Electrical Power Transmission MCQs Part 16

Electrical Power Transmission MCQs Part 16

Contents

Potential across the various discs of suspension string is different. This is primarily due to

Potential across the various discs of suspension string is different. This is primarily due to:

1. Self-capacitance
2. Shunt capacitance
3. Both of these
4. None of these

Also see: String efficiency formula

If safety factor is doubled, sag of line will

If safety factor is doubled, sag of line will:

1. Increase
2. Decrease
3. Remain unchanged
4. None of the above

Explanation:

The formula for allowable tension (T) is: T = Ultimate strength/Safety factor

While Sag has the formula: S = (wl²)/8T = {(wl²)/8 } * {Safety Factor/Ultimate strength}

Since both are directly related to each other, doubling safety factor increases sag

Shunt capacitance in string of suspension insulators can be decreased using

Shunt capacitance in string of suspension insulators can be decreased using:

1. Shorter cross-arms
2. Longer cross-arms
3. Longer spans
4. None of these

Explanation: In order to reduce shunt capacitance, distance of conductor from tower must be increased. In other terms/words, the longer cross-arms should be used.

If spacing between conductors increases, the corona effect

If spacing between conductors increases, the corona effect:

1. Increases
2. Decreases
3. Remains unchanged
4. None of these

Explanation: If spacing between conductors is large compared to their diameters, the electrostatic stress at conductor surface is decreases. As a result of this the corona effect decreases.

Power loss in an overhead transmission line mainly occurs due to

Power loss in an overhead transmission line mainly occurs due to:

1. Resistance of the line
2. Capacitance of the line
3. Inductance of the line
4. None of these

Correct answer: 1. Resistance of the line

Explanation: The line resistance is the major factor that is responsible for power loss in an overhead transmission line.

See complete list of Electric Power Transmission MCQs