Question 1:
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
Answer: _________
Question 2:
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
Answer: _________
Question 3:
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
Answer: _________
Question 4:
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
Answer: _________
Question 5:
Overhead system can be designed for operation up to
A.
11 kV
B.
33 kV
C.
66 kV
D.
400 kV
Answer: _________
Question 6:
Pin type insulators are generally not used for voltages beyond
A.
1 kV
B.
11 kV
C.
22 kV
D.
33 kV
Answer: _________
Question 7:
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
Answer: _________
Question 8:
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
Answer: _________
Question 9:
Distribution lines in India generally use
A.
Wooden poles
B.
R.C.C. poles
C.
Steel towers
D.
None of the above
Answer: _________
Question 10:
A 3-phase 4-wire system is commonly used on
A.
Primary transmission
B.
Secondary transmission
C.
Primary distribution
D.
Secondary distribution
Answer: _________
Question 11:
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.
All of the above
Answer: _________
Question 12:
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
Answer: _________
Question 13:
Multi-core cables generally use
A.
Square conductors
B.
Circular conductors
C.
Rectangular conductors
D.
None of the above
Answer: _________
Question 14:
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
Answer: _________
Question 15:
Transmission voltage of ll kV is normally used for distances upto
A.
20 - 25 km
B.
40 - 50 km
C.
60 - 70 km
D.
80 - 100 km
Answer: _________
Question 16:
The phenomenon of rise in voltage at the receiving end of the open-circuited or lightly loaded line is called the
A.
See-back effect
B.
Ferranti effect
C.
Raman effect
D.
None of the above
Answer: _________
Question 17:
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
Answer: _________
Question 18:
The voltage of the single phase supply to residential consumers is
A.
110 V
B.
210 V
C.
230 V
D.
400 V
Answer: _________
Question 19:
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
Answer: _________
Question 20:
The conductors of the overhead lines are
A.
solid
B.
stranded
C.
both solid and stranded
D.
none of the above
Answer: _________
Question 21:
Which of the following materials is not used for transmission and distribution of electrical power?
A.
Copper
B.
Aluminium
C.
Steel
D.
Tungsten
Answer: _________
Question 22:
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
Answer: _________
Question 23:
The steel used in steel cored conductors is usually
A.
Alloy steel
B.
Stainless steel
C.
Mild steel
D.
High speed steel
Answer: _________
Question 24:
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
Answer: _________
Question 25:
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
Answer: _________
Question 26:
Which of the following is not a constituent for making porcelain insulators?
A.
Quartz
B.
Kaolin
C.
Felspar
D.
Silica
Answer: _________
Question 27:
In transmission lines the cross-arms are made of
A.
Copper
B.
Wood
C.
R.C.C.
D.
Steel
Answer: _________
Question 28:
The underground system cannot be operated above
A.
440 V
B.
11 V
C.
33 V
D.
66 V
Answer: _________
Question 29:
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
Answer: _________
Question 30:
Which of the following D.C. distribution system is the simplest and lowest in first cost?
A.
Radial system
B.
Ring system
C.
Interconnected system
D.
None of the above
Answer: _________
Question 31:
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
Answer: _________
Question 32:
Which of the following distribution systems is more reliable?
A.
Radial system
B.
Tree system
C.
Ring main system
D.
All are equally reliable
Answer: _________
Question 33:
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: _________
Question 34:
There is a greater possibility of occurrence of corona during
A.
Dry weather
B.
Winter
C.
Summer heat
D.
Humid weather
Answer: _________
Question 35:
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
Answer: _________
Question 36:
The material commonly used for sheaths of underground cables is
A.
Lead
B.
Rubber
C.
Copper
D.
Iron
Answer: _________
Question 37:
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
Answer: _________
Question 38:
The voltage drop, for constant voltage transmission is compensated by installing
A.
Inductors
B.
Capacitors
C.
Synchronous motors
D.
