Levels of magnetic fields from higher harmonic components of rectified current

Abstract

The article presents the sources of electromagnetic fields which have harmful effects on the electrical engineering personnel servicing electric plants. The authours consider, depending on the rectification circuit (6, 12, 24 pulse) –the  range of higher harmonic components of the rectified current, 12-pulse converters, in addition to the main harmonic with a frequency of 50 Hz of electrical alternating current rectifier, have higher harmonic components of the rectified current with frequencies starting from the eleventh (11; 13; 23; 25, etc.) in the primary curve of the rectified current, while 24-pulse converters, in addition to the main harmonic with 50 Hz frequency, have higher harmonic components of the rectified current with frequencies from the twenty-third (23; 25, etc.) in the primary curve of the rectified current.It is shown that the safest from the point of view of
the magnetic field impact on the electrical staff of the traction power supply is a 24-pulse rectifier having a mi­nimum frequency range: 50 Hz, 1150 Hz, 1250 Hz.

The calculation of the magnetic field of the rectified current on the work stations in the area of “+” and “–” bus of RU-3.3 kV with the superposition method without taking into account the influence of the earth. It is revealed that at traction substations, even in the presence of a smoothing filter unit, the personnel is influenced by a number of harmonic components of the magnetic field of the rectified current the maximum allowable levels of which are not currently standardized in Russia and their harmful effects on the electrical staff has not been considered until recently.