Peek's law

In physics, Peek's law defines the electric potential gap necessary for triggering a corona discharge between two wires: 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 center of the wires. gv is the 'visual critical' electric field, and is given by: δ is the air density factor with respect to SATP (25°C and 76 cmHg): g0 is the 'disruptive electric field.' c is an empirical dimensional constant.