Voltage Harmonic Distortion at Buses Feeding Office Loads

The total harmonic distortion of the phase-to-neutral voltage at buses feeding office load is investigated for various cable configurations, lengths and cross-sections. The investigation is carried out with a software model which was validated with approximate analytical expressions and measurements taken at a real installation. It is shown that the selection of a cable should based not only on its ampacity and allowable voltage drop but its configuration should be taken into account in order to avoid excessive voltage harmonic distortion. Configurations where the neutral conductor is part of a four-core cable cause relatively small harmonic distortion while cable configurations where the neutral conductor runs separately cause high voltage harmonic distortion.