Thursday, February 25, 2010

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

9 comments:

  1. answers are not given for all questions....... so, i find difficulty...

    ReplyDelete
  2. hey u did a great job but u didn't given answers will u plzzz send answers to my mail rajeshdigamarthi63@gmail.com this is email id

    ReplyDelete
  3. answers are not specified for every questions...

    ReplyDelete
  4. thanx........mr jagdish......great post dude.keep posting ...

    ReplyDelete
  5. Thank you.. It was very helpful..

    ReplyDelete

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