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The correct answer is option  2): HVDC transmission

Concept:

• In HVDC, cost of transmission is less, since only two conductors are used for transmission.
• There is no reactive power. So transmission losses are reduced. Due to high voltage transmission, for the same power current is less.
• So I²R loss is very less.
• Hence for bulk power transmission over very long distance HVDC transmission preferably used.

Additional InformationAdvantages of HVDC transmission:

No Skin Effect:

In HVDC transmission current distributes uniformly over the cross-section of the conductor. Hence no loss due to skin effect is encountered.

For the same current-carrying capacity HVDC lines have lesser cross-section compared to HVAC lines

Lower Transmission Losses:

HVDC transmission requires only two conductors. Therefore the power loss in the DC line will be lesser compared to the AC line

Good voltage Regulation:

In DC lines, a voltage drop does not exist due to inductive reactance. Voltage Regulation will be better in HVDC transmission

Surge Impedance Loading:

Long EHV lines are loaded to less than 80% of the natural load. No such condition is applicable in HVDC transmission

No Line Loading Limit:

The permissible loading limit on EHV AC lines is limited by the transient stability limit and the line reactance to almost one-third of the thermal rating of the conductors.

No such limitations exist in the case of HVDC line

Lesser Corona Loss and Radio Interference: Corona Loss directly proportional to frequency. Therefore in the DC line, corona loss will be lesser compared to the AC line.

The correct answer is option 1): ampere-hour

Concept:

• The capacity of a battery is shown as ampere-hour
• 1 ampere of current flowing for one hour.
• During the hour, the amount of charge transferred in is 3,600 coulombs (ampere-seconds).
• For example, a 12V lithium battery with a capacity of 100Ah can deliver 100A to a 12-volt device for one hour.
• The same 100Ah battery could supply power for 4 hours (100/25=4) to a 25-ampere device.

The correct answer is option 4

The neutral wire is marked with Black color

Concept:

Additional Information

Ground wire:

• It is a wire that provides an alternate path for the excess charge.
• The excess charge goes to the ground, as the ground acts as zero potential surfaces.
• It protects us from electrical shock.
• It protects appliances from electrical fires

Among the following options, RCT has the bidirectional current capability.

RCT

• The full form of RCT is reverse conducting thyristor.
• It consists of an SCR and a diode connected anti-parallel, hence current flows in both directions.
• Because of the reverse diode, this thyristor is not capable of reverse blocking. These devices are advantageous where a reverse or freewheel diode must be used.

The DC-type capacitor is an aluminum electrolytic capacitor.

Aluminum electrolytic capacitor:

• Aluminum electrolytic capacitors are polarized electrolytic capacitors whose anode electrode (+) is made of pure aluminum foil with an etched surface.
• The aluminum forms a very thin insulating layer of aluminum oxide by anodization that acts as the dielectric of the capacitor.
• A non-solid electrolyte covers the rough surface of the oxide layer, serving in principle as the second electrode (cathode) (-) of the capacitor.
• A second aluminum foil called “cathode foil” contacts the electrolyte and serves as the electrical connection to the negative terminal of the capacitor.
• They are made with capacitance values from 0.1 µF up to 2.7 Fand rated voltage values from 4 V up to 630 V.

Magnetic susceptibility is a dimensionless proportionality constant that indicates the degree of magnetization of a material in response to an applied magnetic field. 

The relation between magnetic susceptibility and temperature is:

\(ζ={C\over T-T_c}\)

where, ζ = Magnetic susceptibility

C = Curie constant

T_c = Curie temperature

Explanation:

From the above expression, ζ α 1/T

The magnetic susceptibility decreases with an increase in temperature. So, ferromagnetism decreases with rising temperature.

It is maximum at absolute zero temperature and becomes zero at curie temperature.

Above this temperature, the ferromagnetic material becomes paramagnetic.

The correct answer is option 2):(Magnetisation / Magnetising force)

Concept:

• Magnetic susceptibility is a measure of how much a material will become magnetized in an applied magnetic field.
• It is a scalar quantity with no units and dimensions The magnetic susceptibility indicates whether a material is repelled out or attracted to a magnetic field.
• The diamagnetic substance is those which repel the magnetic field and henceforth their susceptibility is negative. It is positive for paramagnetic material and ferromagnetic material has large positive magnetic susceptibility.
• Magnetic susceptibility (X) of a material is the ratio of magnetization I (magnetic moment per unit volume) to the applied magnetizing field intensity H.
• X = \(Magnetisation \over Magnetising:force\)

The correct answer is option 4):  (60 cm × 60 cm × 6.35 mm)

Concept:

• In areas with high soil resistivity, GI (Galvanized Iron) Earthing Electrodes give a low-impedance ground.
• This method dissipates lightning surges and other dangerous electrical fault currents
• When it is used in conjunction with Reflow Grounding Minerals, it will work well even in  sandy or rocky soil conditions
• A GI plate of minimum size 600mm x600mm and thickness of 6.3 mm is used.
• Where in the case of a copper (plate) a minimum thickness of 3.15mm can be used.
• The plate is placed such that the earthing plate is surrounded by an alternate layer of charcoal and salt.

The correct answer is option 3):Copper

Concept:

Insulation is a nonconductive material within a cable's construction

The principal insulating materials used in cables are

• Rubber,
• Vulcanized India rubber, i
• Impregnated paper,
• Varnished cambric
• Polyvinyl chloride.

Copper is the conductor. it should not used for insulation purposes

The correct answer is option 4):(113.64 A)

Concept:

The current rating of the transformer is given as

Current = \(KVA \over V\)

KVA is  KVA Rating

V is the Voltage

Calculation:

KVA =  25 × 10³ VA

Secondary voltage = 220 V

Secondary current = \(25 × 10^3\over 220\)

=113.6363 A