacity is 256 bits, then the no.of chips required to build 1024 B memory Is
a) 32
b) 16
c) 15
d) 4

Q. Which of the following are correct?
1)A flip-flop is used to store 1-bit of information
2)Race around condition occurs in JK flip flop when both the inputs are 1
3)Master slave flip flop is used to store 2 bits of information
4)A transparent latch consists of a D- flip flop

a) 1,2,3
b) 1,3,4
c) 1,2,4
d) 2,3,4

Ans: 1,2,4

Q. output resistance of ideal OP AMP is
a) 0
b) 1
c) infinite
d) very high

ANS: 0

Q. CMRR of an OP AMP is given as 80db and Ad is 20000.Value of Acm will be
a) 4
b) 8
c) 2
d) 1

Ans: 2

Q.Si,Ge lie in ........block of periodic table
a) III
b) V
c) IV A
d) IV B

Ans: IV A

Q.to obtain 10 mV resolution on 5 V range how many bit DAC is to be used
a) 4
b) 8
c) 16
d) 32

Q.% resolution of a 10 bit ADC
a) 1.588%
b) 0.392%
c) 0.0978%
d) 0.0244%

Ans: 0.0978%

Q.Efficiency of half wave rectifier
a) 45%
b) 50%
c) 86%
d) 100%

Ans: 45%