Peek's law

In physics, Peek's law is a description of the conditions necessary for corona discharge between two wires:

:$e\_v\; =\; m\_v\; g\_v\; delta\; r\; ln\; left\; (\{S\; over\; r\}\; ight\; )$

"e"_v is the "visual critical corona voltage" or "corona inception voltage" (CIV), the voltage (in kilovolts) required to initiate a visible corona discharge between the wires.

"m"_v is an irregularity factor to account for the condition of the wires. For smooth, polished wires, "m"_v = 1. For roughened, dirty or weathered wires, 0.98 to 0.93, and for cables, 0.87 to 0.83.

"r" is the radius of the wires

"S" is the distance between the wires

δ is the air density factor. It is calculated by the equation:::$delta\; =\; \{3.92\; b\; over\; 273\; +\; t\}$:where :* "b" = pressure in centimeters of mercury:* "t" = temperature in degrees Celsius

:At SATP (25°C and 76 cmHg):

::$delta\; =\; \{3.92cdot76\; over\; 273\; +\; 25\}\; =\; 1$

"g"_v is the "visual critical" potential gradient, and is calculated by the equation:

::$g\_v\; =\; g\_0\; delta\; left\; (\; 1\; +\; \{0.301\; over\; sqrt\{delta\; r\; ight\; )$:where "g"₀ is the "disruptive critical" potential gradient, about 30 kV/cm for air [cite web|last=Hong|first=Alice|title= Electric Field to Produce Spark in Air (Dielectric Breakdown)|work=The Physics Factbook|year=2000|url=http://hypertextbook.com/facts/2000/AliceHong.shtml]

References

*
* [http://print.google.com/print?id=jDn78ePM-nwC High Voltage Engineering Fundamentals] , E.Kuffel and WS Zaengl, Pergamon Press, p366