MCQs

As compared to winter, the sag of transmission lines in summer is: More Less Same Correct answer: 1. More

The sag in transmission lines depends on which factor: Length of transmission lines Temperature of surrounding Weight of conductors All of these Correct answer: 4. All of these

The factor having least effect on sag of transmission lines: Weight of conductor Current passing through conductor Ice fall Atmospheric temperature Correct answer: 2. Current passing through conductor

The required dry flashover voltage for porcelain is about how many times the rated voltage: 1 – 1.5 times 1.5 – 2 times 2.5 – 3 times 30 times Correct answer: 3. 2.5 – 3 times

The minimum insulation requirement of a 500 kV line is: 139 kV 228 kV 317 kV 692 kV Correct answer: 3. 317 kV From formula: 500  kV * 1.1 / 1.732 = 317 kV

The correct statement about conductivity of aluminum as compared to copper: Aluminum has high conductivity Copper has high conductivity Both have same conductivity None of these Correct answer: 2. Copper has high conductivity

Larger cross-arms are required in case of which conductor: Aluminum Copper Both required same Correct answer: 1. Aluminum Explanation: Since the Aluminum conductor is light as compared to the copper conductor, it is liable to greater swings and thus required larger cross arms.

The specific gravity of Aluminum as compared to copper is: Lower Higher Same Correct answer: 1. Lower Explanation: The specific gravity of aluminum is 2·71 gm/cc which is lower than copper. Copper has specific gravity of 8·9 gm/cc