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All questions of Power Systems for Electrical Engineering (EE) Exam
The main consideration for operating transmission line at high voltage is- a)To increase efficiency only
- b)To reduce power loss only
- c)To increase power transmission capability
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
The main consideration for operating transmission line at high voltage is
a)
To increase efficiency only
b)
To reduce power loss only
c)
To increase power transmission capability
d)
All of the above
 | Sanskriti Bajaj answered |
The main considerations for operating transmission line at high voltage are:
1) To increase efficiency only
2) To reduce power loss only
3) To increase power transmission capability
An ac current passing through a conductor distributes _________ throughout the cross section and is frequency_________- a)Non uniformly and independent
- b)Non uniformly and dependent
- c)Uniformly and independent
- d)Uniformly and dependent
Correct answer is option 'B'. Can you explain this answer?
An ac current passing through a conductor distributes _________ throughout the cross section and is frequency_________
a)
Non uniformly and independent
b)
Non uniformly and dependent
c)
Uniformly and independent
d)
Uniformly and dependent
 | Lavanya Menon answered |
Skin effect is the tendency of a high-frequency alternating current to flow through only the outer layer of a conductor. It is more predominant in AC transmission.
When an AC current is passing through a conductor distributes non-uniformly throughout the conductor. And it is dependent of frequency, it is more in high frequency transmission.
Corona discharge is generally ________ in colour:- a)Blackish
- b)Bluish
- c)Yellowish
- d)Brownish
Correct answer is option 'B'. Can you explain this answer?
Corona discharge is generally ________ in colour:
a)
Blackish
b)
Bluish
c)
Yellowish
d)
Brownish
 | Zoya Sharma answered |
The phenomenon of electrical discharge occurring in transmission line for high values of voltage is known as the corona effect. If the voltage across the lines still gets increased the glow becomes more and more intense along with hissing noise, inducing high power loss into the system. This is generally in violet or blue color.
In a circuit breaker, ionisation is not facilitated by:- a)Material of contacts
- b)Increase of mean path
- c)Increase of filed strength
- d)High temperature of surrounding medium
Correct answer is option 'A'. Can you explain this answer?
In a circuit breaker, ionisation is not facilitated by:
a)
Material of contacts
b)
Increase of mean path
c)
Increase of filed strength
d)
High temperature of surrounding medium
 | Neha Nambiar answered |
In a circuit breaker, ionisation is facilitated by
1) Increase of mean free length
2) Increase of filed strength
3) High temperature of surrounding medium
Which of the following used to make bus bars and transmission line conductors?- a)Lead
- b)Aluminium
- c)Nichrome
- d)Cadmium
Correct answer is option 'B'. Can you explain this answer?
Which of the following used to make bus bars and transmission line conductors?
a)
Lead
b)
Aluminium
c)
Nichrome
d)
Cadmium
 | Sharmila Kulkarni answered |
Aluminium is used for a whole range of busbar applications and to make transmission line conductors due to its light weight and durability.
The type of protection that does not respond to faults occurring beyond its zone even though the fault current may pass through the zone is- a)Unit protection
- b)Generator protection
- c)Back – up protection
- d)Busbar protection
Correct answer is option 'A'. Can you explain this answer?
The type of protection that does not respond to faults occurring beyond its zone even though the fault current may pass through the zone is
a)
Unit protection
b)
Generator protection
c)
Back – up protection
d)
Busbar protection
 | Anand Mehta answered |
Unit type schemes protect a specific area of the system i.e. a transformer, transmission line, generator or bus bar. The unit protection schemes are based on Kirchhoff’s Current Law (the sum of the currents entering an area of the system must be zero). Any deviation from this must indicate an abnormal current path. In these schemes, the effects of any disturbance or operating condition outside the area of interest are totally ignored and the protection must be designed to be stable above the maximum possible fault current that could flow through the protected area.
A thermal protection switch provides protection against- a)Over load
- b)Under voltage
- c)Short circuit
- d)Over-voltage
Correct answer is option 'A'. Can you explain this answer?
A thermal protection switch provides protection against
a)
Over load
b)
Under voltage
c)
Short circuit
d)
Over-voltage
 | Avik Iyer answered |
A thermal switch is a device which normally opens at a high temperature and re-closes when the temperature drops. The thermal switch may be a bimetallic strip, often encased in a tubular glass bulb to protect it from dust or short circuit.
A thermal switch is usually reusable, and is therefore suited to protecting against temporary situations which are common and user-correctable. Thermal switches are used in power supplies in case of overload, and also as thermostats in some heating and cooling systems.
A pitot relay is used for:- a)High speed tripping
- b)Delayed tripping
- c)Pre-set tripping
- d)No tripping
Correct answer is option 'A'. Can you explain this answer?
A pitot relay is used for:
a)
High speed tripping
b)
Delayed tripping
c)
Pre-set tripping
d)
No tripping
 | Harshad Singh answered |
Pitot relay is to be attached to a pipe that connects a transformer body and a conservator in order to detect any trouble and to protect the transformer from any accident. It has slight failure contacts to detect gas accumulation as well as serious failure contacts to detect rapid flow of insulation liquid. It is sued for high speed tripping.
Isolators are used for disconnecting a circuit when- a)Line is energised
- b)Line is on full load
- c)Line carries no current
- d)Can be operated under any condition
Correct answer is option 'C'. Can you explain this answer?
Isolators are used for disconnecting a circuit when
a)
Line is energised
b)
Line is on full load
c)
Line carries no current
d)
Can be operated under any condition
| | Rahul Chauhan answered |
Isolators are used to open a circuit under no load. Its main purpose is to isolate one portion of the circuit from the other and is not intended to be opened while current is flowing in the line. Isolators are generally used on both ends of the breaker in order that repair or replacement of circuit breaker can be done without and danger.
Reactance relays are generally deployed for the phase faults in1) Short lines2) Medium lines3) Long lines- a)Only 1 and 2
- b)Only 2 and 3
- c)Only 1
- d)None
Correct answer is option 'C'. Can you explain this answer?
Reactance relays are generally deployed for the phase faults in
1) Short lines
2) Medium lines
3) Long lines
a)
Only 1 and 2
b)
Only 2 and 3
c)
Only 1
d)
None
| | Devansh Das answered |
Impedance relay is used for the phase faults in medium transmission line
Reactance relay is used for the phase faults in short transmission line
Mho relay is used for the phase faults in long transmission line
Air Blast Circuit breaker is employed among which of the following?i. Arc furnace dutyii. Traction system- a)Only i
- b)Only ii
- c)i and ii both
- d)Neither (i) nor (ii)
Correct answer is option 'C'. Can you explain this answer?
Air Blast Circuit breaker is employed among which of the following?
i. Arc furnace duty
ii. Traction system
a)
Only i
b)
Only ii
c)
i and ii both
d)
Neither (i) nor (ii)
| | Ashish Chakraborty answered |
Air blast circuit breakers are used in arc furnace duty, traction systems, and used for the railway electrification. Because they are suitable for repeated duty.