All of above
Answer: _________
Question 39:
The operating voltage of extra high tension cables is upto
A.
6.6 kV
B.
11 kV
C.
33 kV
D.
66 kV
Answer: _________
Question 40:
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
Answer: _________
Question 41:
For aluminium, as compared to copper, all the following factors have higher values except
A.
Specific volume
B.
Electrical conductivity
C.
Coefficient of linear expansion
D.
Resistance per unit length for same cross-section
Answer: _________
Question 42:
310 km line is considered as
A.
A long line
B.
A medium line
C.
A short line
D.
Any of the above
Answer: _________
Question 43:
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
Answer: _________
Question 44:
Galvanized steel wire is generally used as
A.
Stay wire
B.
Earth wire
C.
Structural components
D.
All of the above
Answer: _________
Question 45:
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
Answer: _________
Question 46:
The usual spans with R.C.C. poles are
A.
40-50 meters
B.
60-100 meters
C.
80-100 meters
D.
300-500 meters
Answer: _________
Question 47:
The power factor of industrial loads is generally
A.
Unity
B.
Lagging
C.
Leading
D.
Zero
Answer: _________
Question 48:
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
Answer: _________
Question 49:
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
Answer: _________
Question 50:
When a live conductor of public electric supply 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
Answer: _________
Question 51:
Which of the following regulations is considered best?
A.
50 %
B.
20 %
C.
10 %
D.
2 %
Answer: _________
Question 52:
Overhead lines generally use
A.
Copper conductors
B.
All aluminium conductors
C.
A.C.S.R. conductors
D.
None of these
Answer: _________
Question 53:
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
Answer: _________
Question 54:
Low voltage cables are meant for use up to
A.
1.1 kV
B.
3.3 kV
C.
6.6 kV
D.
11 kV
Answer: _________
Question 55:
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
Answer: _________
Question 56:
Aluminium has a specific gravity of
A.
1.5
B.
2.7
C.
4.2
D.
7.8
Answer: _________
Question 57:
In AC.S.R. Conductors, the insulation between aluminium and steel conductors is
A.
Insulin
B.
Bitumen
C.
Varnish
D.
No insulation is required
Answer: _________
Question 58:
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
Answer: _________
Question 59:
The current drawn by the line due to corona losses is
A.
Non-sinusoidal
B.
Sinusoidal
C.
Triangular
D.
Square
Answer: _________
Question 60:
are the conductors, which connect the consumer's terminals to the distribution
A.
Distributors
B.
Service mains
C.
Feeders
D.
None of the above
Answer: _________
Question 61:
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
Answer: _________
Question 62:
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
Answer: _________
Question 63:
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
Answer: _________
Question 64:
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 reactants
D.
Improvement of power factor at times of moderate and heavy loads
Answer: _________
Question 65:
Electromechanical voltage regulators are generally used in
A.
Reactors
B.
Generators
C.
Transformers
D.
All of the above
Answer: _________
Question 66:
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
Answer: _________
Question 67:
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
Answer: _________
Question 68:
A conductor, due to sag between two supports, takes the form of
A.
Semicircle
B.
Triangle
C.
Ellipse
D.
Catenary
Answer: _________
Question 69:
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 buried in the earth
C.
mechanical damage
D.
all of the above
Answer: _________
Question 70:
The operating voltage of super-tension cables is up to
A.
3.3 kV
B.
6.6 kV
C.
11 kV
D.
33 kV
Answer: _________
Question 71:
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: _________
Question 72:
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
Answer: _________
Question 73:
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
Answer: _________
Question 74:
Large industrial consumers are supplied electrical energy at
A.
400 V
B.
11 kV
C.
66 kV
D.
400 kV
Answer: _________
Question 75:
In a substation the following equipment is not installed
A.
Exciters
B.
Series capacitors
C.
Shunt reactors
D.
