A.C. TRANSMISSION AND DISTRIBUTION

Objective Questions

Short notes

Objective questions (Answers are given below)

With same maximum voltage between conductors,
the ratio of copper volumes in 3-phase, 3-
wire system and 1-phase, 2-wire system is
(a) 4/3 (b) 3/4
(c) 5/3 (d) 3/5
The volume of copper required for an a.c. transmission
line is inversely proportional to
(a) current (b) voltage
(c) power factor (d) both (b) and (c)
(e) both (a) and (c).
For a.c. transmission lines less than 80 km in
length, it is usual to lump the line capacitance
at
(a) the receiving end
(b) the sending end
(c) the mid-point
(d) any convenient point.
Corona occurs between two transmission wires
when they
(a) are closely-spaced
(b) are widely-spaced
(c) have high potential difference
(d) carry d.c. power.
The only advantage of corona is that it
(a) makes line current non-sinusoidal
(b) works as a safety-valve for surges
(c) betrays its presence by hissing sound
(d) produces a pleasing luminous glow.
The sag produced in the conductor of a transmission
wire depends on
(a) weight of the conductor per unit length
(b) tension in the conductor
(c) length of the conductor
(d) all of the above
(e) none of the above.
Suspension insulators are used when transmission
voltage is
(a) high (b) low
(c) fluctuating (d) steady
The string efficiency of suspension insulators
can be increased by
(a) providing a guard ring
(b) grading the insulators

An interconnector between two generating stations
facilitates to
(a) keep their voltage constant
(b) run them in parallel
(c) transfer power in either direction
(d) both (b) & (c)
The effective disruptive critical voltage of a
transmission line does NOT depend on
(a) irregularity factor
(b) conductor radius
(c) distance between conductors
(d) material of the conductors.
By which of the following systems electric
power may be transmitted?
(a) Overhead system
(b) Underground system
(c) Both (a) and (b)
(d) None of the above
……. are the conductors, which cannect the
consumer’s terminals to the distribution
(a) Distributors
(b) Service mains
(c) Feeders
(d) None of the above
The underground system cannot be operated
above
(a) 440 V (b) 11 kV
(c) 33 kV (d) 66 kV
Overhead system can be designed for
operation upto
(a) 11 kV (b) 33 kV
(c) 66 kV (d) 400 kV
If variable part of annual cost on account of
interest and depreciation on the capital outlay
is equal to the annual cost of electrical energy
wasted in the conductors, the total annual cost
will be minimum and the corresponding size
of conductor will be most economical. This
statement is known as
(a) Kelvin’s law (b) Ohm’s law
(c) Kirchhoff’s law (d) Faraday’s law
(e) none of the above
The wooden poles well impregnated with
creosite oil or any preservative compound have
life
(a) from 2 to 5 years
(b) 10 to 15 years
(c) 25 to 30 years
(d) 60 to 70 years
Which of the following materials is not used
for transmission and distribution of electrical
power?
(a) Copper
(b) Aluminium
(c) Steel
(d) Tungsten
Galvanised steel wire is generally used as
(a) stay wire
(b) earth wire
(c) structural components
(d) all of the above
The usual spans with R.C.C. poles are
(a) 40–50 metres
(b) 60–100 metres
(c) 80–100 metres
(d) 300–500 metres
The corona is considerably affected by which
of the following?
(a) Size of the conductor
(b) Shape of the conductor
(c) Surface condition of the conductor
(d) All of the above
Which of the following are the constants of the
transmission lines?
(a) Resistance
(b) Inductance
(c) Capacitance
(d) All of the above
%age regulation of a transmission line is given
by
(a)
V V
V
R S
R
2
−
× 100
(b)
V V
V
S R
R
−
× 100
(c)
V V
V
S R
S
−
× 100
(d)
V V
V
S R
R
2
−
× 100
where VS and VR are the voltages at the
sending end and receiving and respectively.
The phenomenon of rise in voltage at the
receiving end of the open-circuited or lightly
loaded line is called the
(a) Seeback effect
(b) Ferranti effect
(c) Raman effect
(d) none of the above

