Deck 3: Transmission System and Equipment

Question 1

A feeder, in a transmission system, feeds power to

A)distributors
B)generating stations
C)service mains
D)all of the above

Answer 1

distributors

Question 2

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

Answer 2

sending end voltage is more

Question 3

A 3-phase 4 wire system is commonly used on

A)primary transmission
B)secondary transmission
C)primary distribution
D)secondary distribution

Answer 3

secondary distribution

Question 4

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

Question 5

Which of the following is not a constituent for making porcelain insulators ?

A)Quartz
B)Kaolin
C)Felspar
D)Silica

Question 6

There is a greater possibility of occurence of corona during

A)dry weather
B)winter
C)summer heat
D)humid weather

Question 7

Which of the following relays is used on long transmission lines ?

A)Impedance relay
B)Mho's relay
C)Reactance relay
D)None of the above

Question 8

The steel used in steel cored conductors is usually

A)alloy steel
B)stainless steel
C)mild steel
D)high speed steel

Question 9

Which of the following distribution systems is more reliable ?

A)Radial system
B)Tree system
C)Ring main system
D)All are equally reliable

Question 10

Which of the following characteristics should the line supports for transmission lines possess ?

A)Low cost
B)High mechanical strength
C)Longer life
D)All of the above

Question 11

Transmission voltage of llkV is normally used for distances upto

A)20-25 km
B)40-50 km
C)60-70 km
D)80-100 km

Question 12

Which of the following regulations is considered best?

A)50%
B)20%
C)10%
D)2%

Question 13

Skin effect is proportional to

A)(conductor diameter)
B)(conductor diameter).
C)(conductor diameter),
D)(conductor diameter)..

Question 14

A conductor, due to sag between two supports, takes the form of

A)semi-circle
B)triangle
C)ellipse
D)catenary

Question 15

In AC.S.R. conductors, the insulation between aluminium and steel conductors is

A)insulin
B)bitumen
C)varnish
D)no insulation is required

Question 16

Which of the followingbus-bar schemes has the lowest cost ?

A)Ring bus-bar scheme
B)Single bus-bar scheme
C)Breaker and a half scheme
D)Main and transfer scheme

Question 17

Owing to skin effect

A)current flows through the half cross-section 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)any of the above

Question 18

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

Question 19

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

Question 20

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

Question 21

A circuit is disconnected by isolators when

A)line is energized
B)there is no current in the line
C)line is on full load
D)circuit breaker is not open

Question 22

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

Question 23

In a substation the following equipment is not installed

A)exciters
B)series capacitors
C)shunt reactors
D)voltatre transformers

Question 24

jCorona usually 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 v^lue)/cm

Question 25

The voltage drop, for constant voltage transmission is compensated by installing

A)inductors
B)capacitors
C)synchronous motors
D)all of above