In transmission lines, the effective resistance of a conductor is increased by- a)Proximity effect and Skin effect
- b)Corona effect and Proximity effect
- c)Corona effect and Skin effect
- d)Proximity effect only
Correct answer is option 'A'. Can you explain this answer?
In transmission lines, the effective resistance of a conductor is increased by
a)
Proximity effect and Skin effect
b)
Corona effect and Proximity effect
c)
Corona effect and Skin effect
d)
Proximity effect only
 | Hridoy Chakraborty answered |
Skin effect is the tendency of an alternating electric current to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases with greater depths in the conductor.
The electric current flows mainly at the skin of the conductor, between the outer surface and a level called the skin depth. The skin effect causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller, thus reducing the effective cross-section of the conductor.
The alternating flux in a conductor is caused by the current of the other nearby conductor. This flux produces a circulating current or eddy current in the conductor which results an apparent increase in the resistance of the wire. Thus, more power losses in the windings. This phenomenon is called proximity effect.
Phase modifiers in AC transmission line are-- a)Synchronous machines
- b)Induction machines
- c)DC machines
- d)Transformers
Correct answer is option 'A'. Can you explain this answer?
Phase modifiers in AC transmission line are-
a)
Synchronous machines
b)
Induction machines
c)
DC machines
d)
Transformers
 | Naveen Mukherjee answered |
A synchronous motor can be made to take either a lagging or leading current from the line by alternating its excitation. Idle running synchronous motors are sued in connection with power plants to correct for low power factor of the load and thus reduced the current and power losses in the feeders and generators.
Synchronous phase modifier differ from the ordinary synchronous motor is as much as they are built for the highest economical speeds and provided with smaller shafts and bearings.
Earth fault relays are- a)non-directional relays
- b)direction relays
- c)short operate time relays
- d)long operate time relays
Correct answer is option 'A'. Can you explain this answer?
Earth fault relays are
a)
non-directional relays
b)
direction relays
c)
short operate time relays
d)
long operate time relays
 | Shraddha Datta answered |
Earth fault relays are typically **non-directional relays**. These relays are designed to detect faults to ground in electrical systems regardless of the direction of current flow. Therefore, the correct answer is:
1. non-directional relays
The average motor load of a consumer is 250 kW at a power factor 0.85 lag. The consumer is charged electricity at the tariff of Rs.50/kVA of maximum demand plus 10 paise per unit consumed. Determine the consumer’s annual bill for a load factor of 70%- a)Rs. 158005.5
- b)Rs. 163005.5
- c)Rs.153300
- d)Rs.168005.5
Correct answer is option 'D'. Can you explain this answer?
The average motor load of a consumer is 250 kW at a power factor 0.85 lag. The consumer is charged electricity at the tariff of Rs.50/kVA of maximum demand plus 10 paise per unit consumed. Determine the consumer’s annual bill for a load factor of 70%
a)
Rs. 158005.5
b)
Rs. 163005.5
c)
Rs.153300
d)
Rs.168005.5
| | Divya Singh answered |
Consumer motor load = 250 kW
Maximum demand = 250/0.85 = 294.11
Unit consumed per year = maximum demand × load factor × hours in a year
= 250 × 0.7 × 8760 = 1533000 kWh
Annual bill = Max demand charges + energy charges
= (294.11 × 50) + (1533000 × 0.1) = Rs. 168005.5
When the spacing between the conductors in an overhead line is increased- a)The line inductance decreases but the capacitance increases
- b)The line capacitance decreases but the inductance increases
- c)Both the inductance and the capacitance decreases
- d)Both the inductance and the capacitance increases
Correct answer is option 'B'. Can you explain this answer?
When the spacing between the conductors in an overhead line is increased
a)
The line inductance decreases but the capacitance increases
b)
The line capacitance decreases but the inductance increases
c)
Both the inductance and the capacitance decreases
d)
Both the inductance and the capacitance increases
| | Rajat Kumar answered |
Explanation:
When the spacing between the conductors in an overhead line is increased, the line capacitance decreases but the inductance increases. This is due to the following reasons:
1. Capacitance:
- The capacitance of a transmission line is primarily determined by the spacing between the conductors.
- When the spacing between the conductors is increased, the electric field between them is weakened, resulting in a decrease in capacitance.
- The capacitance between the conductors is given by the equation C = εA/d, where C is the capacitance, ε is the permittivity of the medium between the conductors, A is the area of overlap between the conductors, and d is the distance between the conductors.
- As the distance between the conductors increases, the capacitance decreases because the area of overlap decreases.
2. Inductance:
- The inductance of a transmission line is primarily determined by the spacing between the conductors and the arrangement of the conductors.
- When the spacing between the conductors is increased, the magnetic field between them is strengthened, resulting in an increase in inductance.
- The inductance of a transmission line is given by the equation L = μl/2π ln(D/d), where L is the inductance, μ is the permeability of the medium between the conductors, l is the length of the line, D is the diameter of the conductor, and d is the distance between the conductors.
- As the distance between the conductors increases, the inductance increases because the natural logarithm term in the equation increases.
Conclusion:
Based on the above explanations, when the spacing between the conductors in an overhead line is increased, the line capacitance decreases but the inductance increases. This is due to the weakening of the electric field and strengthening of the magnetic field between the conductors.
When the spacing between the conductors in an overhead line is increased, the line capacitance decreases but the inductance increases. This is due to the following reasons:
1. Capacitance:
- The capacitance of a transmission line is primarily determined by the spacing between the conductors.
- When the spacing between the conductors is increased, the electric field between them is weakened, resulting in a decrease in capacitance.
- The capacitance between the conductors is given by the equation C = εA/d, where C is the capacitance, ε is the permittivity of the medium between the conductors, A is the area of overlap between the conductors, and d is the distance between the conductors.
- As the distance between the conductors increases, the capacitance decreases because the area of overlap decreases.
2. Inductance:
- The inductance of a transmission line is primarily determined by the spacing between the conductors and the arrangement of the conductors.
- When the spacing between the conductors is increased, the magnetic field between them is strengthened, resulting in an increase in inductance.
- The inductance of a transmission line is given by the equation L = μl/2π ln(D/d), where L is the inductance, μ is the permeability of the medium between the conductors, l is the length of the line, D is the diameter of the conductor, and d is the distance between the conductors.
- As the distance between the conductors increases, the inductance increases because the natural logarithm term in the equation increases.
Conclusion:
Based on the above explanations, when the spacing between the conductors in an overhead line is increased, the line capacitance decreases but the inductance increases. This is due to the weakening of the electric field and strengthening of the magnetic field between the conductors.
Surge protector provides- a)Low impedance to normal voltage only
- b)High impedance to surge only
- c)High impedance to normal voltage and low impedance to surge
- d)Both 1 and 2 above
Correct answer is option 'C'. Can you explain this answer?
