High Voltage Engineering MCQs
 The relative dielectric strength of SF6 as compared to air is:
 1.5 times
 2 times
 2.5 times
 3 times
Ans: 3
2. The correct statement about Paschen’s law states that breakdown voltage of a uniform gap is directly proportional to:

 Pressure of the gas
 Separation of electrode
 Material of electrode
 All of these
 1 & 3
Ans: 4
3. For determining intrinsic strength of dielectric the applied voltage should be of the order of:

 10^{8} sec
 10^{16} sec
 10^{24} sec
 10^{32} sec
Ans: 1
4. The ratio of voltage drop in a 6 stage to 3 stage Cockroft Walton circuit is:

 6
 2
 9
 1
5. Sometimes a void appears in the dielectric, the correct statement regarding the void is that its:


 Electric field strength is lower than that of the dielectric
 Electric field strength is higher than that of the dielectric
 Electric field strength is exactly similar to the dielectric

Ans: 2
6. The onset voltage for Trichel pulses:

 Increases exponentially with increase in gap length
 Increases exponentially with decrease in gap length
 Increases directly with increase in gap length
 Is independent of gap length
Ans: 4
7. The frequency response of Rogowski coil is flat upto:

 100 MHz
 200 MHz
 500 MHz
 1000 MHz
Ans: 1
8. The small load current in Cockroft – Walton circuit means:

 Voltage drop is very large
 Voltage drop is small
 None of these
 Can’t predict
Ans: 2
9. The dielectric strength of liquids is of the order:

 100 kV/cm
 1000 kV/cm
 5000 kV/cm
 10000 kV/cm
Ans: 1
10. Temperature limit for Class H insulation is:

 90°C
 180°C
 200°C
 400°C
Ans: 2