Voltaire transformers
Answer: _________
Question 76:
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: _________
Question 77:
The material commonly used for insulation in high voltage cables is
A.
Lead
B.
Paper
C.
Rubber
D.
None of the above
Answer: _________
Question 78:
The material generally used for armour of high voltage cables is
A.
Aluminium
B.
Steel
C.
Brass
D.
Copper
Answer: _________
Question 79:
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 half scheme
D.
Main and transfer scheme
Answer: _________
Question 80:
Corona 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 value)/cm
Answer: _________
Question 81:
Which of the following are the constants of the transmission lines?
A.
Resistance
B.
Inductance
C.
Capacitance
D.
All of the above
Answer: _________
Question 82:
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
Answer: _________
Question 83:
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
Answer: _________
Question 84:
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
Answer: _________
Question 85:
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
Answer: _________
Question 86:
A booster is a
A.
Series wound generator
B.
Shunt wound generator
C.
Synchronous generator
D.
None of the above
Answer: _________
Question 87:
The effect of corona can be detected by
A.
Presence of ozone detected by odour
B.
Hissing sound
C.
Faint luminous glow of bluish color
D.
All of the above
Answer: _________
Question 88:
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
Answer: _________
Question 89:
High voltage transmission lines use
A.
Suspension insulators
B.
Pin insulators
C.
Both (A) and (B)
D.
None of the above
Answer: _________
Question 90:
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 reactants
D.
Improvement of power factor at times of moderate and heavy loads
Answer: _________
Question 91:
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
Answer: _________
Question 92:
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
Answer: _________
Question 93:
A feeder, in a transmission system, feeds power to
A.
Distributors
B.
Generating stations
C.
Service mains
D.
All of the above
Answer: _________
Question 94:
Transmission line insulators are made of
A.
glass
B.
porcelain
C.
iron
D.
P.V.C.
Answer: _________
Question 95:
Skin effect is proportional to
A.
$${left( {{ ext{conductor diameter}}}
ight)^{frac{1}{2}}}$$
B.
(conductor diameter) 4
C.
(conductor diameter) 2
D.
(conductor diameter) 3
Answer: _________
Question 96:
The operating voltage of high voltage cables is up to
A.
l.lkV
B.
3.3kV
C.
6.6kV
D.
llkV
Answer: _________
Question 97:
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
Answer: _________
Question 98:
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.
All of the above
Answer: _________
Question 99:
Which of the following is the source of heat generation in the cables?
A.
Dielectric losses in cable insulation
B.
losses in the conductor
C.
Losses in the metallic sheathings and armourings
D.
All of the above
Answer: _________
Question 100:
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
Answer: _________
Question 101:
________ are the conductors, which connect the consumer's terminals to the distribution.
A.
Distributors
B.
Service mains
C.
Feeders
D.
None of the above
Answer: _________
Question 102:
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
Answer: _________
Question 103:
The wooden poles well impregnated with creosote oil or any preservative compound has life
A.
From 2 to 5 years
B.
10 to 15 years
C.
25 to 30 years
D.
60 to 70 years
Answer: _________
Question 104:
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: _________
Question 105:
The loads on distributors systems are generally
A.
Balanced
B.
Unbalanced
C.
Either of the above
D.
None of the above
Answer: _________
Answer Key
1:
D
Solution: A bus-bar is rated based on current, voltage, frequency, and short time current . Current: The maximum amount of current the bus-bar can carry without overheating. Voltage: The highest voltage the bus-bar can handle safely without breakdown. Frequency: The frequency of the alternating current (AC) the bus-bar can operate with. Short time current: The maximum short-circuit current the bus-bar can withstand for a brief period without damage. These ratings ensure the bus-bar operates safely and efficiently within its designed parameters.
