# Capacitors, Cables, Bus Bars, Test Lab

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Swiftdodgers
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Quizzes Created: 10 | Total Attempts: 8,140
Questions: 41 | Attempts: 684

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• 1.

### What is the effect of series capacitors on a transmission line?

• A.

Shortens the line electrically

• B.

Auxiliary synchronous machines

• C.

Impedance

• D.

Lengthens the line electrically

A. Shortens the line electrically
Explanation
Series capacitors have the effect of shortening the line electrically. This means that they reduce the overall impedance of the transmission line, allowing for more efficient transmission of electrical power. By adding series capacitors, the line becomes more reactive, which helps to compensate for the inductive reactance of the line. This can improve voltage regulation and increase the power transfer capability of the transmission line.

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• 2.

### The purpose of adding series capacitors on a transmission line is to

• A.

Increase flow on the line by decreasing impedance (making line electrically shorter)

• B.

Compensate for the vars produced by the line

• C.

To increase the total vars

• D.

To decrease the total vars

A. Increase flow on the line by decreasing impedance (making line electrically shorter)
Explanation
Adding series capacitors on a transmission line decreases the impedance of the line, which effectively makes the line electrically shorter. This allows for an increase in the flow on the line, as the reduced impedance allows for a higher current to pass through. By decreasing the impedance, the series capacitors help to improve the overall efficiency and performance of the transmission line.

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• 3.

### A dielectric material is mostly a  _____?

• A.

Conductor

• B.

Insulator

• C.

Magnetic field

• D.

Metallic

B. Insulator
Explanation
A dielectric material is mostly an insulator because it does not conduct electricity easily. It has high resistivity and low conductivity, which means it does not allow the flow of electric current through it. Dielectric materials are commonly used in capacitors to store and release electrical energy. They are also used to separate conductive materials and prevent electrical leakage or short-circuits.

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• 4.

### When performing an insulation test on a cable, which test is not commonly performed?

• A.

AC/DC breakdown test

• B.

Doble power factor test

• C.

CT saturation test

• D.

Megger test

C. CT saturation test
Explanation
â€¢ Preform Insulatation resistance (IR)test with a Megaohmeter know as Megger testing
â€¢ Doble is a brand name, power factor test can be used to test the dielectric
â€¢ AC/DC breakdown test can be used to test the insulation however they can be harmful to the insulation in the process, particularly the dc test
â€¢ CT saturation test is for a current transformer (CT) not insulation on a cable

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• 5.

### When performing an insulation resistance test which test is most commonly performed?

• A.

AC/DC breakdown test

• B.

Doble power factor test

• C.

CT saturation test

• D.

Megger test

D. Megger test
Explanation
â€¢ Preform Insulatation resistance (IR)test with a Megaohmeter know as Megger testing
â€¢ Doble is a brand name, power factor test can be used to test the dielectric
â€¢ AC/DC breakdown test can be used to test the insulation however they can be harmful to the insulation in the process, particularly the dc test
â€¢ CT saturation test is for a current transformer (CT) not insulation on a cable

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• 6.

### When performing a power factor test to test the dielectric which test is most commonly performed?

• A.

AC/DC breakdown test

• B.

Doble power factor test

• C.

CT saturation test

• D.

Megger test

B. Doble power factor test
Explanation
â€¢ Preform Insulatation resistance (IR)test with a Megaohmeter know as Megger testing
â€¢ Doble is a brand name, power factor test can be used to test the dielectric
â€¢ AC/DC breakdown test can be used to test the insulation however they can be harmful to the insulation in the process, particularly the dc test
â€¢ CT saturation test is for a current transformer (CT) not insulation on a cable

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• 7.

### Which test can be used to test insulation but can be harmful particularly to dc test?

• A.

AC/DC breakdown test

• B.

Doble power factor test

• C.

CT saturation test

• D.