Surge protector provides
a)
Low impedance to normal voltage only
b)
High impedance to surge only
c)
High impedance to normal voltage and low impedance to surge
d)
Both 1 and 2 above
 | Sanjana Chopra answered |
Understanding Surge Protectors
Surge protectors are crucial devices designed to protect electrical equipment from voltage spikes. To grasp why option 'C' is the correct answer, it's essential to understand how surge protectors function regarding impedance.
Impedance Characteristics
- Normal Voltage:
Surge protectors maintain a high impedance to normal operating voltage. This means that during regular conditions, they do not interfere with the electrical flow, allowing devices to function normally.
- Surge Voltage:
Conversely, surge protectors exhibit low impedance when a voltage surge occurs. This allows excess voltage to be diverted away from sensitive equipment, preventing damage.
Why Option 'C' is Correct
- High Impedance to Normal Voltage:
Surge protectors do not impede the normal voltage; hence, devices can operate efficiently without power loss or disruption.
- Low Impedance to Surge:
During a surge, the low impedance path enables the surge protector to channel the excess energy away, thereby protecting the connected devices.
Conclusion
In summary, surge protectors are designed to have high impedance under normal working conditions and low impedance during surges. This dual characteristic ensures the protection of electrical devices while maintaining their regular operation. Thus, option 'C' accurately represents the operational principles of surge protectors.
Surge protectors are crucial devices designed to protect electrical equipment from voltage spikes. To grasp why option 'C' is the correct answer, it's essential to understand how surge protectors function regarding impedance.
Impedance Characteristics
- Normal Voltage:
Surge protectors maintain a high impedance to normal operating voltage. This means that during regular conditions, they do not interfere with the electrical flow, allowing devices to function normally.
- Surge Voltage:
Conversely, surge protectors exhibit low impedance when a voltage surge occurs. This allows excess voltage to be diverted away from sensitive equipment, preventing damage.
Why Option 'C' is Correct
- High Impedance to Normal Voltage:
Surge protectors do not impede the normal voltage; hence, devices can operate efficiently without power loss or disruption.
- Low Impedance to Surge:
During a surge, the low impedance path enables the surge protector to channel the excess energy away, thereby protecting the connected devices.
Conclusion
In summary, surge protectors are designed to have high impedance under normal working conditions and low impedance during surges. This dual characteristic ensures the protection of electrical devices while maintaining their regular operation. Thus, option 'C' accurately represents the operational principles of surge protectors.
In differential protection of busbars, the CT ratio is- a)Based on total expected fault current
- b)Equal and based on primary current of lowest current carrying feeder
- c)Based on their respective feeder current
- d)is based on primary current input to secondary current output at full load.
Correct answer is option 'D'. Can you explain this answer?
In differential protection of busbars, the CT ratio is
a)
Based on total expected fault current
b)
Equal and based on primary current of lowest current carrying feeder
c)
Based on their respective feeder current
d)
is based on primary current input to secondary current output at full load.
 | Baishali Bajaj answered |
In early days only conventional over current relays were used for busbar protection. But it is desired that fault in any feeder or transformer connected to the busbar should not disturb busbar system. In viewing of this time setting of busbar protection relays are made lengthy. So when faults occurs on busbar itself, it takes much time to isolate the bus from source which may came much damage in the bus system.
In recent days, the second zone distance protection relays on incoming feeder, with operating time of 0.3 to 0.5 seconds have been applied for busbar protection.
But this scheme has also a main disadvantage. This scheme of protection can not discriminate the faulty section of the busbar.
Now days, electrical power system deals with huge amount of power. Hence any interruption in total bus system causes big loss to the company. So it becomes essential to isolate only faulty section of busbar during bus fault.
For Average values of load current, current chopping occurs more frequently in- a)ACB’s
- b)SF6 CB’s
- c)VCB’s
- d)OCB’s
Correct answer is option 'A'. Can you explain this answer?
For Average values of load current, current chopping occurs more frequently in
a)
ACB’s
b)
SF6 CB’s
c)
VCB’s
d)
OCB’s
| | Simran Mukherjee answered |
When low inductive currents such as magnetizing current of transformer, shunt reactors are interrupted by breaker, there is rapid deionization of contact space and may cause the current to be interrupted before its neutral zero. This phenomena is called current chopping. For average values of load current, it occurs frequently in Air blast circuit breakers.
The effect of wind pressure is more predominant - a)Supporting tower
- b)Neutral wires
- c)Transmission lines
- d)Insulators
Correct answer is option 'A'. Can you explain this answer?
The effect of wind pressure is more predominant
a)
Supporting tower
b)
Neutral wires
c)
Transmission lines
d)
Insulators
| | Janhavi Roy answered |
Supporting tower:
Wind pressure has a more predominant effect on supporting towers compared to other components of a transmission line system. Supporting towers are tall structures that bear the weight of the transmission lines and are exposed to the full force of wind. The wind exerts pressure on the tower, causing it to sway or vibrate. This can lead to structural fatigue and, in extreme cases, tower failure. Proper design and reinforcement of supporting towers are essential to ensure the stability and longevity of the transmission line system.
Neutral wires, Transmission lines, and Insulators:
While wind pressure can also impact neutral wires, transmission lines, and insulators, their design and placement are typically less affected by wind compared to supporting towers. Neutral wires are usually smaller in diameter and are designed to carry minimal current, so the impact of wind pressure on them is relatively minor. Transmission lines are often designed with sufficient clearance from the ground and other structures to minimize the effects of wind. Insulators are also designed to withstand mechanical stresses, including those caused by wind, but they are less susceptible to wind pressure compared to supporting towers.
In conclusion, supporting towers are the components of a transmission line system that are most affected by wind pressure. Proper design, maintenance, and reinforcement of supporting towers are crucial to ensure the reliability and safety of the transmission line system.
When feeder ring distributes energy from two or more than two production plants, then this distribution system is known as:- a)Radial system
- b)Ring main system
- c)Interconnected system
- d)Underground system
Correct answer is option 'C'. Can you explain this answer?
When feeder ring distributes energy from two or more than two production plants, then this distribution system is known as:
a)
Radial system
b)
Ring main system
c)
Interconnected system
d)
Underground system
| | Snehal Rane answered |
Interconnected System
An interconnected system refers to a distribution system where energy is distributed from two or more production plants through a feeder ring. This system is commonly used in electrical power systems to ensure reliability and redundancy in the supply of electricity. Let's explore the characteristics and advantages of an interconnected system.
Characteristics of an Interconnected System:
1. Feeder Ring: In an interconnected system, a feeder ring is used to distribute energy from multiple production plants. The feeder ring is a closed loop network that connects the production plants, allowing for the transfer of power between them.
2. Multiple Sources: The interconnected system utilizes two or more production plants as sources of energy. This arrangement ensures that if one plant experiences an outage or maintenance, the other plants can continue supplying power, ensuring uninterrupted electricity supply.
3. Redundancy: The use of multiple production plants in the interconnected system provides redundancy. If one plant fails, the other plants can compensate for the loss, ensuring a reliable supply of electricity to consumers.
