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In [[physics]], '''Peek's law''' defines the electric potential gap necessary for triggering a [[corona discharge]] between two wires: | |||
<!--:<math>e_v = m_v g_v \delta r \ln \left ({S \over r} \right )</math>--> | |||
::<math>e_v = m_v g_v r \ln \left ({S \over r} \right )</math> | |||
''e''<sub>v</sub> is the "visual critical corona voltage" or "corona inception voltage" (CIV), the voltage <!--(in kilovolts) {unit is a nonsense if you do not provide an actual numerical quantity or the unit of the rest of the quatities} --> required to initiate a visible corona discharge between the wires. | |||
''m''<sub>v</sub> is an irregularity factor to account for the condition of the wires. For smooth, polished wires, ''m''<sub>v</sub> = 1. For roughened, dirty or weathered wires, 0.98 to 0.93, and for [[cable]]s, 0.87 to 0.83, namely the surface irregularities result in diminishing the corona threshold voltage. | |||
''r'' is the [[radius]] of the wires in cm. | |||
''S'' is the distance between the wires | |||
δ is the air density factor <!--It is calculated by the equation: | |||
::<math>\delta = {3.92 b \over 273 + t}</math> | |||
:where | |||
:* ''b'' = pressure in centimeters of mercury | |||
:* ''t'' = temperature in degrees Celsius | |||
:At -->with respect to [[Standard conditions for temperature and pressure|SATP]] (25°C and 76 [[cmHg]]): | |||
<!--::<math>\delta = {3.92\cdot76 \over 273 + 25} = 1</math>--> | |||
::<math>\delta = {\rho \over \rho_{SATP}}</math> | |||
''g''<sub>v</sub> is the "visual critical" [[electric field]], and is calculated by the equation: | |||
<!--::<math>g_v = g_0 \delta \left ( 1 + {0.301 \over \sqrt{\delta r}} \right )</math>--> | |||
::<math>g_v = g_0 \delta \left ( 1 + {c \over \sqrt{\delta r}} \right )</math> | |||
:where ''g''<sub>0</sub> is the "disruptive electric field", and c is an empirical dimensional constant. The values for those parameters are usually considered to be about 30-32 [[kilovolt|kV]]/[[centimeter|cm]] (in air <ref>{{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}}</ref>) and 0.301 cm<sup>½</sup> respectively. This latter law can be considered to hold also in different setups, where the corresponding voltage is different due to geometric reasons. | |||
== References == | |||
{{reflist}} | |||
* {{cite book | author=F.W. Peek | title=Dielectric Phenomena in High Voltage Engineering | url=http://www.ee.vill.edu/ion/p183.html | publisher=McGraw-Hill | year=1929}} | |||
* [http://print.google.com/print?id=jDn78ePM-nwC High Voltage Engineering Fundamentals], E.Kuffel and WS Zaengl, Pergamon Press, p366 | |||
[[Category:Plasma physics]] | |||
Revision as of 16:52, 2 June 2013
In physics, Peek's law defines the electric potential gap necessary for triggering a corona discharge between two wires:
ev is the "visual critical corona voltage" or "corona inception voltage" (CIV), the voltage required to initiate a visible corona discharge between the wires.
mv is an irregularity factor to account for the condition of the wires. For smooth, polished wires, mv = 1. For roughened, dirty or weathered wires, 0.98 to 0.93, and for cables, 0.87 to 0.83, namely the surface irregularities result in diminishing the corona threshold voltage.
r is the radius of the wires in cm.
S is the distance between the wires
δ is the air density factor with respect to SATP (25°C and 76 cmHg):
gv is the "visual critical" electric field, and is calculated by the equation:
- where g0 is the "disruptive electric field", and c is an empirical dimensional constant. The values for those parameters are usually considered to be about 30-32 kV/cm (in air [1]) and 0.301 cm½ respectively. This latter law can be considered to hold also in different setups, where the corresponding voltage is different due to geometric reasons.
References
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My blog: http://www.primaboinca.com/view_profile.php?userid=5889534 - High Voltage Engineering Fundamentals, E.Kuffel and WS Zaengl, Pergamon Press, p366