Megger test

A. AC/DC breakdown test
Explanation
â€¢ Preform Insulatation resistance (IR)test with a Megaohmeter know as Megger testing
â€¢ Doble is a brand name, power factor test can be used to test the dielectric
â€¢ AC/DC breakdown test can be used to test the insulation however they can be harmful to the insulation in the process, particularly the dc test
â€¢ CT saturation test is for a current transformer (CT) not insulation on a cable

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• 8.

### Which vertical run of the following cable needs more support

• A.

Aluminum

• B.

• C.

Copper

• D.

All need the same

C. Copper
Explanation
Copper needs more support compared to the other options because it is denser and heavier than aluminum and aluminum clad copper. Therefore, copper cables are more likely to sag and require additional support to prevent damage or strain on the cable.

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• 9.

### The purpose of dielectric in cable is for

• A.

Reduce void formed during manufacturing

• B.

Increase emissivity

• C.

Increase electric dissipation factor

• D.

Increase breakdown voltage

C. Increase electric dissipation factor
Explanation
So it does not short to ground or another phase
Dissipation factor defined as power to volt-ampres (P/Q) in a circuit. Tangent of Delta

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• 10.

### What type of insulation can not be used on 115KV Cable?

• A.

Paper

• B.

Gas

• C.

Oil

• D.

XLPE

A. Paper
Explanation
Paper insulation cannot be used on 115KV cables because it has a lower dielectric strength compared to other types of insulation. At high voltages, such as 115KV, paper insulation may breakdown and cause electrical failures or short circuits. Therefore, other types of insulation like gas, oil, or XLPE (cross-linked polyethylene) are preferred for higher voltage applications as they provide better insulation properties and can withstand the higher electrical stress.

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• 11.

### Which insulation carries the highest voltage?

• A.

Paper

• B.

Gas

• C.

Oil

• D.

XLPE

D. XLPE
Explanation
The cross-linked polyethylene (XLPE) underground transmission line is often called solid dielectic
cable. The solid dielectric material replaces the pressurized liquid or gas of the pipe-type cables.
XLPE cable has become the national standard for underground electric transmission lines less than
200 kV. There is less maintenance with the solid cable, but impending insulation failures are much
more difficult to monitor and detect. The diameter of the XLPE cables increase with voltage
Each transmission line requires three separate cables, similar to the three conductors required for
aboveground transmission lines. They are not housed together in a pipe, but are set in concrete
ducts or buried side-by-side. Each cable consists of a copper or aluminum conductor and a
semi-conducting shield at its core. A cross-linked polyethylene insulation surrounds the core. The
outer covering of the cable consists of a metallic sheath and a plastic jacket
For 345 kV XLPE construction, two sets of three cables (six cables) are necessary for a number of
reasons, primarily so that the capacity of the underground system matches the capacity of the
overhead line. This design aids in limiting the scope of any cable failure and shortens restoration
time in an emergency situation. Most underground transmission requires increased down time for
the repair of operating problems or maintenance issues compared to overhead lines. The double
sets of cables allows for the rerouting of the power through the backup cable set, reducing the down
time but increases the construction footprint of the line.

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• 12.

### What is the purpose of the semi-conducting material between the conductor and insulation and between the insulation and shield of a synthetic type underground cable?

• A.

Reduce voids forming during manufacturing

• B.

Increase breakdown voltage

• C.

Increase the electric dissipation factor

• D.

Increase emissivity

A. Reduce voids forming during manufacturing
Explanation
Cables may have a layer of semi-conducting material placed around the insulation to act as an electrostatic shield that tend to distribute electrostatic stresses in the insulation.

Emissivity is the measure of the power radiated by a body relative to that radiated by an ideal black body( idealized material which absorbs all incident energy and reflects none) at the same temperature

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• 13.

### In sizing conductors, what is least considered of the following

• A.

Voltage drop

• B.

Heating effect due to conductor proximity, conduit enclosure

• C.

Tripping of circuit breaker protective device

A. Voltage drop
Explanation
NEC code book sizes conductors based on heating effect of mutilple current carrying conductors in a conduit, as well as temperature, and voltage, table 310.13, 310.16.

Conductors size should consider circuit breaker rating since smaller of the two will be the limiting factor.

