Can Different Electrodes Affect Air's Dielectric Strength Values?

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Discussion Overview

The discussion centers on the dielectric strength of air and whether it can vary based on the type of electrodes used in testing. Participants explore the relationship between electrode configuration and breakdown voltage, considering factors such as pressure and temperature.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant suggests that dielectric strength is a property of the material (air) and should have a single value.
  • Another participant agrees but notes that dielectric strength can also depend on external conditions like pressure and temperature.
  • It is proposed that different electrode types create varying electric field distributions, which could lead to different breakdown voltages even under the same environmental conditions.
  • A later reply confirms that differences in breakdown voltages observed with different electrodes are likely due to the differing electric field configurations.

Areas of Agreement / Disagreement

Participants generally agree that dielectric strength is influenced by the type of electrodes used, but there is no consensus on whether this variability undermines the idea of a single value for air's dielectric strength.

Contextual Notes

The discussion does not resolve the implications of varying dielectric strength values in relation to the definition of dielectric strength as a material property.

Physicist3
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Hi,

Am I correct in thinking that for a medium such as air, the dielectric strength is a property of the material and as such has a single value for that material? The reason I ask is because I have been testing the breakdown of air between different types of electrodes and because the breakdown is different for different electrode heads, I will end up with multiple values of dielectric strength (kV/mm). Is this possible?
 
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Physicist3 said:
Hi,

Am I correct in thinking that for a medium such as air, the dielectric strength is a property of the material and as such has a single value for that material? The reason I ask is because I have been testing the breakdown of air between different types of electrodes and because the breakdown is different for different electrode heads, I will end up with multiple values of dielectric strength (kV/mm). Is this possible?
  1. Yes, but even for uniform E-fields it is also a function of pressure and temperature.
  2. Yes, it is possible becouse for different types of electrode heads the field configuration in the gap isn't same
 
So if all three electrode types were tested in the same location (same pressure and temp), the difference in breakdown voltages observed would be because of the distribution of the electric field which differs with each electrode type?
 
Yup
 

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