2:
D
3:
C
4:
D
5:
D
6:
D
7:
B
8:
C
9:
B
10:
D
11:
D
12:
C
13:
D
Solution: The correct answer is B: Circular conductors Here's why: Multi-core cables contain multiple insulated conductors within a single outer sheath. Shape of Conductors : The shape of each individual conductor plays a vital role in the cable’s flexibility and efficiency. Circular Conductors : Generally chosen for multi-core cables because: Flexibility : Circular conductors allow the cable to be bent and flexed more easily without damaging the insulation or conductors. This is essential for applications where the cable needs to be routed around corners or through tight spaces. Ease of Manufacturing : It's easier and more cost-effective to manufacture circular conductors compared to square or rectangular ones. Better Insulation : Circular conductors allow for more uniform insulation around the conductor, reducing the risk of electrical breakdown. Square or Rectangular Conductors : While these shapes might offer slightly better space utilization in some applications, their sharp edges can create stress points in the insulation, leading to premature failure, and they are much less flexible. So, for practicality, ease of manufacturing, flexibility, and insulation reliability, circular conductors are the standard choice in multi-core cables.
14:
D
15:
A
16:
B
17:
B
18:
C
19:
C
20:
B
Solution: The correct answer is Option B: stranded Here's why: Solid conductors are generally too rigid and inflexible for overhead lines. They would be prone to breaking due to vibrations, wind, and temperature changes. Stranded conductors are made up of multiple wires twisted together. This construction provides flexibility, making them less susceptible to damage from external forces. The flexibility also makes them easier to handle and install. Therefore, overhead lines use stranded conductors for better durability and ease of use.
21:
D
22:
A
23:
C
24:
D
25:
B
Solution: The angular displacement between two interconnected stations refers to the phase angle difference between their terminal voltages. While armature reactance and synchronous reactance of alternators do contribute to this displacement , their effects are relatively small compared to the impact of the interconnecting transmission line. The primary cause is the reactance of the interconnector . This reactance causes a voltage drop proportional to the power transmitted, which directly changes the phase angle between the two stations. The higher the interconnector's reactance , the greater the angular displacement for the same amount of transmitted power. Therefore, the main reason is the reactance of the interconnector , making Option B correct.
26:
D
27:
D
28:
D
29:
A
30:
A
31:
C
32:
C
33:
B
34:
D
35:
D
36:
A
37:
B
38:
C
39:
D
40:
C
41:
B
42:
A
43:
C
Solution: Tap changing transformers are used to regulate the output voltage by changing the turn ratio. Tappings are typically provided on the high voltage winding rather than the low voltage side. This is because the current in the high voltage winding is lower , making it easier and safer to implement tap changes without handling large currents. Changing taps on the high voltage side also reduces the size and cost of the tap-changing equipment. Option A and Option B are incorrect because although technically possible, it is not common practice to place tappings on the primary or secondary specifically unless they are also the high voltage side. Option D is incorrect because while taps can theoretically be placed on any winding, they are practically and most commonly placed on the high voltage winding . Therefore, Option C: High voltage winding is the correct answer.
44:
D
45:
A
46:
C
47:
B
48:
C
49:
B
50:
A
51:
D
Solution: Voltage regulation in transmission and distribution systems refers to the change in voltage from no-load to full-load conditions. It's usually expressed as a percentage. A lower percentage voltage regulation means there's less voltage drop from no load to full load. This is desirable because it ensures that the voltage at the customer's end remains relatively constant, regardless of the load. Consistent voltage is important for the proper functioning of electrical equipment. Therefore, a lower voltage regulation is considered better. Out of the given options, 2% represents the smallest change in voltage and is thus the best.
