POWER SYSTEM (TRANSMISSION AND DISTRIBUTION)

Which of the following is usually not the generating voltage?

• 11 kV

• 13.2 kV

• 9.9 kV

• 6.6 kV

The fact that a conductor carries more current on the surface as compared to core is known as

• corona

• permeability

• unsymmetrical fault

• skin effect

Transmission efficiency increases as

• voltage and power factor both decrease

• voltage and power factor both increase

• voltage increases but power factor decreases

• voltage decreases but power factor increases

Skin effect is proportional to

• (diameter of conductor)^2

• (diameter of conductor)^3

• diameter of conductor

• (diameter of conductor)^1/2

The surge impedance for overhead line is taken as

• 50-60 ohms

• 10-20 ohms

• 1000-2000 ohms

• 100-200 ohms

The effect of corona is

• increased reactance

• increased energy loss

• increased inductance

• all of the above

The current drawn by the line due to corona losses is

• square

• non-sinusoidal

• sinusoidal

• triangular

Presence of ozone as a result of corona is harmful because

• it gives bad odor

• reduces the power factor

• it transfers energy to the ground

• it corrodes the material

For 33 kV lines, the number of insulator discs used is

• 8

• 12

• 5

• 3

For 11 kV lines, the number of insulator discs used is

• 1

• 12

• 5

• 3