Advantages of an Interconnected System:
1. Increased Reliability: The interconnected system enhances the reliability of the electrical distribution system by providing multiple sources of power. This reduces the chances of power outages and ensures uninterrupted electricity supply to consumers.
2. Flexibility: With an interconnected system, power can be easily transferred between production plants. This flexibility allows for load balancing and optimized utilization of available resources, leading to efficient operation of the electrical distribution system.
3. Load Sharing: The interconnected system enables load sharing among the production plants. When one plant is operating at maximum capacity, the excess load can be shifted to other plants, preventing overloading and ensuring that each plant operates within its safe limits.
4. Maintenance and Outage Management: An interconnected system allows for easier maintenance and outage management. If a production plant requires maintenance or experiences an outage, the load can be transferred to other plants without interrupting the supply to consumers.
Conclusion:
An interconnected system is a distribution system that utilizes a feeder ring to distribute energy from two or more production plants. This system enhances the reliability, flexibility, and efficiency of the electrical distribution system by providing redundancy, load sharing, and easy maintenance and outage management. It ensures uninterrupted power supply to consumers and is widely used in electrical power systems.
An interconnected system refers to a distribution system where energy is distributed from two or more production plants through a feeder ring. This system is commonly used in electrical power systems to ensure reliability and redundancy in the supply of electricity. Let's explore the characteristics and advantages of an interconnected system.
Characteristics of an Interconnected System:
1. Feeder Ring: In an interconnected system, a feeder ring is used to distribute energy from multiple production plants. The feeder ring is a closed loop network that connects the production plants, allowing for the transfer of power between them.
2. Multiple Sources: The interconnected system utilizes two or more production plants as sources of energy. This arrangement ensures that if one plant experiences an outage or maintenance, the other plants can continue supplying power, ensuring uninterrupted electricity supply.
3. Redundancy: The use of multiple production plants in the interconnected system provides redundancy. If one plant fails, the other plants can compensate for the loss, ensuring a reliable supply of electricity to consumers.
Advantages of an Interconnected System:
1. Increased Reliability: The interconnected system enhances the reliability of the electrical distribution system by providing multiple sources of power. This reduces the chances of power outages and ensures uninterrupted electricity supply to consumers.
2. Flexibility: With an interconnected system, power can be easily transferred between production plants. This flexibility allows for load balancing and optimized utilization of available resources, leading to efficient operation of the electrical distribution system.
3. Load Sharing: The interconnected system enables load sharing among the production plants. When one plant is operating at maximum capacity, the excess load can be shifted to other plants, preventing overloading and ensuring that each plant operates within its safe limits.
4. Maintenance and Outage Management: An interconnected system allows for easier maintenance and outage management. If a production plant requires maintenance or experiences an outage, the load can be transferred to other plants without interrupting the supply to consumers.
Conclusion:
An interconnected system is a distribution system that utilizes a feeder ring to distribute energy from two or more production plants. This system enhances the reliability, flexibility, and efficiency of the electrical distribution system by providing redundancy, load sharing, and easy maintenance and outage management. It ensures uninterrupted power supply to consumers and is widely used in electrical power systems.
The most suitable circuit breaker for interrupting short line fault without resistance switching is:- a)Minimum oil circuit breaker
- b)SF6 circuit breaker
- c)Bulk oil circuit breaker
- d)Air blast circuit breaker
Correct answer is option 'B'. Can you explain this answer?
The most suitable circuit breaker for interrupting short line fault without resistance switching is:
a)
Minimum oil circuit breaker
b)
SF6 circuit breaker
c)
Bulk oil circuit breaker
d)
Air blast circuit breaker
| | Mihir Chawla answered |
A fixed connection of resistance in parallel with the contact space or arc is called the resistance switching. Resistance switching is employed in circuit breakers having a high post zero resistance of contact space. The resistance switching is mainly used for reducing the re-striking voltage and the transient voltage surge.
SF6 circuit breaker is most suitable for interrupting short line fault without resistance switching.
________ does not have any repairable component:- a)Air Blast CB
- b)MCB
- c)OCB
- d)Air Break
Correct answer is option 'B'. Can you explain this answer?
________ does not have any repairable component:
a)
Air Blast CB
b)
MCB
c)
OCB
d)
Air Break
| | Alok Khanna answered |
MCB (miniature circuit breaker) is an electromechanical device which guards an electrical circuit from an over current that may effect from short circuit, overload or imperfect design. It doesn’t have any repairable component.
MCB is substituting the rewirable switch-fuse units for low power domestic and industrial applications in a very quick manner. In wiring system, the MCB is a blend of all three functions such as protection of short circuit, overload and switching. Protection of overload by using a bimetallic strip and short circuit protection by using solenoid
Capacitors and Reactors are used in transmission system to control voltage as given below. Select the correct choice:- a)Series capacitors and shunt reactors for loading power factor
- b)Shunt capacitors when – power factors leading and series reactors when power factor lagging
- c)Shunt capacitors when power factors lagging and series reactors when power factor is leading
- d)Shunt capacitors and series reactors for leading power factors
Correct answer is option 'C'. Can you explain this answer?
Capacitors and Reactors are used in transmission system to control voltage as given below. Select the correct choice:
a)
Series capacitors and shunt reactors for loading power factor
b)
Shunt capacitors when – power factors leading and series reactors when power factor lagging
c)
Shunt capacitors when power factors lagging and series reactors when power factor is leading
d)
Shunt capacitors and series reactors for leading power factors
| | Ankita Das answered |
Whenever an inductive load is connected to the transmission line, power factor lags because of lagging load current. To compensate this, a shunt capacitor is connected which draws current leading the source voltage. The power factor can be improved.
Series capacitors are used to compensate the inductance of transmission line. They will increase the transmission capacity and the stability of the line. These are also used to share the load between parallel lines.
Series reactors are used as current limiting reactors to increase the impedance of a system. They are also used to limit the starting currents of synchronous electric motors and to compensate reactive power in order to improve the transmission capacity of power lines.
A shunt reactor is an absorber of reactive power, thus increasing the energy efficiency of the system.
Two areas A and B have equal connected loads however load diversity in area A is more than in B then:- a)Maximum demand of two areas is small
- b)Maximum demand of A is greater than maximum demand of B
- c)Maximum demand of B is greater than maximum demand of A
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
Two areas A and B have equal connected loads however load diversity in area A is more than in B then:
a)
Maximum demand of two areas is small
b)
Maximum demand of A is greater than maximum demand of B
c)
Maximum demand of B is greater than maximum demand of A
d)
None of these
| | Ashwin Kapoor answered |
Diversity factor is the ratio of the sum of the maximum demands of a group of consumers and the simultaneous maximum demand of the group of consumers
Diversity factor = connected load/maximum demand
Given that connected load is same for both A and B
Then, diversity factor is inversely proportional to maximum demand
Given that diversity factor in area A is more hence maximum demand of A is less than maximum demand of B
Fusing current is the :- a)Maximum current at which the fuse element will get heated
- b)Rated current of a fuse
- c)The minimum current at which the fuse element will get heated
- d)The minimum current at which the fuse element will melt
Correct answer is option 'D'. Can you explain this answer?