â€¢ Allowable ampacity, as listed in Table 310.16.
â€¢ Ambient temperature correction factors, if the ambient temperature is not 86Â°F.
â€¢ Conductor ampacity adjustment factors, if four or more current-carrying conductors are bundled together.

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• 14.

### What will limit utilizing the full capacity of conductor

• A.

Series reactance

• B.

Shunt capacitance

• C.

Line losses

• D.

Voltage drop

A. Series reactance
Explanation
Series reactance refers to the opposition to the flow of alternating current caused by the inductance of the conductor. It is a property that limits the flow of current and can reduce the capacity of the conductor to carry the maximum current. Therefore, series reactance can limit the utilization of the full capacity of the conductor.

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• 15.

### The greatest effect of a fault on a system is on

• A.

Transient

• B.

Subtransient

• C.

B. Subtransient
• 16.

### Equal area criterion for power stability for initial fault clearing is

• A.

Power versus power angle

• B.

Time versus System Angle

A. Power versus power angle
Explanation
The equal area criterion for power stability for initial fault clearing states that the power versus power angle graph is used to determine the stability of a power system after a fault occurs. This criterion analyzes the area under the curve of the power-angle graph before and after the fault to assess if the system will remain stable or not. By comparing the areas, it can be determined if the system will oscillate and eventually stabilize or if it will continue to oscillate and become unstable.

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• 17.

### Emissivity is the measure of the power radiated by a body relative to that radiated by an ideal black body( idealized material which absorbs all incident energy and reflects none)  at the same temperature

• A.

True

• B.

False

A. True
Explanation
Emissivity is indeed the measure of the power radiated by a body relative to that radiated by an ideal black body at the same temperature. It is a dimensionless quantity that ranges from 0 to 1, where 0 indicates a perfect reflector and 1 indicates a perfect emitter. The emissivity of a material determines how effectively it can radiate heat energy.

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• 18.

### The absorptivity of a material is affected primarily by its

• A.

Surface

• B.

Elasticity

• C.

Enthalpy

• D.

Divisity

A. Surface
Explanation
The absorptivity of a material is primarily affected by its surface. The surface properties of a material, such as its roughness or smoothness, can determine how efficiently it can absorb or reflect light or other forms of radiation. A rough surface tends to have higher absorptivity as it allows for more interactions between the material and the incident radiation, while a smooth surface may reflect a larger portion of the radiation. Elasticity, enthalpy, and divisity do not directly affect the absorptivity of a material.

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• 19.

### What is the effect of adding a series capacitance to long HV 500KV transmission line:

• A.

Increase angle between the sending end voltage and receiving end voltage

• B.

Line becomes electrically longer

• C.

Offset line inductance for maximum power transfer

• D.

C. Offset line inductance for maximum power transfer
Explanation
Transmission compensation reduces the series impedance of the line (electrically shorter), which is the principal cause of voltage drop and the most important factor in the determining the maximum power which the line can transmit.

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• 20.

### Bus Bar design using Copper over aluminum because

• A.

Aluminum has higher surface emissivity

• B.

Copper is more corrosive

• C.

Copper has higher thermal coefficient

• D.

Copper has lower thermal coefficient

D. Copper has lower thermal coefficient
Explanation
Copper has a lower thermal coefficient compared to aluminum, which means that it is a better conductor of heat. This makes copper a more suitable choice for bus bar design as it will be able to efficiently dissipate heat generated during operation. On the other hand, aluminum has a higher surface emissivity, meaning it can radiate heat more easily. However, this is not as important in bus bar design as the ability to conduct heat effectively. The statement about copper being more corrosive is incorrect, as aluminum is actually more prone to corrosion.

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• 21.

### Which of the following changes would make the least difference in the resistance of a ground rod installation?

• A.

Increasing the spacing from 1 to 3 ft

• B.

Doubling the number of ground rods

• C.

Doubling the diameter of the ground rods

• D.

