Quantities, units and formulas

IEEE 1159-2019 treats power frequency variation as the deviation of the fundamental frequency from its nominal value, a quantity that follows the balance between load and generation and that Table 2 lists as its final category.

In IEEE 519-2022 the maximum demand load current is established at the point of common coupling as the average of the monthly maximum demand currents over the previous twelve months, each monthly value being the rms current corresponding to the maximum demand over the averaging window stated in the definition.

In IEEE 519-2022 the short circuit ratio at a location is the available short circuit current divided by the maximum demand load current, both in amperes, which makes the ratio dimensionless.

In IEEE 519-2022 the telephone influence factor of a voltage or current wave is the ratio of the root of the sum of the squares of the weighted rms values of all its sine wave components, fundamental and harmonics, to the unweighted rms of the whole wave, with a weighting that combines C-message weighting and a term proportional to frequency.

Total demand distortion in IEEE 519-2022 is the rms of the harmonic current content, excluding interharmonics and taken up to the harmonic order stated in the definition, divided by the maximum demand load current and expressed as a percent, so that it differs from total harmonic distortion only in its denominator.

Total harmonic distortion in IEEE 519-2022 is the rms of the harmonic content of a voltage or current, excluding interharmonics and taken up to the harmonic order stated in the definition, divided by the fundamental and expressed as a percent.