Discussion Overview
The discussion revolves around the realistic breakdown values for electric fields in air and the influence of materials like FR4 on these values. Participants explore the variability of breakdown voltage under different conditions, including temperature, pressure, and humidity, as well as the implications for high voltage applications.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants note that textbooks state the breakdown value for the electric field in air is 3*10^6 V/m, while other sources suggest it can be as low as 1*10^6 V/m.
- There is a proposal that the breakdown voltage increases in the presence of a dielectric like FR4, with a reference to the equation V=ε E*d, where ε is the dielectric constant.
- One participant mentions that the breakdown voltage varies with pressure, referencing the Paschen Curve as a relevant source.
- Another participant raises the question of whether the equation V=ε E*d is valid under standard temperature and pressure conditions.
- Humidity is identified as another factor that affects breakdown voltage, with some participants suggesting that it is particularly relevant when considering constant humidity conditions.
- A reference is made to the book "Reference Data for Radio Engineers," which contains graphs for breakdown voltage and discusses how breakdown voltage varies with spacing, pressure, temperature, and the geometry of electrodes.
- One participant expresses a need for breakdown information for compliance with UL standards, indicating that there is some uncertainty and complexity in calculating breakdown voltage even under standard conditions.
Areas of Agreement / Disagreement
Participants express varying views on the breakdown values and the factors influencing them, indicating that there is no consensus on a single value or approach. The discussion remains unresolved regarding the validity of the equation V=ε E*d under different conditions.
Contextual Notes
Participants highlight limitations such as the dependence of breakdown voltage on environmental factors like humidity, pressure, and temperature, as well as the geometry of the electrodes, which complicates the discussion.