The square root of the ratio of line impedance
and shunt admittance is called the
(a) surge impedance of the line
(b) conductance of the line
(c) regulation of the line
(d) none of the above
Which of the following is the demerit of a
‘constant voltage transmission system’?
(a) Increase of short-circuit current of the
system
(b) Availability of steady voltage at all loads
at the line terminals
(c) Possibility of better protection for the line
due to possible use of higher terminal
reactances
(d) Improvement of power factor at times of
moderate and heavy loads
(e) Possibility of carrying increased power
for a given conductor size in case of longdistance
heavy power transmission
Low voltage cables are meant for use up to
(a) 1.1 kV
(b) 3.3 kV
(c) 6.6 kV
(d) 11 kV
The operating voltage of high voltage cables
is upto
(a) 1.1 kV
(b) 3.3 kV
(c) 6.6 kV
(d) 11 kV
The operating voltage of supertension cables
is upto
(a) 3.3 kV
(b) 6.6 kV
(c) 11 kV
(d) 33 kV
The operating voltage of extra high tension
cables is upto
(a) 6.6 kV
(b) 11 kV
(c) 33 kV
(d) 66 kV
(e) 132 kV
Which of the following methods is used for
laying of underground cables?
(a) Direct laying
(b) Draw-in-system
(c) Solid system
(d) All of the above
Which of the following is the source of heat
generation in the cables?
(a) Dielectric losses in cable insulation
(b) I2R losses in the conductor
(c) Losses in the metallic sheathings and
armourings
(d) All of the above
Due to which of the following reasons the
cables should not be operated too hot?
(a) The oil may loose its viscosity and it may
start drawing off from higher levels
(b) Expansion of the oil may cause the sheath
to burst
(c) Unequal expansion may create voids in
the insulation which will lead to ionization
(d) The thermal instability may rise due to
the rapid increase of dielectric losses with
temperature
Which of the following D.C. distribution
system is the simplest and lowest in first cost?
(a) Radial system
(b) Ring system
(c) Inter-connected system
(d) Non of the above
A booster is a
(a) series wound generator
(b) shunt wound generator
(c) synchronous generator
(d) none of the above
Besides a method of trial and error, which of
the following methods is employed for
solution of network problems in interconnected
system?
(a) Circulating current method
(b) Thevenin’s theorem
(c) Superposition of currents
(d) direct application of Kirchhoff’s laws
(e) All of the above
Which of the following faults is most likely to
occur in cables?
(a) Cross or short-circuit fault
(b) Open circuit fault
(c) Breakdown of cable insulation
(d) all of the above
The cause of damage to the lead sheath of a
cable is
(a) crystallisation of the lead through
vibration
(b) chemical action on the lead when
(c) mechanical damage
(d) all of the above
The voltage of the single phase supply to
residential consumers is
(a) 110 V
(b) 210 V
(c) 230 V
(d) 400 V
Most of the high voltage transmission lines in
India are
(a) underground
(b) overhead

The distributors for residential areas are
(a) single phase
(b) three-phase three wire
(c) three-phase four wire
(d) non of the above
The conductors of the overhead lines are
(a) solid
(b) stranded
(c) both solid and stranded
(d) none of the above
High voltage transmission lines use
(a) suspension insulators
(b) pin insulators
(c) both (a) and (b)
(d) none of the above
Multicore cables generally use
(a) square conductors
(b) circular conductors
(c) rectangular conductors
(d) sector-shaped conductors
(e) none of the above
Distributio lines in India generally use
(a) wooden poles
(b) R.C.C. poles
(c) steel towers
(d) none of the above
The material commonly used for insulation in
high voltage cables is
(a) lead
(b) paper
(c) rubber
(d) none of the above
The loads on distributors systems are generally
(a) balanced
(b) unbalanced
(c) either of the above
(d) none of the above
The power factor of industrial loads is
generally
(a) unity
(b) lagging
(c) leading
(d) zero
Overhead lines generally use
(a) copper conductors
(b) all aluminium conductors
(c) A.C.S.R. conductors
(d) none of these
In transmission lines the cross-arms are made
of
(a) copper
(b) wood
(c) R.C.C.
(d) steel
The material generally used for armour of high
voltage cables is
(a) aluminium
(b) steel
(c) brass
(d) copper
Transmission line insulators are made of
(a) glass
(b) porcelain
(c) iron
(d) P.V.C.
The material commonly used for sheaths of
underground cables is
(a) lead
(b) rubber
(c) copper
(d) iron
The minimum clearance between the ground
and a 220 kV line is about
(a) 4.3 m
(b) 5.5 m
(c) 7.0 m
(d) 10.5 m
The spacing between phase conductors of a
220 kV line is approximately equal to
(a) 2 m
(b) 3.5 m
(c) 6 m
(d) 8.5 m
Large industrial consumers are supplied
electrical energy at
(a) 400 V
(b) 11 kV
(c) 66 kV
(d) 400 kV
In a D.C. 3-wire distribution system, balancer
fields are cross-connected in order to
(a) boost the generated voltage
(b) balance loads on both sides of the neutral
(c) make both machines run as unloaded
motors
(d) equalize voltages on the positive and
negative outers
In a D.C. 3-wire distributor using balancers
and having unequal loads on the two sides
(a) both balancers run as generators
(b) both balancers run as motors
(c) balancer connected to lightly-loaded side
runs as a motor
(d) balancer connected to heavily-loaded side
runs as a motor
Transmitted power remaining the same, if
supply voltae of a D.C. 2-wire feeder is
increased 100 percent, saving in copper is

