Power System MCQs Part 9

Power System MCQs Part 9

For reducing tower footing resistance it is better to employ

For reducing tower footing resistance it is better to employ

1. Chemical and ground rods only
2. Ground rod and counterpoise only
3. Chemical and counterpoise only
4. Chemical, ground rods and counterpoise

Correct answer: 2. Ground rod and counterpoise only

The size of conductor on modern EHV lines is obtained based on

The size of conductor on modern EHV lines is obtained based on:

1. Voltage drop
2. Current density
3. Corona
4. None of these

Correct answer: 3. Corona

Which of following is correct regarding a short length of cable between the dead end tower and the power transformer

Which of following is correct regarding a short length of cable between the dead end tower and the power transformer

1. It reduces the steepness of the wave under certain conditions only
2. It does not change the steepness
3. It always reduces the steepness of the incident wave

Correct answer: 3. It always reduces the steepness of the incident wave

Minimum oil circuit breaker has less volume of oil because

Minimum oil circuit breaker has less volume of oil because

1. There is insulation between contacts
2. Solid insulation is provided for insulating the contacts from earth
3. The oil between the breaker contacts has greater strength
4. None of these

Correct answer: 2. Solid insulation is provided for insulating the contacts from the earth

If r is the radius of the conductor and R the radius of the sheath of the cable, the cable operates stably from the view point of dielectric strength if

If r is the radius of the conductor and R the radius of the sheath of the cable, the cable operates stably from the view point of dielectric strength if:

1. r/R > 1.0
2. r/R < 1.0
3. r/R < 0.368
4. r/R < 0.667

Correct answer: 3. r/R < 0.368