Question 1

A feeder, in a transmission system, feeds power to
A)distributors
B)generating stations
C)service mains
D)all of the above

Accepted Answer

Feeders are responsible for carrying power from substations to distributors, which then distribute the power to consumers.

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

Accepted Answer

The power transmitted will be maximum when the sending end voltage is more. This is because the power transmitted is given by the equation P = VI, where P is the power, V is the voltage, and I is the current. Therefore, if the voltage is increased, the power transmitted will also increase.

Question 3

A 3-phase 4 wire system is commonly used on
A)primary transmission
B)secondary transmission
C)primary distribution
D)secondary distribution

Accepted Answer

A 3-phase 4 wire system is typically used in secondary distribution to provide both three-phase and single-phase supplies to consumers.

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

Accepted Answer

Overhead transmission lines require materials with high strength, low weight, and good electrical conductivity. Steel cored aluminium, galvanised steel, and cadmium copper all meet these requirements.

Question 5

Which of the following is not a constituent for making porcelain insulators ?
A)Quartz
B)Kaolin
C)Felspar
D)Silica

Accepted Answer

Silica is not typically used as a primary constituent in porcelain insulators; instead, quartz, kaolin, and felspar are the main materials used.

Question 6

There is a greater possibility of occurence of corona during
A)dry weather
B)winter
C)summer heat
D)humid weather

Accepted Answer

Corona discharge is more likely to occur in humid weather because moisture in the air increases the conductivity of the air, facilitating the ionization process that leads to corona discharge.

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

Accepted Answer

Mho's relay is specifically designed for long transmission lines because it has a characteristic that is inherently directional and compensates for the line length, making it suitable for varying impedance conditions typical in long transmission lines.

Question 8

The steel used in steel cored conductors is usually
A)alloy steel
B)stainless steel
C)mild steel
D)high speed steel

Accepted Answer

Mild steel is typically used in steel-cored conductors due to its good tensile strength and relatively low cost, making it suitable for reinforcing the conductor without significantly increasing its weight or cost.

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

Accepted Answer

The ring main system is more reliable because it provides multiple paths for power to flow. If one segment of the system fails, power can be rerouted through another path, minimizing downtime and enhancing reliability compared to radial and tree systems, which do not offer such redundancy.

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

Accepted Answer

Line supports for transmission lines should possess all these characteristics to ensure cost-effectiveness, durability, and reliability.

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

Accepted Answer

Transmission voltage of 11kV is typically used for distances up to 20-25 km, as higher voltages are more efficient for longer distances due to reduced energy losses.

Question 12

Which of the following regulations is considered best?
A)50%
B)20%
C)10%
D)2%

Accepted Answer

The question seems to be missing context that would clarify what these percentages refer to. However, in many contexts where lower percentages are considered better (such as error rates, failure rates, or interest rates for loans), 2% would be considered the best option among those listed because it represents the lowest value.

Question 13

Skin effect is proportional to
A)(conductor diameter)
B)(conductor diameter).
C)(conductor diameter),
D)(conductor diameter)..

Accepted Answer

The answer of Skin effect is proportional to
A)(conductor diameter)
B)(conductor diameter).
C)(conductor...

Question 14

A conductor, due to sag between two supports, takes the form of
A)semi-circle
B)triangle
C)ellipse
D)catenary

Accepted Answer

A conductor between two supports, due to sag, takes the form of a catenary. This is because the conductor is subject to uniform gravitational force along its length, leading to a curve that is mathematically described as a 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

Accepted Answer

In AC.S.R. (Aluminum Conductor Steel Reinforced) conductors, no insulation is required between the aluminum and steel conductors because the steel core is used for mechanical strength while the aluminum is used for electrical conductivity, and they are designed to be in direct contact.

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

Accepted Answer

The single bus-bar scheme is the simplest and least expensive of all the bus-bar schemes listed. It consists of a single bus-bar to which all the circuits are connected directly. This simplicity leads to lower costs in comparison to more complex schemes like the ring, breaker and a half, or main and transfer schemes, which require additional equipment and complexity.

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

Accepted Answer

Skin effect causes the electric current to distribute itself within a conductor with the current density being largest near the surface of the conductor and decreasing at greater depths. This means the portion of the conductor near the surface carries more current, and the core of the conductor carries less current.

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

Accepted Answer

String efficiency can be improved by using a guard ring, grading the insulator, or using a long cross arm. Each of these methods helps in distributing the electrical stress more evenly across the insulator string, thereby improving its efficiency.

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

Accepted Answer

The steel core in aluminium conductors is provided to increase the tensile strength. This combination allows the conductor to carry more weight and withstand more physical stress, which is particularly useful in overhead power lines where mechanical strength is crucial.

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

Accepted Answer

Bus-bars are rated based on current, voltage, frequency, and short time current because these parameters determine the capacity and safety of the bus-bar in handling electrical power under both normal and fault conditions.

Quiz 3: Transmission System and Equipment

A feeder, in a transmission system, feeds power to

The power transmitted will be maximum when

A 3-phase 4 wire system is commonly used on

Which of the following materials is used for overhead transmission lines ?

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

There is a greater possibility of occurence of corona during

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

The steel used in steel cored conductors is usually

Which of the following distribution systems is more reliable ?

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

Transmission voltage of llkV is normally used for distances upto

Which of the following regulations is considered best?

Skin effect is proportional to

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

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

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

Owing to skin effect

By which of the following methods string efficiency can be improved ?

In aluminium conductors, steel core is provided to

By which of the following a bus-bar is rated ?