52:
C
53:
C
54:
A
55:
B
56:
B
57:
D
58:
A
Solution: This question asks about the voltage drop at the middle of a uniformly loaded DC distributor when it's fed from both ends compared to when it's fed from one end only . Let's break it down: Imagine a wire supplying power to multiple loads evenly spread along its length. One-End Fed: If the power comes from just one end, the farthest point (the other end) will have the lowest voltage. The voltage drop increases as you move away from the feeding point. The maximum voltage drop occurs at the far end , and the voltage drop at the midpoint will be significant. Both-Ends Fed: Now, imagine feeding the same wire from both ends with the same voltage. Each end supplies power to half of the loads. The point with the lowest voltage will now be the middle point, because it is the farthest point from each supply end. However, the voltage drop to the middle point will be much smaller because it's only fed with half of the total current. Here's the key idea for the mathematically inclined: For a distributor fed at one end, the voltage drop is proportional to the square of the distance. For a distributor fed at both ends, with uniform loading, the maximum voltage drop (at the midpoint) is one-fourth of what it would be if it were fed from only one end. Therefore, the correct answer is Option A: One-fourth
59:
A
60:
B
61:
B
62:
C
63:
A
64:
A
65:
B
66:
B
67:
C
Solution: Option A: 1-phase 3-wire This represents a single-phase electrical system with three wires. It is commonly used for residential and small commercial applications where a split-phase system is required, providing two live conductors and one neutral conductor. Option B: 1-phase 4-wire This is another single-phase system, but it includes an additional ground wire (4 wires in total). It is commonly used for applications where a ground connection is necessary for safety, such as in residential distribution panels. Option C: 3-phase 3-wire This represents a three-phase electrical system with three wires and no neutral conductor. It is used in some industrial and commercial applications where a neutral conductor is not required, and balanced loads are expected across the three phases. Option D: 3-phase 4-wire This is a standard three-phase electrical system with four wires, including three live conductors and one neutral conductor. It is widely used for industrial and commercial applications, providing a neutral for unbalanced loads and additional safety. The option that is not generally used in standard electrical distribution systems is Option C: 3-phase 3-wire . While this configuration may be used in some specific industrial applications, it is less common in comparison to the other options provided. Most three-phase systems include a neutral conductor (Option D) for flexibility and safety. Therefore, Option C: 3-phase 3-wire is the system that is not generally used in common electrical distribution.
68:
D
69:
D
70:
D
71:
C
72:
A
73:
B
74:
C
75:
A
Solution: Definition: A substation is a part of the power system used to transform voltage levels, control power flow, and provide protection and switching operations. Equipment in substations: Common equipment includes series capacitors for voltage support, shunt reactors for reactive power control, and voltage transformers for measurement and protection purposes. About exciters: Exciters are devices used to supply DC field current to the rotor winding of synchronous machines such as generators or motors. They are installed in power plants or generator systems, not in substations. Reason: Since substations do not contain generating units, there is no need for exciters, making them absent from substation installations. Conclusion: Among the given options, exciters are not installed in substations.
76:
C
77:
B
78:
B
79:
B
80:
D
81:
D
82:
D
83:
B
84:
D
85:
C
86:
A
87:
D
88:
C
89:
A
90:
A
91:
D
92:
D
93:
A
94:
B
95:
C
96:
D
97:
A
98:
D
99:
D
100:
D
101:
B
102:
A
103:
C
104:
C
Solution: Corona losses are minimum : This is not the correct answer. While minimizing corona losses is important for efficient power transmission, it doesn't directly determine the maximum power transmission. Maximum power transmission is influenced by factors such as sending and receiving end voltages. Reactance is high : This is not the correct answer. High reactance can lead to increased voltage drop and reduced power transfer efficiency. Sending end voltage is more : This is the correct answer. The power transmitted in a transmission line is given by the formula ( P = frac{V_s^2}{Z} ), where ( P ) is power, ( V_s ) is sending end voltage, and ( Z ) is the total impedance of the line. Therefore, increasing the sending end voltage increases the power transmitted. Receiving end voltage is more : This is not the correct answer. While receiving end voltage is important, the question specifically asks about maximizing power transmission, which is influenced by the sending end voltage. Therefore, in the context of the question, the power transmitted will be maximum when the Sending end voltage is more (Option C).
105:
B