Fusing current is the :
a)
Maximum current at which the fuse element will get heated
b)
Rated current of a fuse
c)
The minimum current at which the fuse element will get heated
d)
The minimum current at which the fuse element will melt
 | Megha Datta answered |
A fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby interrupting the current. The minimum current at which the fuse element will melt is called as fusing current
Load curve helps in deciding:- a)The total installed capacity of the plant
- b)The size of the generating units
- c)The operating schedule of the generating units
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Load curve helps in deciding:
a)
The total installed capacity of the plant
b)
The size of the generating units
c)
The operating schedule of the generating units
d)
All of the above
| | Anmol Menon answered |
A load curve is a plot of the load demand with respect to the time in the chronological order
From the load curve, the following information can be obtained
1) The variation of load on the power system during different hours of the day
2) Number of units generated
3) The highest point in the curve indicates the maximum demand on the power station
4) The area of the curve divided by time gives the average load on the power station
By observing the above information, it helps in deciding
1. The total installed capacity of the plant
2. The size of the generating units
3. The operating schedule of the generating units
Which of the following is true with respect to a breeder reactor?- a)Its conversion ratio is greater than 1
- b)It is capable of generating more fissile material than it consumes
- c)Both A and B
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
Which of the following is true with respect to a breeder reactor?
a)
Its conversion ratio is greater than 1
b)
It is capable of generating more fissile material than it consumes
c)
Both A and B
d)
None of these
| | Alok Roy answered |
A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These devices achieve this because their neutron economy is high enough to breed more fissile fuel than they use from the fertile material, such as uranium-238 or thorium-232. Its conversion ratio is greater than one.
The _________ faults are due to short circuits in conductors.- a)Shunt
- b)Series
- c)Parallel
- d)Fixed
Correct answer is option 'A'. Can you explain this answer?
The _________ faults are due to short circuits in conductors.
a)
Shunt
b)
Series
c)
Parallel
d)
Fixed
| | Poulomi Chopra answered |
The shunt fault involves short circuit between conductor and ground or short circuit between two or more conductors.
The shunt faults are characterized by increase in current and fall in voltage and frequency.
Shunt faults are classified as follows:
1) Single line to Ground fault (LG fault)
2) Line to Line fault (LL fault)
3) Double line to Ground fault (LLG fault)
4) Three phase fault
The non-uniform distribution of voltage across the units in a string of suspension insulators is due to:- a)Unequal self-capacitance of the units
- b)The existence of stray capacitance between the metallic junctions of the units and the tower body
- c)Non uniform distance of separation of the units the tower body
- d)Non uniform distance of between the cross arm and the units
Correct answer is option 'B'. Can you explain this answer?
The non-uniform distribution of voltage across the units in a string of suspension insulators is due to:
a)
Unequal self-capacitance of the units
b)
The existence of stray capacitance between the metallic junctions of the units and the tower body
c)
Non uniform distance of separation of the units the tower body
d)
Non uniform distance of between the cross arm and the units
| | Prasenjit Yadav answered |
Important points regarding the voltage distribution over a string of suspension insulators:
1) Due to the presence of shunt capacitor, the voltage across the suspension insulators does not distribute itself uniformly across the each disc.
2) The voltage across the nearest disc to the conductor is maximum than others disc.
3) The unit nearest to the conductor is under maximum electrical stress and is likely to be punctured.
4) In the case of D.C voltage, the voltage across each unit would be the same. It is because insulator capacitance are ineffective for D.C.
Consider the following statementsHigh voltage is used in long distance power transmission in order to:1) Reduce the time of transmission2) Reduce the transmission losses3) Make the system reliableOut of these, the correct statements are?- a)Only B
- b)Only A and C
- c)Only A and B
- d)All three
Correct answer is option 'D'. Can you explain this answer?
Consider the following statements
High voltage is used in long distance power transmission in order to:
1) Reduce the time of transmission
2) Reduce the transmission losses
3) Make the system reliable
Out of these, the correct statements are?
a)
Only B
b)
Only A and C
c)
Only A and B
d)
All three
| | Nilesh Verma answered |
High voltage is used in long distance power transmission in order to
1) Reduce the time of transmission
2) Reduce the transmission losses
3) Make the system reliable
In an AC transmission line difference in phase of voltage at two ends of the line is due to- a)System voltage
- b)Insulators
- c)Resistance of line
- d)Reactance of line
Correct answer is option 'D'. Can you explain this answer?
In an AC transmission line difference in phase of voltage at two ends of the line is due to
a)
System voltage
b)
Insulators
c)
Resistance of line
d)
Reactance of line
| | Mahi Bose answered |
In an AC transmission line, difference in phase of voltage at two ends of the line is due to the inductive and capacitive reactance of the transmission lines.
Power plant having maximum demand more than installed capacity will have utilization factor:- a)Less than 100%
- b)Equal to 100%
- c)More than 100%
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
Power plant having maximum demand more than installed capacity will have utilization factor:
a)
Less than 100%
b)
Equal to 100%
c)
More than 100%
d)
None of these
 | Sakshi Roy answered |
If maximum demand is more than installed capacity, station output will be more than the installed plant capacity.
Hence utilization factor will be more than 100%
For increasing the limit of distance of transmission line,- a)Series resistance are used
- b)Synchronous condensers are used
- c)Series capacitors and shunt reactors are used
- d)Shunt capacitors and shunt reactors are used
Correct answer is option 'C'. Can you explain this answer?
For increasing the limit of distance of transmission line,
a)
Series resistance are used
b)
Synchronous condensers are used
c)
Series capacitors and shunt reactors are used
d)
Shunt capacitors and shunt reactors are used
| | Sharmila Bajaj answered |
Series capacitors are used to compensate the inductance of transmission line. They will increase the transmission capacity and the stability of the line. These are also used to share the load between parallel lines.
A shunt reactor is an absorber of reactive power, thus increasing the energy efficiency of the system.
Cables in power transmission line are provided with inter sheaths to:- a)Minimize charging current
- b)Minimize stress
- c)Provide uniform stress distribution
- d)Minimize high voltage
Correct answer is option 'C'. Can you explain this answer?
Cables in power transmission line are provided with inter sheaths to:
a)
Minimize charging current
b)
Minimize stress
c)
Provide uniform stress distribution
d)
Minimize high voltage
| | Sakshi Roy answered |
Cables in power transmission line are provided with inter sheaths to provide proper distribution of stress.
Relay using Induction disk principle operate:- a)Only on D.C.
- b)Only on A.C.
- c)Either D.C. ad A.C.
- d)None of these
Correct answer is option 'B'. Can you explain this answer?