Increasing the depth of the rods from 4 to 6 feets

C. Doubling the diameter of the ground rods
Explanation
Doubling the diameter of the ground rods would make the least difference in the resistance of a ground rod installation. This is because the resistance of a ground rod installation is inversely proportional to the diameter of the rods. Doubling the diameter would decrease the resistance, making it the change that would make the least difference. Increasing the spacing, doubling the number of ground rods, and increasing the depth of the rods would all have a greater impact on the resistance of the installation.

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• 22.

### The most important function of the shield on underground cable operated at 2KV or above is to provide

• A.

A moisture barrier for the cable insulation

• B.

Conductance needed for the charging current

• C.

A tangential pattern of electrical stresses

• D.

A radial pattern of electrical stresses

D. A radial pattern of electrical stresses
Explanation
The shield on underground cable operated at 2KV or above provides a radial pattern of electrical stresses. This means that the shield is designed to distribute the electrical stresses evenly across the insulation of the cable, reducing the concentration of stress at any particular point. This helps to prevent electrical breakdown and ensures the insulation remains intact. The shield also provides other functions such as conducting the charging current, but its most important function is the radial distribution of electrical stresses.

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• 23.

### Which cable insulation carries the highest voltage

• A.

Paper

• B.

Gas

• C.

Oil

• D.

Silicon

C. Oil
Explanation
Oil is the correct answer because it is commonly used as an insulating material in high voltage cables. It has excellent dielectric properties, allowing it to withstand high voltages without breaking down. Oil insulation also provides good heat dissipation, which is important in high voltage applications. Additionally, oil is resistant to moisture and contaminants, ensuring the longevity and reliability of the cable insulation.

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• 24.

### What is not an insulation test?

• A.

AC/DC breakdown test

• B.

Double dower factor

• C.

CT saturation test

• D.

Megger test

C. CT saturation test
Explanation
The CT saturation test is not an insulation test. Insulation tests are performed to determine the integrity of the insulation material used in electrical equipment, while the CT saturation test is conducted to check the performance and accuracy of current transformers (CTs). It involves applying a high current to the CT and measuring the output to ensure that it is within the desired range. Therefore, the CT saturation test does not directly relate to insulation testing and is not considered as an insulation test.

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• 25.

### DC Hipot test of equipment is:

• A.

Diaelctric Test

• B.

Pass/Fail

• C.

Non-destructive

• D.

Diaelctric Test and Pass/Fail

• E.

Diaelctric Test and Non-destructive

• F.

Destructive

• G.

Diaelctric Test and Pass/Fail and Destructive

G. Diaelctric Test and Pass/Fail and Destructive
Explanation
The correct answer is "Diaelctric Test and Pass/Fail and Destructive". This means that the DC Hipot test of equipment involves conducting a dielectric test to measure the insulation strength, determining if the equipment passes or fails based on the test results, and potentially causing damage or destruction to the equipment during the testing process.

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• 26.

### What type of connector can be used to connect to a tin plated bronzed alloyed?

• A.

Aluminum only

• B.

Cooper only

• C.

Bronzed tinned alloyed only

• D.

Either copper or aluminum

D. Either copper or aluminum
Explanation
Either copper or aluminum can be used as a connector to connect to a tin plated bronzed alloyed. Copper and aluminum are both commonly used as conductive materials in electrical connections. They have good conductivity properties and can effectively transfer electrical signals or power. Therefore, either copper or aluminum can be suitable choices for connecting to a tin plated bronzed alloyed material.

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• 27.

### When testing an energized line with a device, you test it by:

• A.

Zeroing the device before and after the test

• B.

Checking with a lower rated device

• C.

Checking with a higher rated device

• D.

Using the device to check an energized line with known values

D. Using the device to check an energized line with known values
Explanation
When testing an energized line with a device, the correct approach is to use the device to check an energized line with known values. This means that the device is used to measure the electrical parameters of the line, such as voltage or current, which are already known. By comparing the measured values with the known values, the accuracy and functionality of the device can be verified. This method ensures that the device is working properly and provides reliable results.

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• 28.

### What would be chosen at DWP in terms of telemetering and why?

• A.

Analog circuits because theya are faster and more reliable

• B.

