HAL ELECTRICAL BRANCH QUESTION PAPER

HAL EXAM HELD AT HYDERABAD
Exam Held ON: 26-11-2006 

ELECTRICAL BRANCH

1) What is the distance between the EHV lines?
a)8m b)11m c)4m d)14m
2) At present how many HVDC lines are there in india?
a)none b)one c)two d)more than two
3) Where is the nuclear located in following places?
ans: i dont remember the answers, but one of them is thalcher(orissa)
4) What is the approximate peak overshoot for a unity feedback system with damping
factor 0.6?
a)10% b)5% c)15% d)20%
5) What is the distance between the EHV lines and earth?
a)8m b)11m c)18m d)15m
6) On no load in EHV lines what is the relation between receinving and sending end
voltage?
ans: receiving end voltage > sending end voltage
7) What is the surge impedance loading of 400kv line?
ans: 4002/400ohms =400watts
8) similar question with surge impedance given as 160 ohms
ans: 1000watts
9) If both the juctions of transistor are forward biased, in wat region transistor works
ans: saturation region
10) Where is the hydel power plant located in following places?
ans: I dont remember the places
11) self GMD is used in the calculation of_______
a) inductance only
b) inductance and capacitance
c) capacitance only
d) none
12) What is the GMD if the distance between the lines are 6m,6m,12m?
ans: 7.058m( approx)
13) 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: d
14) To avoid arcing connect sutable value of ________ in earthing.
a) capacitance
b) indunctance
c) resistance
d) susceptance
15)There are two to three questions based on Laplace and Inverse Laplace transforms
16)In the following type of conductors the corona is minimum
a) circular
b) stranded
c) helical
d) rectamgular
ans: c
17)When do two wattmeters show same value of opposite readings in two wattmeter
method
a) 300 lag
b) 600 lag
c) between 600 and 900 lag
d) zpf lag
ans: d
18) Schering bridge is used to measure
a) frequency
b) inductance
c) capacitance
d) mutual inductance
and: c
19) What is the value of resistance when both length and diameter of the wire are
doubled?
ans: halved
20) There is one questions asked on euler's formula..
21) What is the Laplace transform of unit ramp signal?
ans:1/s2
22) What happens to the value of inductance when self GMD is doubled?
23) At what frequency corona loss is more?
a) 50Hz
b) 60Hz
c)
d)
24) What is the largest rating of alternator manufactured in india?
a) 1000MW
b) 500MW
c) 1200MW
d) 250MW
ans:b
25) The response of an RLC circuit for impuse input?
a) exponentially raising
b) sinusoidal
c) exponential falling
d) parabolic
ans: c
26) What is the easier method for finding no. of poles in the right half of s-plane?
a) Niquist plot
b) R-H criterion
c) Root-Locus method
d) Polor plot
ans: b
27) How many no of poles located in the right half of s-plane for the characteristic
equation...
28) Burden of current transformers is measured in..
a) Watts
b) Volt Amperes
c) Ampere Hours
d) Joules
29)What is the gate used to get high output when all the inputs are low?
a) NOR
b) NAND
c) Ex-OR
d) Ex-NOR
ans: b
30) Large no of thyristors are used in HVDC transmission to improve______
a) current rating
b) voltage rating
c) Thyristers are available at high ratings
d)
31) What is the line current of a circuit when the current transformer of 1000:5 rating
measures 4Amperes?
ans: 800A
32) 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
33) How many no of flip-flops are required to get 16 bit counter?
34) _________is connected to reduce frequency errors in ammeter.
a) shunt capacitor
b) series inductance
c) shunt inductance
d)
35)What is the value of ripple factor in Half Wave Rectifier?
a) 1.11
b) 0.8
c) 1.21
d)
36)The principle used in megger?
a) electrostatic effect
b) magnetic effect
c) Induction effect
d)
37)In electrodynamometer type wattmeter the error is due to..
a) pressure coil inductance
b) pressure coil resistance
38) In the following locations where is hydal power plant is not located?
ans: i dont remember the places
39) In distribution lines_____
a) X/R<0.1
b) X/R>10
c) X/R>1
d) X/R<0.01
40) In EHV lines _____
a) X/R=10
b) X/R=100
c)
d)
41) What is the speed of 2 pole alternator at 50Hz frequency?
ans: 3000rpm
42) What is the equivalent decimal no of (624)8
43) What is the binary equivalent of 6.25
44) What is the value of A+AB+B¯ ( B bar)
ans: 1
45) What are the avg and rms values of full wave rectifier
ans: 2Vm/pie, Vm/21/2
46) There is one question based on rank of matrix
47) What is the equivalent of cos(wt+18.750)
a) sin(wt+71.250)
b) sin(wt-71.250)
c) sin(wt+18.250)
d) sin(wt-18.250)
48) The three harmonics will be in phace with each other?_____
a) 3,5,15
b) 2,4,6
c)
d)
ans: a
49) The line current will be equal to phase current in______
ans: delta connection
50) In windmills the frequent problems occur in______
a) mechanical system
b) blades
c) electrodynamic system
d) electric system
51) The machine used in windmills is______
a) alternator
b) induction generator
c)
d)
ans: b
52) Insulators in EHV lines are designed based on_____
a) switching voltages
b) peak voltages
c) corona
d) lightning voltages
ans: a
53) The value of restriking voltage depends on______
a) inductance of line
b) capacitance of line
c) both
d) none