(a) 25 percent
(b) 50 percent
(c) 75 percent
(d) 100 percent

A uniformly-loaded D.C. distributor is fed at
both ends with equal voltages. As compared
to a similar distributor fed at one end only, the
drop at a middle point is
(a) one-fourth
(b) one-third
(c) one-half
(d) twice
(e) none of the above
As compared to a 2-wire D.C. distributor, a
3-wire distributor with same maximum
voltage to earth uses only
(a) 31.25 percent of copper
(b) 33.3 percent of copper
(c) 66.7 percent of copper
(d) 125 percent of copper
Which of the following is usually not the
generating voltage?
(a) 6.6 kV
(b) 8.8 kV
(c) 11 kV
(d) 13.2 kV
For an overhead line, the surge impedance is
taken as
(a) 20–40 ohms
(b) 70–80 ohms
(c) 100–200 ohms
(d) 500–1000 ohms
(e) none of the above
The presence of ozone due to corona is
harmful because it
(a) reduces power factor
(b) corrodes the material
(c) gives odour
(d) transfer energy to the ground
(e) none of the above
A feeder, in a transmission system, feeds power
to
(a) distributors
(b) generating stations
(c) service mains
(d) all of the above
The power transmitted will be maximum when
(a) corona losses are minimum
(b) reactance is high
(c) sending end voltage is more
(d) receiving end voltage is more
A 3-phase 4 wire system is commonly used on
(a) primary transmission
(b) secondary transmission
(c) primary distribution
(d) secondary distribution
Which of the following materials is used for
overhead transmission lines?
(a) Steel cored aluminium
(b) Galvanised steel
(c) Cadmium copper
(d) Any of the above
Which of the following is not a constituent for
making porcelain insulators?
(a) Quartz
(b) Kaolin
(c) Felspar
(d) Silica
There is a greater possibility of occurence of
corona during
(a) dry weather
(b) winter
(c) summer heat
(d) humid weather
(e) none of the above
Which of the following relays is used on long
transmission lines?
(a) Impedance realy
(b) Mho’s relay
(c) Reactance relay
(d) None of the above
The steel used in steel cored conductors is
usually
(a) alloy steel
(b) stainless steel
(c) mild steel
(d) high speed steel
(e) all of the above
Which of the following distribution system is
more reliable?
(a) Radial system
(b) Tree system
(c) Ring main system
(d) All are equally reliable
Which of the followin characteristics should
the line supports for transmission lines possess?
(a) Low cost
(b) High mechanical strength
(c) Longer life
(d) All of the above
Transmission voltage of 11 kV is normally
used for distance upto
(a) 20–25 km
(b) 40–50 km
(c) 60–70 km
(d) 80–100 km
which of the following regulations is
considered best?
(a) 50%
(b) 20% (c) 10 (d) 2%