Relay using Induction disk principle operate:
a)
Only on D.C.
b)
Only on A.C.
c)
Either D.C. ad A.C.
d)
None of these
| | Dipika Basak answered |
Introduction:
A relay is an electrically operated switch that uses an electromagnet to mechanically control the opening and closing of its contacts. It is commonly used in various applications to control high-power circuits with low-power signals. Relays can operate on both direct current (DC) and alternating current (AC) depending on their design and construction.
Explanation:
Relays can be classified into different types based on their operating principles, and one of the commonly used types is an induction disk relay. This type of relay operates on AC power only.
Induction Disk Principle:
The induction disk principle is based on the interaction between a rotating disk and a magnetic field. The relay consists of a rotor disk made of conductive material that is free to rotate between the poles of an electromagnet. The rotating disk is mounted on a spindle and is connected to the relay contacts.
Operating Mechanism:
When an AC voltage is applied to the coil of the electromagnet, it generates a magnetic field that alternates in polarity with the frequency of the AC supply. This alternating magnetic field induces eddy currents in the rotating disk. As a result, a torque is produced on the disk, causing it to rotate.
Direction of Rotation:
The direction of rotation of the disk depends on the direction of the magnetic field and the eddy currents induced in the disk. The rotation of the disk is either clockwise or counterclockwise, depending on the design of the relay.
Contact Operation:
The rotation of the disk is mechanically linked to the relay contacts, causing them to open or close depending on the position of the disk. When the disk rotates to a certain position, the contacts are either opened or closed, allowing or interrupting the flow of current in the controlled circuit.
Advantages and Limitations:
The induction disk principle offers several advantages, such as reliable operation, high-speed switching, and ability to handle high currents. However, it is limited to AC operation only and cannot be used with DC power due to the absence of alternating magnetic fields necessary for inducing eddy currents in the disk.
Conclusion:
In conclusion, a relay using the induction disk principle operates only on AC power. It utilizes the interaction between a rotating disk and an alternating magnetic field to control the opening and closing of its contacts. This type of relay offers reliable and high-speed switching but is limited to AC applications only.
A relay is an electrically operated switch that uses an electromagnet to mechanically control the opening and closing of its contacts. It is commonly used in various applications to control high-power circuits with low-power signals. Relays can operate on both direct current (DC) and alternating current (AC) depending on their design and construction.
Explanation:
Relays can be classified into different types based on their operating principles, and one of the commonly used types is an induction disk relay. This type of relay operates on AC power only.
Induction Disk Principle:
The induction disk principle is based on the interaction between a rotating disk and a magnetic field. The relay consists of a rotor disk made of conductive material that is free to rotate between the poles of an electromagnet. The rotating disk is mounted on a spindle and is connected to the relay contacts.
Operating Mechanism:
When an AC voltage is applied to the coil of the electromagnet, it generates a magnetic field that alternates in polarity with the frequency of the AC supply. This alternating magnetic field induces eddy currents in the rotating disk. As a result, a torque is produced on the disk, causing it to rotate.
Direction of Rotation:
The direction of rotation of the disk depends on the direction of the magnetic field and the eddy currents induced in the disk. The rotation of the disk is either clockwise or counterclockwise, depending on the design of the relay.
Contact Operation:
The rotation of the disk is mechanically linked to the relay contacts, causing them to open or close depending on the position of the disk. When the disk rotates to a certain position, the contacts are either opened or closed, allowing or interrupting the flow of current in the controlled circuit.
Advantages and Limitations:
The induction disk principle offers several advantages, such as reliable operation, high-speed switching, and ability to handle high currents. However, it is limited to AC operation only and cannot be used with DC power due to the absence of alternating magnetic fields necessary for inducing eddy currents in the disk.
Conclusion:
In conclusion, a relay using the induction disk principle operates only on AC power. It utilizes the interaction between a rotating disk and an alternating magnetic field to control the opening and closing of its contacts. This type of relay offers reliable and high-speed switching but is limited to AC applications only.
Which of the following is not a kind of relay on the basis of constructional features?- a)Moving iron type
- b)Static
- c)Induction
- d)Current
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not a kind of relay on the basis of constructional features?
a)
Moving iron type
b)
Static
c)
Induction
d)
Current
| | Sharmila Kulkarni answered |
Introduction:
In electrical engineering, relays are widely used devices that control electrical circuits by opening and closing contacts electromechanically or electronically. They are classified based on various factors, including their constructional features. This question is asking us to identify the type of relay that is not based on constructional features.
Moving Iron Type Relay:
- Moving iron type relays have a movable iron armature and a fixed coil.
- The armature moves when the coil is energized, and this movement is used to open or close the contacts of the relay.
- These relays are commonly used for AC circuits and are suitable for both high and low currents.
Static Relay:
- Static relays do not have any moving parts.
- They use solid-state components such as transistors, diodes, and operational amplifiers to perform the relay function.
- Static relays are faster, more reliable, and have a longer lifespan compared to electromechanical relays.
- They are commonly used in applications where high-speed operation, precise control, and immunity to mechanical wear and tear are required.
Induction Relay:
- Induction relays use the principle of electromagnetic induction to operate.
- They consist of a coil and an iron core that create a magnetic field when energized.
- The magnetic field induces eddy currents in a conducting disc or a cup-shaped rotor, causing it to move and operate the relay contacts.
- Induction relays are commonly used in protective relaying applications, such as overcurrent and distance relays.
Current Relay:
- Current relay is not a specific type of relay based on constructional features.
- It is a generic term used to describe relays that operate based on the magnitude of current flowing through them.
- Current relays can be of various types, such as overcurrent relays, undercurrent relays, differential relays, etc.
- The constructional features of a current relay can vary depending on its specific application and design.
Conclusion:
Based on the above discussion, the correct answer is option 'D' - Current. Current relay is not a specific type of relay based on constructional features, but rather a general term used to describe relays that operate based on current magnitude. The other options, moving iron type relay, static relay, and induction relay, are all specific types of relays based on their constructional features.
In electrical engineering, relays are widely used devices that control electrical circuits by opening and closing contacts electromechanically or electronically. They are classified based on various factors, including their constructional features. This question is asking us to identify the type of relay that is not based on constructional features.
Moving Iron Type Relay:
- Moving iron type relays have a movable iron armature and a fixed coil.
- The armature moves when the coil is energized, and this movement is used to open or close the contacts of the relay.
- These relays are commonly used for AC circuits and are suitable for both high and low currents.
Static Relay:
- Static relays do not have any moving parts.
- They use solid-state components such as transistors, diodes, and operational amplifiers to perform the relay function.
- Static relays are faster, more reliable, and have a longer lifespan compared to electromechanical relays.
- They are commonly used in applications where high-speed operation, precise control, and immunity to mechanical wear and tear are required.
Induction Relay:
- Induction relays use the principle of electromagnetic induction to operate.
- They consist of a coil and an iron core that create a magnetic field when energized.
- The magnetic field induces eddy currents in a conducting disc or a cup-shaped rotor, causing it to move and operate the relay contacts.
