Deck 4: Electrical Transmission and Insulation

Question 1

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

Answer 1

any of the above

Question 2

The current drawn by the line due to corona losses is

A)non-sinusoidal
B)sinusoidal
C)triangular
D)square

Answer 2

non-sinusoidal

Question 3

Pin type insulators are generally not used for voltages beyond

A)1 kV
B)11 kV
C)22 kV
D)33 kV

Answer 3

33 kV

Question 4

Aluminium has a specific gravity of

A)1.5
B)2.7
C)4.2
D)7.8

Question 5

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

Question 6

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 cross-section

Question 7

Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ?

A)Static condenser
B)Synchronous condenser
C)Tap changing transformer
D)Booster transformer

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

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

Question 13

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)Medium as well as long transmission lines

Question 14

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

Question 15

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

Question 16

When an alternator connected to the bus-bar is shut down the bus-bar voltage will

A)fall
B)rise
C)remain unchanged
D)none of the above

Question 17

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

Question 18

Electro-mechanical voltage regulators are generally used in

A)reactors
B)generators
C)transformers
D)all of the above

Question 19

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

Question 20

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

Question 21

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

Question 22

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

Question 23

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