Analog circuits because they are slower but more reliable

• C.

Digital circuits because they are faster and more reliable

• D.

Digital circuits because they are slower but more reliable

C. Digital circuits because they are faster and more reliable
Explanation
Digital circuits are chosen at DWP in terms of telemetering because they are faster and more reliable compared to analog circuits. Digital circuits have the advantage of faster data transmission and processing speeds, allowing for real-time monitoring and control. They also offer better reliability as they are less susceptible to noise and interference. Additionally, digital circuits provide the ability to easily store and analyze data, enabling more efficient troubleshooting and maintenance.

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• 29.

### At voltage levels of 100 KV or higher which element is commonly used due to cost consideration for measurement of a power system

• A.

Current Transformers (CTs)

• B.

Voltage Transformers (PTs)

• C.

Coupling Capacitance Voltage Transformers (CCVTs)

• D.

Variable Coupling Capacitors

A. Current Transformers (CTs)
Explanation
At voltage levels of 100 KV or higher, Current Transformers (CTs) are commonly used due to cost considerations for measurement of a power system. CTs are more cost-effective compared to Voltage Transformers (PTs) and Coupling Capacitance Voltage Transformers (CCVTs) at these higher voltage levels. Variable Coupling Capacitors are not commonly used for measurement of a power system at these voltage levels.

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• 30.

### Which device has the lowest accuracy when measuring power system for a fault?

• A.

Current Transformers (CTs)

• B.

Voltage Transformers (PTs)

• C.

Coupling Capacitance Voltage Transformers (CCVTs)

• D.

Variable Coupling Capacitors

C. Coupling Capacitance Voltage Transformers (CCVTs)
Explanation
CCVTs have the lowest accuracy when measuring power system for a fault. This is because CCVTs are primarily used for voltage measurement and not designed for high accuracy fault measurement. Current Transformers (CTs) and Voltage Transformers (PTs) are specifically designed for fault measurement and have higher accuracy. Variable Coupling Capacitors are not commonly used for fault measurement and therefore their accuracy is not relevant in this context.

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• 31.

### The positive negative and zero sequence of a solidly grounded system under steady state conditions always follow the relations:

• A.

Z1 > Z2 >Z0

• B.

Z1 < Z2

• C.

Z0 < Z1 < Z2

• D.

None

D. None
Explanation
The given relations Z1 > Z2 > Z0, Z1 < Z2, and Z0 < Z1 < Z2 contradict each other. Therefore, none of the given relations are correct.

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• 32.

### Capacitor switching is easily done with:

• A.

Air blast circuit breaker

• B.

Oil C.B.

• C.

Vaccum C.B.

• D.

Any of the above

C. Vaccum C.B.
Explanation
Capacitor switching is easily done with a Vacuum Circuit Breaker (Vaccum C.B.) because it has the capability to handle the high inrush current that occurs during the switching process. Vacuum circuit breakers are specifically designed to interrupt high voltage and high current circuits, making them suitable for capacitor switching applications. They provide reliable and efficient switching operations, ensuring the protection of the capacitor and the overall electrical system. Air blast circuit breakers and oil circuit breakers may not be as suitable for capacitor switching due to their limitations in handling high inrush currents.

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• 33.

### For measuring positive, negative and zero sequence voltages in a system, the reference is taken as:

• A.

Neutral of the system only

• B.

Grounds only

• C.

For zero sequence the neutral and for positive and negative the ground

• D.

The base values of the system in either ohmic or per unit values (p.u. or %)

D. The base values of the system in either ohmic or per unit values (p.u. or %)
Explanation
If we look at any electrical power system, we will find, these are several voltage levels. For example, suppose a typical power system where electrical power is generated at 6.6 kV then that 132 kV power is transmitted to terminal substation where it is stepped down to 33 kV and 11 kV levels and this 11 kV level may further step down to 0.4kv. Hence from this example it is clear that a same power system network may have different voltage levels. So calculation of fault at any location of the said system becomes much difficult and complicated it try to calculate impedance of different parts of the system according to their voltage level. This difficulty can be avoided if we calculate impedance of different part of the system in reference to a single base value. This technique is called impedance notation of power system. In other wards, before electrical fault calculation, the system parameters, must be referred to base quantities and represented as uniform system of impedance in either ohmic, percentage, or per unit values.
Electrical power and voltage are generally taken as base quantities. In three phase system, three phase power in MVA or KVA is taken as base power and line to line voltage in KV is taken as base voltage.
http://www.electrical4u.com/electrical-fault-calculation-positive-negative-zero-sequence-impedance/

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• 34.

