Trolleybus Skoda 9 Tr Lot of cities nowadays invest in more environmental friendly public transportation. Due to that trolleybuses experienced a renaissance in the last couple of years. Many cities that used to have trolleybus lines and discontinued their operation are now returning to this means of transport. However, today Read more…
Network harmonics: Mitigation methods Today’s post focuses on harmonic mitigation methods. Let us review the most common, well proven methods of minimization of harmonic distortion on the grid side. Previous articles presented a general view on harmonics, their origin and effects [1]. The grid side harmonic spectrum of VFDs had Read more…
VFD harmonic spectrum Introduction After the theoretical introduction [1] we jump to variable frequency drives as sources of harmonics. This post is about VFD harmonic spectrum. As already mentioned, VFDs belong to non-linear devices with non-sinusoidal currents and/or voltages that they draw from the grid or inject into the grid. Read more…
Transformer winding connection, clock number and vector group This article explains the winding connections, clock number and vector group of phase-shifting transformers used to supply variable frequency drives (VFD). Motivation Some of the most common keywords that bring the readers to our webpage are associated with multi-winding transformers, their connection Read more…