- Induction relays are commonly used in protective relaying applications, such as overcurrent and distance relays.
Current Relay:
- Current relay is not a specific type of relay based on constructional features.
- It is a generic term used to describe relays that operate based on the magnitude of current flowing through them.
- Current relays can be of various types, such as overcurrent relays, undercurrent relays, differential relays, etc.
- The constructional features of a current relay can vary depending on its specific application and design.
Conclusion:
Based on the above discussion, the correct answer is option 'D' - Current. Current relay is not a specific type of relay based on constructional features, but rather a general term used to describe relays that operate based on current magnitude. The other options, moving iron type relay, static relay, and induction relay, are all specific types of relays based on their constructional features.
The current in a transmission line under no load conditions is due to:- a)Spinning reserve
- b)Corona effects
- c)Capacitance of the line
- d)Back flow from earth
Correct answer is option 'C'. Can you explain this answer?
The current in a transmission line under no load conditions is due to:
a)
Spinning reserve
b)
Corona effects
c)
Capacitance of the line
d)
Back flow from earth
| | Dhruv Datta answered |
Capacitance of the line:
The current in a transmission line under no load conditions is primarily due to the capacitance of the line. This capacitance allows for the storage of electric charge, which can result in a small current flow even when there is no external load connected to the line.
Explanation:
- When a transmission line is energized, the conductors and the insulating material between them form a capacitor.
- This capacitance allows for the accumulation of electric charge, creating an electric field between the conductors.
- Even in the absence of a load, this electric field can cause a small current to flow through the line due to the displacement of charges within the capacitance of the line.
- This current is typically very small and is known as the capacitive current.
Significance:
- The presence of capacitance in transmission lines can have implications for overall system performance and efficiency.
- It can impact the power factor of the system and can lead to losses in the form of reactive power.
- It is important for system operators to account for capacitance when designing and operating transmission lines to ensure optimal performance and efficiency.
The current in a transmission line under no load conditions is primarily due to the capacitance of the line. This capacitance allows for the storage of electric charge, which can result in a small current flow even when there is no external load connected to the line.
Explanation:
- When a transmission line is energized, the conductors and the insulating material between them form a capacitor.
- This capacitance allows for the accumulation of electric charge, creating an electric field between the conductors.
- Even in the absence of a load, this electric field can cause a small current to flow through the line due to the displacement of charges within the capacitance of the line.
- This current is typically very small and is known as the capacitive current.
Significance:
- The presence of capacitance in transmission lines can have implications for overall system performance and efficiency.
- It can impact the power factor of the system and can lead to losses in the form of reactive power.
- It is important for system operators to account for capacitance when designing and operating transmission lines to ensure optimal performance and efficiency.
Radial system is used when:- a)Energy is to be produced on high potential
- b)Energy is to be produced on low potential
- c)Sub station is far away from load station
- d)Number of consumers are more
Correct answer is option 'B'. Can you explain this answer?
Radial system is used when:
a)
Energy is to be produced on high potential
b)
Energy is to be produced on low potential
c)
Sub station is far away from load station
d)
Number of consumers are more
| | Gayatri Menon answered |
In radial distribution system, different feeders radially came out from the substation and connected to the primary of distribution transformer.
It is cheapest to build, and is widely used in sparsely populated areas. A radial system has only one power source for a group of customers. A power failure, short-circuit, or a downed power line would interrupt power in the entire line which must be fixed before power can be restored.
Hence it is used when energy is to be produced on low potential.
What are the advantages of DC transmission system over AC transmission system?- a)DC System is economical for long time
- b)There is no skin effect in DC system
- c)Corona limits are highest of DC circuit as compared to AC circuit
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
What are the advantages of DC transmission system over AC transmission system?
a)
DC System is economical for long time
b)
There is no skin effect in DC system
c)
Corona limits are highest of DC circuit as compared to AC circuit
d)
All of the above
| | Prerna Tiwari answered |
The advantages of DC transmission system over AC transmission system are:
1) DC system is economical for long line
2) DC needs only two wires of transmission, while a 3 phase AC may need up to 4 wires
3) The corona loss is absent in DC, while for AC it increases with its frequency
4) The skin effect is also observed in AC, leading to problems in transmission conductor designs
5) No inductive and capacitive losses
6) No proximity effect
The most commonly used insulation for cables in the low voltage to 33 kV range is:- a)Paper insulation
- b)Cross linked polyethylene
- c)Vulcanised India rubber
- d)Poly vinyl chloride
Correct answer is option 'C'. Can you explain this answer?
The most commonly used insulation for cables in the low voltage to 33 kV range is:
a)
Paper insulation
b)
Cross linked polyethylene
c)
Vulcanised India rubber
d)
Poly vinyl chloride
| | Nayanika Kaur answered |
Because of the following benefits we use cross linked polyethylene as insulation for cables.
1) Works with a variety of voltage ranges 600 V to 35 kV
2) Provides mechanical protection
3) Can withstand extreme pressure
4) Resists underground damage
5) Weather resistant
6) Thermal resistant
7) Permits high conductor operating temperatures
8) Reduces short circuit and overload levels
8) Moisture resistant
What are Oil switches used for?- a)Low current circuits
- b)Low voltage circuits
- c)High voltage and large current circuits
- d)Low current supply
Correct answer is option 'C'. Can you explain this answer?
What are Oil switches used for?
a)
Low current circuits
b)
Low voltage circuits
c)
High voltage and large current circuits
d)
Low current supply
| | Puja Shah answered |
Oil switches: As the name implies, the contacts of switches are opened under oil. Usually transformer oil is used whose purpose is to cool and quench the arc formed on account of opening the contacts. These switches are used for circuits of high voltage and large current carrying capacities.
Air break switches are generally used outdoors for circuits of medium capacity such as lines supplying an industrial load from a main transmission line or feeder
In the analysis of short transmission lines, which of the following is neglected?- a)I2R loss
- b)Shunt capacitance
- c)Series impedance
- d)All of the above
Correct answer is option 'B'. Can you explain this answer?
In the analysis of short transmission lines, which of the following is neglected?
a)
I2R loss
b)
Shunt capacitance
c)
Series impedance
d)
All of the above
| | Puja Shah answered |
The transmission lines which have length less than 50 km are generally referred as short transmission lines.
For short length, the shunt capacitance of this type of line is neglected and other parameters like electrical resistance and inductance are lumped
Which of the following relay, operates when current exceeds a present value?- a)Over current relay
- b)Differential relay
- c)Static relay
- d)Instantaneous relay
Correct answer is option 'A'. Can you explain this answer?
Which of the following relay, operates when current exceeds a present value?
a)
Over current relay
b)
Differential relay
c)
Static relay
d)
Instantaneous relay
| | Gayatri Menon answered |
Over current relay: It operates or picks up when its current exceeds a predetermined value (setting value). It protects electrical power systems against excessive currents which are caused by short circuits, ground faults, etc.
