Question

Assuming that the breakdown voltage of a non-uniform field spark gap in atmospheric air of humidity 11g/m³ is given by the expression Vs = Apd + B√pd where ‘d' is the gap length in cm, rho is the relative air density and A and B are constants, complete the following table

Gap length (cm) Humidity (g/m³) Pressure (mb) Temp (°C) Breakdown(kV)
2.0 7 533 5 33.48
1.25 3 933 25 34.46
1.5 11 500 47 ?
Assume that, over the range of humidity in question, a correction factor of +0.2% per g/m³ increase in humidity can be applied to the spark over voltage irrespective of density

Answer 1

The breakdown voltage for a non-uniform field spark gap can be calculated using given variables and by applying a humidity correction factor. The breakdown field strength of air is approximately 3.0×106 V/m, which limits the voltage between conductors to prevent discharge.

Step-by-step explanation:

The student is asking how to determine the breakdown voltage for a non-uniform field spark gap at a certain humidity, pressure, and temperature. Using the given variables A, B, rho (relative air density), and d (gap length), and the humidity correction factor, we can calculate the breakdown voltage.

According to the provided formulas and information, humid air allows for a lower breakdown voltage, meaning a spark can jump through humid air at a lower voltage compared to dry air. Moreover, air breaks down at about 3.0×106 V/m, which limits the amount of voltage that can be applied between conductors before a discharge occurs.