Skin effect is proportional to
(a) (conductor diameter)4
(b) (conductor diameter)3
(c) (conductor diameter)2
(d) (conductor diameter)1/2
(e) none of the above
A conductor, due to sag between two supports,
takes the form of
(a) semi-circle
(b) triangle
(c) ellipse
(d) catenary
In A.C.S.R. conductors, the insulation between
aluminium and steel conductors is
(a) insulin
(b) bitumen
(c) varnish
(d) no insulation is required
Which of the following bus-bar schemes has
the lowest cost?
(a) Ring bus-bar scheme
(b) Single bus-bar scheme
(c) Breaker and a hlaf scheme
(d) Main and transfer scheme
Owing to skin effect
(a) current flows through the half crosssection
of the conductor
(b) portion of the conductor near the surface
carries more current and core of the
conductor carries less current
(c) portion of the conductor near the surface
carries less current and core of the
conductor carries more current
(d) none of the above
By which of the following methods string
efficiency can be improved?
(a) Using a guard ring
(b) Grading the insulator
(c) Using long cross arm
(d) Any of the above
(e) None of the above
In aluminium conductors, steel core is
provided to
(a) compensate for skin effect
(b) neutralise proximity effect
(c) reduce line inductance
(d) increase the tensile strength
By which of the following a bus-bar is rated?
(a) Current only
(b) Current and voltage
(c) Current, voltage and frequency
(d) Current, voltage, frequency and short time
current
A circuit is disconnected by isolators when
(a) line is energize
(b) there is no current in the line
(c) line is on full load
(d) circuit breaker is not open
For which of the following equipment current
rating is not necessary?
(a) Circuit breakers
(b) Isolators
(c) Load break switch
(d) Circuit breakers and load break switches
In a substation the following equipment is not
installed
(a) exciters
(b) series capacitors
(c) shunt reactors
(d) voltage transformers
Corona usuall occurs when the electrostatic
stress in air around the conductor exceeds
(a) 6.6 kV (r.m.s. value)/cm
(b) 11 kV (r.m.s. value)/cm
(c) 22 kV (maximum value)/cm
(d) 30 kV (maximum value)/cm
The voltage drop, for constant voltage
transmission is compensated by installing
(a) inductors
(b) capacitors
(c) synchronous motors
(d) all of above
(e) none of the above
The use of strain type insulators is made where
the conductors are
(a) dead ended
(b) at intermediate anchor towers
(c) any of the above
(d) none of the above
The current drawn by the line due to corona
losses is
(a) non-sinusoidal
(b) sinusoidal
(c) triangular
(d) square
Pin type insulators are generally not used for
voltages beyond
(a) 1 kV
(b) 11 kV
(c) 22 kV
(d) 33 kV
Aluminium has a specific gravity of
(a) 1.5
(b) 2.7
(c) 4.2
(d) 7.8
For transmission of power over a distance of
200 km, the transmission voltage should be

(a) 132 kV
(b) 66 kV
(c) 33 kV
(d) 11 kV

For aluminium, as compared to copper, all the
following factors have higher values except
(a) specific volume
(b) electrical conductivity
(c) co-efficient of linear expansion
(d) resistance per unit length for same crosssection
Which of the following equipment, for
regulating the voltage in distribution feeder,
will be most economical?
(a) Static condenser
(b) Synchronous condenser
(c) The changing transformer
(d) Booster transformer
In a tap changing transformer, the tappings are
provided on
(a) primary winding
(b) secondary winding
(c) high voltage winding
(d) any of the above
Constant voltage transmission entails the
following disadvantage
(a) large conductor area is required for same
power transmission
(b) short-circuit current of the system is
increased
(c) either of the above
(d) none of the above
On which of the following factors skin effect
depends?
(a) Frequency of the current
(b) Size of the conductor
(c) Resistivity of the conductor material
(d) All of the above
The effect of corona can be detected by
(a) presence of zone detected by odour
(b) hissing sound
(c) faint luminous glow of bluish colour
(d) all of the above
for transmission of power over a distance of
500 km, the transmission voltage should be in
the range
(a) 150 to 220 kV
(b) 100 to 120 kV
(c) 60 to 100 kV
(d) 20 to 50 kV
In the analysis of which of the following lines
shunt capacitance is neglected?
(a) Short transmission lines
(b) Medium transmission lines
(c) Long transmission lines
(d) Modium as well as long transmission lines
When the interconnector between two stations
has large reactance
(a) the transfer of power will take place with
voltage fluctuation and noise
(b) the transfer of power will take place with
least loss
(c) the stations will fall out of step because
of large angular displacement between the
stations
(d) none of the above
The frequency of voltage generated, in case of
generators, can be increased by
(a) using reactors
(b) increasing the load
(c) adjusting the governor
(d) reducing the terminal voltage
(e) none of the above
When an alternator connected to the bus-bar
is shut down the bus-bar voltage will
(a) fall
(b) rise
(c) remain uncharged
(d) none of the above
The angular displacement between two
interconnected stations is mainly due to
(a) armature reactance of both alternators
(b) reactance of the interconnector
(c) synchronous reactance of both the
alternators
(d) all of the above
Electro-mechanical voltage regulators are
generally used in
(a) reactors
(b) generators
(c) transformers
(d) all of the above
Series capacitors on transmission lines are of
little use when the load VAR requirement is
(a) large
(b) small
(c) fluctuating
(d) any of the above
The voltage regulation in magnetic amplifier
type voltage regulator is effected by
(a) electromagnetic induction
(b) varying the resistance
(c) varying the reactance
(d) variable transformer
when a conductor carries more current on the
surface as compared to core, it is due to
(a) permeability variation
(b) corona
(c) skin effect
(d) unsymmetrical fault

