539-1990 IEEE STANDARD DEFINITION OF TERMS RELATING TO CORONA AND FIELD EFFECTS OF OVERHEAD POWER LINES

The objective of this IEEE standard entitled Standard Definition of Terms Relating to Corona and Field Effects of Overhead Power Lines is to obtain uniformity in the use of terms relating to the areas of corona and the electromagnetic environment of power lines. Its scope is to define the most widely used terms specific to or associated with overhead power-line corona and fields.

Here, we are focus more on terms that are relevant to Power System's Loss topic like corona and electric fields that can influence the level of losses in a transmission line. For a complete access on the said standard, you can refer to the link below for the pdf copy.

Some of the sample terms found in the standard are as follows;

All Weather DistributionA distribution of corona-effect data collected under all weather conditions. Such data are usually obtained from longterm recording stations. Weather conditions are defined in the next section.

AC Electric Field StrengthThe electric field strength produced by ac power systems as defined by its space components along three orthogonal axes. For steady-state sinusoidal fields, each component can be represented by a complex number or phasor. The magnitudes of the components are expressed by their rms values in volts per meter, and their phases need not be the same.

DC Electric Field StrengthThe time-invariant electric field, produced by dc power systems and space charge, defined by its space components along three orthogonal axes. The magnitudes of the components are expressed in volts per meter. Syn: dc electric field.

Electric Potential Difference
The line integral of the scalar product of the electric field strength vector and the unit vector along any path from one point to the other, in an electric field resulting from a static distribution of electric charge. Syn: electrostatic potential difference.

Average Bundle Gradient
For a bundle of two or more subconductors, the arithmetic mean of the average gradients of the individual
subconductors.

Average Maximum Bundle Gradient
For a bundle of two or more subconductors, the arithmetic mean of the maximum gradients of the individual
subconductors. For example, for a three-conductor bundle with individual maximum subconductor gradients of 16.5, 16.9, and 17.0 kV/cm, the average maximum bundle gradient would be (1/3) (16.5 + 16.9 + 17.0) = 16.8 kV/cm.

Maximum Bundle Gradient
For a bundle of two or more subconductors, the highest value among the maximum gradients of the individual
subconductors. For example, for a three-conductor bundle with individual maximum subconductor gradients of 16.5, 16.9, and 17.0 kV/cm, the maximum bundle gradient would be 17.0 kV/cm.

Corona Inception Voltage
The voltage applied to the electrode to produce the corona inception gradient.

Ionization
The process by which an atom or molecule receives enough energy (by collision with electrons, photons, etc.) to split it into one or more free electrons and a positive ion. Ionization is a special case of charging.

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