# High Voltage Engineering MCQs Part 3

1. The relative dielectric strength of SF6 as compared to air is:
1. 1.5 times
2. 2 times
3. 2.5 times
4. 3 times
2. The correct statement about Paschen’s law states that breakdown voltage of a uniform gap is directly proportional to:
1. Pressure of the gas
2. Separation of electrode
3. Material of electrode
4. All of these
5. 1 & 3
• Correct answer: 4. All of these
3. For determining intrinsic strength of dielectric the applied voltage should be of the order of:
1. 10-8 sec
2. 10-16 sec
3. 10-24 sec
4. 10-32 sec
• Correct answer: 1. 10-8 sec
4. The ratio of voltage drop in a 6 stage to 3 stage Cockroft Walton circuit is:
1. 6
2. 2
3. 9
4. 1
5. Sometimes a void appears in the dielectric, the correct statement regarding the void is that its:
1. Electric field strength is lower than that of the dielectric
2. Electric field strength is higher than that of the dielectric
3. Electric field strength is exactly similar to the dielectric
• Correct answer: 2. Electric field strength is lower than that of the dielectric
6. The onset voltage for Trichel pulses:
1. Increases exponentially with increase in gap length
2. Increases exponentially with decrease in gap length
3. Increases directly with increase in gap length
4. Is independent of gap length
• Correct answer: 4. Is independent of gap length
7. The frequency response of Rogowski coil is flat upto:
1. 100 MHz
2. 200 MHz
3. 500 MHz
4. 1000 MHz
• Current answer: 1. 100 MHz
8. The small load current in Cockroft – Walton circuit means:
1. Voltage drop is very large
2. Voltage drop is small
3. None of these
4. Can’t predict
• Current answer: 2. Voltage drop is small
9. The dielectric strength of liquids is of the order:
1. 100 kV/cm
2. 1000 kV/cm
3. 5000 kV/cm
4. 10000 kV/cm
• Current answer: 1. 100 kV/cm
10. Temperature limit for Class H insulation is:
1. 90°C
2. 180°C
3. 200°C
4. 400°C