The following system is not generally used
(a) 1-phase 3 wire
(b) 1-phase 4 wire
(c) 3-phase 3 wire
(d) 3-phase 4 wire
The skin effect of a conductor will reduce as
the
(a) resistivity of conductor material increases
(b) permeability of conductor material
increases
(c) diameter increases
(d) frequency increases
When a live conductor of public electric wupply
breaks down and touches the earth which of
the following will happen?
(a) Current will flow to earth
(b) Supply voltage will drop
(c) Supply voltage will increase
(d) No current will flow in the conductor
310 km line is considered as
(a) a long line
(b) a medium line
(c) a short line
(d) any of the above
The conductors are bundled primarily to
(a) increase reactance
(b) reduce reactance
(c) reduce ratio interference
(d) none of the above
The surge impedance in a transmission line
having negligible resistance is given as
(a) LC
(b) L/C
(c) 1/LC
(d) L + C
(e) none of the above
The top most conductor in a high transmission
line is
(a) earth conductor
(b) R-phase conductor
(c) Y-phase conductor
(d) B-phase conductor
In A.C.S.R. conductor the function of steel is
to
(a) provide additional mechanical strength
(b) prevent corona
(c) take care of surges
(d) reduce inductance and subsequently
improve power factor
In transmission and distribution system the
permissible voltage variation is
(a) ±1 percent
(b) ± 10 percent
(c) ± 20 percent
(d) ± 30 percent
(e) none of the above
By which of the following methods voltage of
transmission can be regulated?
(a) use of series capacitors to neutralies
the effect of series reactance
(b) Switching in shunt capacitors at the
receiving end during have loads
(c) Use of tap changing transformers
(d) Any of the above methods
Which of the following distribution systems is
the most economical?
(a) A.C. 1-phase system
(b) A.C. 3-phase 3 wire system
(c) A.C. 3-phase 4 wire system
(d) Direct current system
Which of the following is the main advantage
of A.C. transmission system over D.C.
transmission system?
(a) Less instability problem
(b) Less insulation problems
(c) Easy transformation
(d) Less losses in transmission over long
distances
A tap changing transformer is used to
(a) supply low voltage current for instruments
(b) step up the voltage
(c) step down the voltage
(d) step up as well as step down the voltage
Which of the following bar schemes is the
most expensive?
(a) Double bus-bar double breaker
(b) Ringbus-bar scheme
(c) Single bus-bar scheme
(d) Main and transfer scheme
By which of the following methods the
protection agains direct lightning strokes and
high voltage sweep waves is provided?
(a) Lightening arresters
(b) Ground wire
(c) Lightening arresters and ground wires
(d) Earthing of neutral
(d) None of the above
In which of the following voltage regulators
the effect of dead zero is found?
(a) Electromagnetic type
(b) Magnetic amplifier
(c) Electronic type using integrated circuits
(e) all of the above
Corona results in

(a) radio interference
(b) power factor improvement
(c) better regulation
(d) none of the above

Which of the following has least effect on
corona?
(a) Atmospheric temperature
(b) Number of ions
(c) Size and charge per ion
(d) Mean free path
In context of corona, if the conductors are
polished and smooth, which of the following
statements is correct?
(a) Hissing sound will be more intense
(b) Power loss will be least
(c) Corona glow will be uniform along the
length of the conductor
(d) Corona glow will not occur
Power loss due to corona is not directly
proportional to
(a) spacing between conductors
(b) supply voltage frequency
(c) phase-neutral voltage
(d) all of the above
Poles which carry transformers are usually
(a) circular
(b) I-type
(c) A-type
(d) H-type
(e) none of the above
Out of the following which type of poles are
bulky?
(a) Transmission towers
(b) Concrete poles
(c) Tubular steel poles
(d) Wooden poles
The effect of ice on transmission line
conductors is to increase the
(a) transmission losses
(b) weight of the conductor
(c) tendency for corona
(d) resistance to flow of current
If the height of transmission tower is increased
(a) the line capacitance will decrease but line
inductance will remain uncharged
(b) the line capacitance and inductance will
not change
(c) the line capacitance will increase but line
inductance will decrease
(d) the line capacitance will decrease and line
inductance will increase
If staring efficiency is 100 percent it means
that
(a) potential across each disc is zero
(b) potential across each disc is same
(c) one of the insulator discs is shorted
(d) none of the above
In a 70/6 A.C.S.R. conductor there are
(a) 35 aluminium conductors and 3 steel
conductors
(b) 70 aluminium conductors and 6 steel
conductors
(c) 70 steel conductors and 6 aluminium
conductors
(d) none of the above
On which of the following does the size of a
feeder depend?
(a) Voltage drop
(b) Voltage
(c) Frequency
(d) Current carrying capacity
Which of the following are connected by the
service mains?
(a) Transformer and earth
(b) Distributor and relay system
(c) Distributor and consumer terminals
(d) Distributor and transformer
In the design of a distributor which of the
following is the major consideration?
(a) Voltage drop
(b) Current carrying capacity
(c) Frequency
(d) kVA of system
(e) None of the above
In a distribution system major cost is that of
(a) earthing system
(b) distribution transformer
(c) conductors
(d) meters
A booster is connected in
(a) parallel with earth connection
(b) parallel with the feeder
(c) series with the feeder
(d) series with earth connection
With which of the following are step-up
substations associated?
(a) Concentrated load
(b) Consumer location
(c) Distributors
(d) Generating stations
(e) None of the above
Which of the following equipment should be
installed by the consumers having low power
factor?
(a) Synchronous condensers
(b) Capacitor bank
(c) Tap changing transformer
(d) Any of the above
(e) None of the above
Which of the following equipment is used to limit short-circuit current level in a substation?

