Peek's law

About: Peek's law is a research topic. Over the lifetime, 137 publications have been published within this topic receiving 985 citations.

Theoretical Evaluation of Peek's Law

Abstract: A theoretical evaluation for Peek's law which yields the corona onset gradient is made in air for positive wire/cylinder and positive point/plane geometries The physical and geometrical parameters used in Meek's criterion take into account the variation of apparent ionization coefficient ?1 of air with humidity, pressure, and temperature and the curvature radius R of the rod tip (or the wire diameter D) A single analytic integrable expression is introduced for ?1/P which may be used for any value of the reduced field E/p The results covering a wide range of parameters 10-7 m < R or D < 107 m (up to a plane/plane geometry) are compared with a variety of experimental results

Positive corona inception voltages and corona currents for air at various pressures and humidities

Abstract: The variation of positive dc corona characteristics with air pressure and humidity using a point/plane electrode system was studied in a perspex chamber allowing the pressure and humidity to be varied. A method of calculation was developed to determine the corona current for humid air over a range of pressures and humidities in which the effective ionization coefficient was calculated as a linear interpolation of the effective ionization coefficients for dry air and water vapor. The calculation method involved the solution of partial differential equations using a particle-in-cell algorithm. This also allowed the determination of the corona inception voltages for a range of pressures and humidities as the voltage at which the corona current first appeared. The validity of these calculations was confirmed by a series of experimental determinations of the corona inception voltages and of the variation of the corona current with the applied voltage for the same range of pressures and humidities. It was found that the corona current increased when the air pressure or humidity decreased (at constant applied voltage) mainly because of the rise in the space charge density or the positive ion mobility, respectively. The coefficient C, in the relationship between the corona current, the applied dc voltage and the corona inception voltage, declined with the increase of humidity. The rate of decrease of C with humidity became larger as the pressure was reduced. An approximately inversely proportional relationship was found to exist between C and the relative air density at constant humidity. This variation of C was principally associated with the variation in the positive ion mobility.

Design optimization of high voltage bushing using electric field computations

Abstract: This paper illustrates the use of electric field computation to optimize the design of gas filled high voltage composite bushings. The United States Navy employs these bushings in high power very low frequency/low frequency transmitting stations. Commercially available 2D and 3D computational packages based on the boundary element method were employed to analyze the electric fields. The optimized design uses both internal and external elements for electric stress grading at critical parts of the bushing. It has been shown that the location and magnitude of the maximum electric field have been optimized which should result in a substantially higher corona free operating voltage

Negative corona inception voltages in rod-plane gaps at various air pressures and humidities

Abstract: The variation of negative dc corona inception voltages with air pressure and humidity, using a point/plane electrode system, was studied using a perspex chamber in which the pressure and humidity could be varied. A method of calculation was developed to determine the corona inception voltages over a range of air pressures and humidities. The effective ionization coefficient was calculated as a linear interpolation of the effective ionization coefficients for dry air and water vapor. The validity of these calculations was confirmed by a series of experimental determinations of the corona inception voltages for the same range of pressures and humidities. A comparison of the negative and positive corona inception mechanisms was also made. Both the negative and positive corona inception voltages decreased with a decrease in the air pressure and an increase in the humidity. The greater values of the effective ionization intensity found in the critical zone for the negative corona accounted for their lower inception voltages. The mechanisms of the affect of the photo-absorption coefficient and Townsend's second coefficient on the negative and positive corona were also considered.

Theory of electric corona including the role of plasma chemistry

Abstract: The traditional theory of corona is cast in terms of ionization and attachment coefficients and gives good quantitative predictions of the voltage for the onset of corona as a function of the diameter of the corona wires, temperature, pressureandcharacteristics of the gas. Furthermore, it gives a fair qualitative description of the corona discharge itself as a function of space and time. The motion of electrons, positive ions and negative ions formed by electron attachment, can produce distortions to the electric field by space charge effects which result inTrichel current pulses for negativevoltages and "streamers" for positive voltages. Recently it has been realized that the medium of the corona discharge in air, for example, is not ordinary air, since the properties of the air are changed by the corona discharge itself. Of particular importance for properties of the corona discharge are the many excited states and metastable atoms and molecules that are created by the corona discharge, which may influence the electron density by detachment of negative ions or make possible two-step ionization. Rate constants of those reactions of plasma chemistry, which involve electrons in the discharge, are a function of the local electric field. In the present paper, mechanisms of plasma chemistry are proposed to explain the voltage for spark breakdown between corona wires.