### A fault line is more severe from the point of RRRV method if it is a:

• A.

Short line fault

• B.

Medium line fault

• C.

Long line fault

• D.

None of the above

A. Short line fault
Explanation
The RRRV method stands for Relative Rupture Risk Value, which is a measure of the potential severity of a fault line. In this context, a short line fault refers to a fault line that is shorter in length. The RRRV method considers shorter fault lines to be more severe because they tend to have higher rupture rates and can cause more significant damage. Therefore, a short line fault would be considered more severe from the point of view of the RRRV method.

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• 35.

### High voltage DC testing for HV machines is needed because:

• A.

Certain conclusions ca be drawn regarding the continuous ageing of an insulation.

• B.

The stress distribution is a representation of the service condition

• C.

Standardization on the magnitude of voltage to be applied is available

• D.

The stress do not damage the coil insulation

A. Certain conclusions ca be drawn regarding the continuous ageing of an insulation.
Explanation
High voltage DC testing for HV machines is needed because it allows us to draw certain conclusions regarding the continuous aging of an insulation. This testing helps to assess the condition of the insulation and determine if it is deteriorating over time. By subjecting the insulation to high voltage DC, any weaknesses or defects in the insulation can be identified, which can help in predicting and preventing potential failures in the future. This testing method provides valuable information about the insulation's performance and helps in making informed decisions about maintenance and replacement.

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• 36.

### A voltage controlled bus is treated as a load bus in subsequent iterations when its:

• A.

Voltage limit is violated

• B.

Active power limit is violated

• C.

Reactive power limit is violated

• D.

Phase angle limit is violated

C. Reactive power limit is violated
Explanation
This should be categorized as transmission or power flow.

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• 37.

### Sheaths are used in cables to

• A.

Provide proper insulation

• B.

Provide mechanical strength

• C.

Prevent ingress of moisture

• D.

None

B. Provide mechanical strength
Explanation
Sheaths are used in cables to provide mechanical strength. This is because the sheath acts as a protective layer around the inner components of the cable, preventing them from being damaged or broken. The sheath helps to support and reinforce the cable, making it more resistant to external forces such as tension, compression, and bending. By providing mechanical strength, the sheath ensures that the cable can withstand the physical stresses it may encounter during installation, handling, and operation.

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• 38.

### Corona loss is less when the shape of the conductor is

• A.

Circular

• B.

Flat

• C.

Oval

• D.

Corona loss is independent of shape

A. Circular
Explanation
The correct answer is Circular because the shape of the conductor plays a significant role in determining the corona loss. Circular conductors have a smaller surface area compared to other shapes, which reduces the electric field intensity and minimizes the corona discharge. This results in lower corona loss.

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• 39.

### If & is the loss angle of the cable, its power factor is:

• A.

Sin &

• B.

Cos &

• C.

Power factor is independent of &

• D.

None

A. Sin &
Explanation
The power factor of a cable is determined by its loss angle, which is represented by the symbol &. The loss angle is related to the sine of &. Therefore, the correct answer is "Sin &".

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• 40.

### The order of lightning discharge current is

• A.

10,000 amp

• B.

100

• C.

1amp

• D.

1 micro amp

A. 10,000 amp
Explanation
The order of lightning discharge current is 10,000 amp. This means that the magnitude of the current during a lightning discharge is approximately 10,000 amperes. Lightning is a powerful natural phenomenon that involves the rapid flow of electric charge through the atmosphere. The high current is a result of the huge amount of energy released during a lightning strike.

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