(a) Isolator
(b) Lightning switch
(c) Coupling capacitor
(d) Series reactor

Steepness of the travelling waves is alternated
by ………. of the line
(a) capacitance
(b) inductance
(c) resistance
(d) all of the above
The limit of distance of transmission line may
be increased by the use of
(a) series resistances
(b) shunt capacitors and series reactors
(c) series capacitors and shunt reactors
(d) synchronous condensers
(e) none of the above
By which of the following feactors is the sag
of a transmission line least affected?
(a) Current through the conductor
(b) Ice deposited on the conductor
(c) Self weight of conductor
(d) Temperature of surrounding air
(e) None of the above
Which of the following cause transient
disturbances?
(a) Faults
(b) Load variations
(c) Switching operations
(d) Any of the above
A gay wire
(a) protects conductors against shortcircuiting
(b) provides emergency earth route
(c) provides protection against surges
(d) supports the pole
Which of the following is neglected in the
analysis of short transmission lines?
(a) Series impedance
(b) Shunt admittance
(c) I2R loss
(d) None of the above
(e) All of the above
Basically the boosters are
(a) synchronous motors
(b) capacitors
(c) inductors
(d) transformers
Which of the following is a static exciter?
(a) Rectifier
(b) Rotorol
(c) Amplidyne
(d) D.C. separately excited generator
For exact compensation of voltage drop in the
feeder the booster
(a) must be earthed
(b) must work on line voltage
(c) must work on linear portion of its
V-I characteristics
(d) must work on non-linear portion of its
V-I characteristics
The purpose of using a booster is to
(a) increase current
(b) reduce current
(c) reduce voltage drop
(d) compensate for voltage drop
(e) none of the above
Induction regulators are used for voltage
control in
(a) alternators
(b) primary distribution
(c) secondary distribution
(d) none of the above
A synchronous condenser is generally installed
at the …….. of the transmission line
(a) receiving end
(b) sending end
(c) middle
(d) none of the above
The area of cross-section of the neutral in a
3-wire D.C. system is generally …….. the area
of cross-section of main conductor
(a) same as
(b) one-fourth
(c) one half
(d) double
For which of the following, the excitation
control method is satisfactory?
(a) Low voltage lines
(b) High voltage lines
(c) Short lines
(d) Long lines
In which of the following cases shunt
capacitance is negligible?
(a) Short transmission lines
(b) Medium transmission lines
(c) Long transmission lines
(d) All transmission lines
A lightning arrester is usually located nearer
to
(a) transformer
(b) isolator
(c) busbar
(d) circuit breaker
(e) none of the above
The material used for the manufacture of
grounding wires is
(a) cast iron
(b) aluminium

