Question 1

As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only
A)31.25 percent of copper
B)33.3 percent of copper
C)66.7 percent of copper
D)125 percent of copper

Accepted Answer

A 3-wire DC distributor system, when compared to a 2-wire system with the same maximum voltage to earth, uses only 31.25% of the copper. This is because in a 3-wire system, the total copper required is proportional to the square of the system voltage, and by effectively doubling the voltage (using a midpoint earthed), the copper requirement is significantly reduced.

Question 2

Which of the following is usually not the generating voltage ?
A)6.6 kV
B)8.8 kV
C)11 kV
D)13.2 kV

Accepted Answer

8.8 kV is not a standard generating voltage. Standard generating voltages are typically 6.6 kV, 11 kV, and 13.2 kV, among others, due to their widespread acceptance and use in electrical systems and equipment.

Question 3

For an overhead line, the surge impedance is taken as
A)20-30 ohms
B)70-80 ohms
C)100-200 ohms
D)500-1000 ohms

Accepted Answer

The surge impedance of an overhead line typically falls within the range of 100-200 ohms due to the line's inductance and capacitance characteristics.

Question 4

The presence of ozone due to corona is harmful because it
A)reduces power factor
B)corrodes the material
C)gives odour
D)transfer energy to the ground

Accepted Answer

Ozone is a reactive gas that can corrode materials, especially metals and rubber, leading to damage and degradation.

Quiz 2: Electrical Supply and Distribution

As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only

Which of the following is usually not the generating voltage ?

For an overhead line, the surge impedance is taken as

The presence of ozone due to corona is harmful because it