Deck 2: Electrical Supply and Distribution

Question 1

Most of the high voltage transmission lines in India are

A)underground
B)overhead
C)either of the above
D)none of the above

Answer 1

overhead

Question 2

The distributors for residential areas are

A)single phase
B)three-phase three wire
C)three-phase four wire
D)none of the above

Answer 2

three-phase four wire

Question 3

The conductors of the overhead lines are

A)solid
B)stranded
C)both solid and stranded
D)none of the above

Answer 3

stranded

Question 4

High voltage transmission lines use

A)suspension insulators
B)pin insulators
C)both (a) and (b)
D)none of the above

Question 5

Distribution lines in India generally use

A)wooden poles
B)R.C.C. poles
C)steel towers
D)none of the above

Question 6

The material commonly used for insulation in high voltage cables is

A)lead
B)paper
C)rubber
D)none of the above

Question 7

The loads on distributors systems are generally

A)balanced
B)unbalanced
C)either of the above
D)none of the above

Question 8

The power factor of industrial loads is generally

A)unity
B)lagging
C)leading
D)zero

Question 9

Overhead lines generally use

A)copper conductors
B)all aluminium conductors
C)A.C.S.R. conductors
D)none of these

Question 10

In transmission lines the cross-arms are made of

A)copper
B)wood
C)R.C.C.
D)steel

Question 11

The material generally used for armour of high voltage cables is

A)aluminium
B)steel
C)brass
D)copper

Question 12

Transmission line insulators are made of

A)glass
B)porcelain
C)iron
D)P.V.C.

Question 13

The material commonly used for sheaths of underground cables is

A)lead
B)rubber
C)copper
D)iron

Question 14

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

Question 15

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

Question 16

Large industrial consumers are supplied electrical energy at

A)400 V
B)11 kV
C)66 kV
D)400 kV

Question 17

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 machine^ run as unloaded motors
D)equalize voltages on the positive and negative outers

Question 18

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

Question 19

Transmitted power remaining the same, if supply voltage 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

Question 20

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 the middle point is

A)one-fourth
B)one-third
C)one-half
D)twice

Question 21

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

Question 22

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

Question 23

For an overhead line, the surge impedance is taken as

A)20-30 ohms
B)70-80 ohms
C)100-200 ohms
D)500-1000 ohms

Question 24

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