Surge absorbers protect against ……….
oscillations
(a) high voltage high frequency
(b) high voltage low frequency
(c) low voltage high frequency
(d) low voltage low frequency
Skin effect is noticeable only at ………
frequencies
(a) audio
(b) low
(c) high
(d) all
Per system stability is least affected by
(a) reactance of generator
(b) input torque
(c) losses
(d) reactance of transmission line
When the load at the receiving end of a long
transmission line is removed, the sending end
voltage is less than the receiving end voltage.
This effect is known as
(a) Ferranti effect
(b) Proximity effect
(c) Kelvin effect
(d) Faraday effect
(e) Skin effect
In medium transmission lines the shunt
capacitance is taken into account in
(a) T-method
(b) π-method
(c) steinmetz method
(d) all of the above
System grounding is done so that
(a) inductive interference between power and
communication circuits can be controlled
(b) the floating potential on the lower voltage
winding for a transformer is brought down
to an insignificant value
(c) the arcing faults to earth would not set up
dangerously high voltage on healthy phases
(d) for all above reasons
Which of the following can be used for
bus-bars?
(a) Tubes
(b) Rods
(c) Bars
(d) Any of the above
If the height of transmission tower is increased,
which of the following parameters is likely to
change?
(a) Capacitance
(b) Inductance
(c) Resistance
(d) All of the above
(e) None of the above
A.C.S.R. conductor having 7 steel stands
surrounded by 25 aluminium conductors will
be specified as
(a) 25/7
(b) 50/15
(c) 7/25
(d) 15/50
Impedance relay is used on ……. transmission
lines
(a) short
(b) medium
(c) long
(d) all
Corona is likely to occur maximum in
(a) transmission lines
(b) distribution lines
(c) domestic wiring
(d) all of the above
The effect of wind pressure is more
predominant on
(a) supporting towers
(b) neutral wires
(c) transmission lines
(d) insulators
As compared to cables, the disadvantages of
transmission lines is
(a) inductive interference between power and
communication circuits
(b) exposure to lightning
(c) exposure to atmospheric hazards like
smoke, ice, etc.
(d) all of the above
In overhead transmission lines the effect of
capacitance cand be neglected when the length
of line is less than
(a) 80 km
(b) 110km
(c) 150 km
(d) 210 km
The effective resistance of a conductor will be
the same as ‘ohmic resistance’ when
(a) power factor is unity
(b) current is uniformly distributed in the
conductor cross-section
(c) voltage is low
(d) current is in true sine wave from
Conductors for high voltage transmission lines
are suspended from towers to
(a) increase clearance from ground
(b) reduce clearance from ground
(c) take care of extension in length during
summer
(d) reduce wind and snow loads

To increase the capacity of a transmission line
for transmitting power which of the following
must be decreased?
(a) Capacitance
(b) Line inductance
(c) Voltage
(d) All of the above
By using bundled conductors which of the
following is reduced?
(a) Power loss due to corona
(b) Capacitance of the circuit
(c) Inductance of the circuit
(d) None of the above
(e) All of the above
Which of the following short-circuits is most
dangerous?
(a) Dead short-circuit
(b) Line to ground short-circuit
(c) Line to line short-circuit
(d) Line to line and ground short-circuit
(e) all of the above
Due to which of the following reasons
aluminium is being favoured as busbar
material?
(a) Low density
(b) Low cost
(c) Ease of fabrication
(d) None of the above
In case of transmission line conductors with
the increase in atmospheric temperature
(a) length decreases but stress increases
(b) length increases but stress decreases
(c) both the length and stress increases
(d) both the length and stress decrease
Skin effect exists only in
(a) a.c. transmission
(b) high voltage d.c. overhead transmission
(c) low voltage d.c. overhead transmission
(d) cables carrying d.c. current
Floating neutral, in 3-phase supply, is
undesirable because it causes
(a) low voltage across the load
(b) high voltage across the load
(c) unequal line voltages across the load
(d) none of the above
The surge resistance of cables is
(a) 20 ohms
(b) 50 ohms
(c) 200 ohms
(d) 300 ohms
The electrostatic stress in underground cables
is
(a) zero at the conductor as well as on the
sheath
(b) same at the conductor and sheath
(c) minimum at the conductor and minimum
at the sheath
(d) maximum at the conductor and minimum
at the sheath
The ground ring transmission lines are used to
(a) reduce the transmission losses
(b) reduce the earth capacitance of the lowest
unit
(c) increase the earth capacitance of the lowest
unit
(d) none of the above
The string efficiency of an insulator can be
increased by
(a) correct grading of insulators of various
capacitances
(b) reducing the number of strings
(c) increasing the number of strings in the
insulator
(d) none of the above
High voltages for transmitting power is
economically available from
(a) d.c. currents
(b) a.c. currents
(c) carrier currents
(d) none of the above
High voltage is primarily used, for long
distance power transmission, to
(a) reduce the time of transmission
(b) reduce the transmission losses
(c) make the system reliable
(d) none of the above
By using bundle conductors, the critical
voltage for the formation of corona will
(a) remain same
(b) decrease
(c) increase
(d) not occur
If the voltage is increased x times, the size of
the conductor would be
(a) reduced to 1/x2 times
(b) reduced to 1/x times
(c) increased x times
(d) increased to x2 times
(e) none of the above
The colour of the neutral of three-core flexible
cable is
(a) blue
(b) brown
(c) red
(d) black
In the cablessheaths are used to
(a) prevent the moisture from entering the
cable