Differential relay: It is defined as the relay that operates when the phase difference of two or more identical electrical quantities exceeds a predetermined amount. The differential relay works on the principle of comparison between the phase angle and magnitude of two or more similar electrical quantities.
Static relay: The relay which does not contain any moving parts is known as the static relay. In such type of relays, the output is obtained by the static components like magnetic and electronic circuit etc.
A radial power system is represented by- - a)Closed paths
- b)Closed and open paths
- c)Only open paths
- d)None of the other options
Correct answer is option 'C'. Can you explain this answer?
A radial power system is represented by-
a)
Closed paths
b)
Closed and open paths
c)
Only open paths
d)
None of the other options
 | Sandeep Chatterjee answered |
Radial Power System:
A radial power system is a type of electrical power distribution system in which power flows in one direction, from a single source to multiple loads. It is characterized by a single feed point or source, with distribution lines branching out to supply power to various loads.
Representation of Radial Power System:
The representation of a radial power system depends on the paths through which power flows. The given options for representing a radial power system are as follows:
a) Closed paths:
Closed paths refer to the presence of multiple interconnected loops or circuits within the power system. In a radial system, power flows in a single direction, and there are no closed loops or paths. Therefore, closed paths do not represent a radial power system.
b) Closed and open paths:
Closed and open paths represent a combination of interconnected loops and unidirectional flow. In a radial power system, power flows in a single direction, and there are no closed loops or paths. Therefore, closed and open paths do not represent a radial power system.
c) Only open paths:
Only open paths represent a unidirectional flow of power without any closed loops or interconnected paths. In a radial power system, power flows from a single source to multiple loads without any feedback or loops. Therefore, only open paths accurately represent a radial power system.
d) None of the other options:
This option suggests that none of the given options accurately represent a radial power system. However, as explained above, only open paths correctly represent the unidirectional flow of power in a radial power system. Therefore, option 'C' (Only open paths) is the correct answer.
In conclusion, a radial power system is represented by only open paths, as power flows in a single direction from a single source to multiple loads without any closed loops or interconnected paths.
A radial power system is a type of electrical power distribution system in which power flows in one direction, from a single source to multiple loads. It is characterized by a single feed point or source, with distribution lines branching out to supply power to various loads.
Representation of Radial Power System:
The representation of a radial power system depends on the paths through which power flows. The given options for representing a radial power system are as follows:
a) Closed paths:
Closed paths refer to the presence of multiple interconnected loops or circuits within the power system. In a radial system, power flows in a single direction, and there are no closed loops or paths. Therefore, closed paths do not represent a radial power system.
b) Closed and open paths:
Closed and open paths represent a combination of interconnected loops and unidirectional flow. In a radial power system, power flows in a single direction, and there are no closed loops or paths. Therefore, closed and open paths do not represent a radial power system.
c) Only open paths:
Only open paths represent a unidirectional flow of power without any closed loops or interconnected paths. In a radial power system, power flows from a single source to multiple loads without any feedback or loops. Therefore, only open paths accurately represent a radial power system.
d) None of the other options:
This option suggests that none of the given options accurately represent a radial power system. However, as explained above, only open paths correctly represent the unidirectional flow of power in a radial power system. Therefore, option 'C' (Only open paths) is the correct answer.
In conclusion, a radial power system is represented by only open paths, as power flows in a single direction from a single source to multiple loads without any closed loops or interconnected paths.
For a fault at terminals of the synchronous generator fault current to be maximum:- a)Three phase fault
- b)Double line to ground fault
- c)Line to line fault
- d)Line to ground fault
Correct answer is option 'D'. Can you explain this answer?
For a fault at terminals of the synchronous generator fault current to be maximum:
a)
Three phase fault
b)
Double line to ground fault
c)
Line to line fault
d)
Line to ground fault
| | Saranya Mishra answered |
For a line to ground fault,
The fault current is three times the line current.
Which of the following is not the correct statement regarding direct current transmission?- a)Corona effect is less
- b)Voltage regulation is good
- c)Skin effect is negligible
- d)There is a continuous power loss
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not the correct statement regarding direct current transmission?
a)
Corona effect is less
b)
Voltage regulation is good
c)
Skin effect is negligible
d)
There is a continuous power loss
| | Shanaya Mehta answered |
1) Corona effect is less in DC transmission compared to AC transmission
2) Voltage regulation is better in case of DC transmission
3) Skin effect is absent in DC transmission, it is more predominant in AC transmission
4) Continuous power losses does not happen in DC transmission
The sag of a transmission line depends upon:- a)Weight of conductor and directly proportional to span length
- b)Weight of conductor and inversely proportional to span length
- c)Weight of conductor and directly proportional to square of span length
- d)Weight of conductor and inversely proportional to square of span length
Correct answer is option 'C'. Can you explain this answer?
The sag of a transmission line depends upon:
a)
Weight of conductor and directly proportional to span length
b)
Weight of conductor and inversely proportional to span length
c)
Weight of conductor and directly proportional to square of span length
d)
Weight of conductor and inversely proportional to square of span length
| | Anshika Nambiar answered |
Sag is defined as the difference in level between points of supports and the lowest point on the conductor.
Sag of conductor’s between two poles can be determined by
Where, S is the sag of conductors
W is the weight per unit length of the conductor
L is the length of span
T is the tension in the conductor
Which of the following method is used for changing power factor from leading to lagging- a)Shunt capacitor
- b)Series capacitor
- c)Shunt reactor
- d)Any of the above
Correct answer is option 'C'. Can you explain this answer?
Which of the following method is used for changing power factor from leading to lagging
a)
Shunt capacitor
b)
Series capacitor
c)
Shunt reactor
d)
Any of the above
| | Arshiya Basu answered |
Under no load condition or light load condition, medium and long transmission lines may operate at leading power factor due to capacitance effect. This leading power factor can be changed to a lagging power factor by using a shunt reactor. By using a shunt reactor, it will compensate the effect of capacitance and changes the power factor.
During current chopping the current actually breaks..- a)During the instant of natural current zero
- b)Before the instant of natural current zero
- c)After the instant of natural current zero
- d)Irrespective of the instant of natural zero
Correct answer is option 'B'. Can you explain this answer?
During current chopping the current actually breaks..
a)
During the instant of natural current zero
b)
Before the instant of natural current zero
c)
After the instant of natural current zero
d)
Irrespective of the instant of natural zero
| | Pranab Chaudhary answered |
Current chopping in circuit breaker is defined as a phenomenon in which current is forcibly interrupted before the natural current zero. Current Chopping is mainly observed in vacuum circuit breaker and air blast circuit breaker. There is no such phenomena in oil circuit breaker. Current chopping is predominant while switching shunt reactor or unloaded transformer.
Generally the arc extinction in a circuit breaker take place at natural current zero. But this is true if the capacity of the breaker to extinguish the arc varies with the level of fault current. This means that, the arc extinction capability of breaker will always ensure that arc extinction is taking place at natural current zero.
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