(b) provide strength to the cable
(c) provide proper insulation
(d) none of the above

The charging current in the cables
(a) leads the voltage by 180o
(b) leads the voltageby 90o
(c) lags the voltage by 90o
(d) lags the voltage by 180o
Ground wire is used to
(a) avoid overloading
(b) give the support to the tower
(c) give good regulation
(d) connect a circuit conductor or other
device to an earth-plate
Earthing is necessary to give protection against
(a) danger of electric shock
(b) voltage fluctuation
(c) overloading
(d) high temperature of the conductors
Resistance grounding isused for voltage
between
(a) 3.3kV to 11 kV
(b) 11 kV to 33 kV
(c) 33 kV to 66 kV
(d) none of the above
Solid grounding is adopted for voltages below
(a) 100 V
(b) 200 V
(c) 400 V
(d) 660 V
The size of the earth wire is determined by
(a) the atmospheric conditions
(b) the voltage of the service wires
(c) the ampere capacity of the service wires
(d) none of the above
Transmission lines link
(a) generating station to receiving and
station
(b) receiving and station to distribution
transformer
(c) distribution transformer to consumer
premises
(d) service points to consumer premises
(e) none of the above

(b) 2. (d) 3. (a) 4. (c) 5. (b) 6. (d) 7. (a) 8. (d) 9. (d) 10. (d) 11(c) 12. (b) 13. (d) 14. (d) 15. (a) 16. (c) 17. (d) 18. (d) 19. (c) 20. (d) 21.(d) 22. (b) 23. (b) 24. (a) 25. (a) 26. (c) 27. (d) 28. (d) 29. (d) 30. (d) 31(d) 32. (e) 33. (a) 34. (a) 35. (e) 36. (d) 37. (d) 38. (c) 39. (b) 40. (c) 41.(b) 42. (a) 43. (d) 44. (b) 45. (b) 46. (b) 47. (b) 48. (c) 49. (d) 50. (b)51.(b) 52. (a) 53. (c) 54. (c) 55. (c) 56. (d) 57. (c) 58. (b) 59. (a) 60. (a) 61.(b) 62. (c) 63. (b) 64. (a) 65. (c) 66. (d) 67. (d) 68. (d) 69. (d) 70. (b) 71.(c) 72. (c) 73. (d) 74. (a) 75. (b) 76. (c) 77. (d) 78. (d) 79. (b) 80. (b) 81.(d) 82. (d) 83. (d) 84. (b) 85. (b) 86. (a) 87. (d) 88. (c) 89. (c) 90. (a) 91.(d) 92. (b) 93. (a) 94. (b) 95. (d) 96. (b) 97. (b) 98. (d) 99. (d) 100. (a) 101.(a) 102. (c) 103. (c) 104. (c) 105. (b) 106. (b) 107. (b) 108. (c) 109. (c) 110. (b) 111.(a) 112. (a) 113. (a) 114. (b) 115. (b) 116. (a) 117. (a) 118. (b) 119. (d) 120. (d) 121.(d) 122. (d) 123. (a) 124. (c) 125. (a) 126. (a) 127. (a) 128. (c) 129. (a) 130. (d) 131.(b) 132. (b) 133. (a) 134. (b) 135. (b) 136. (d) 137. (c) 138. (a) 139. (b) 140. (c) 141.(d) 142. (b) 143. (d) 144. (c) 145. (c) 146. (a) 147. (d) 148. (d) 149. (b) 150. (d) 151.(a) 152. (c) 153. (d) 154. (b) 155. (a) 156. (c) 157. (c) 158. (a) 159. (a) 160. (d) 161.(c) 162. (c) 163. (c) 164. (a) 165. (d) 166. (d) 167. (d) 168. (a) 169. (a) 170. (b) 171.(a) 172. (a) 173. (d) 174. (a) 175. (b) 176. (a) 177. (b) 178. (a) 179. (a) 180. (b) 181.(b) 182. (a) 183. (c) 184. (b) 185. (d) 186. (b) 187. (a) 188. (b) 189. (b) 190. (c) 191.(a) 192. (a) 193. (a) 194. (b) 195. (d) 196. (a) 197. (a) 198. (d) 199. (c) 200. (a)

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