Power electronics device, such as a frequency converter, comprising power units (REC1, INU1, INU2, CDC1), a metal frame (31) and a DC bus arrangement in which the power units are connected. The power units may be assembled inside the metal frame (31) wherein the shape of the metal frame is elongated with rectangular cross-sectional shape, consisting of a bottom part (33) and from that essentially vertical oriented side wall parts (32). The DC bus arrangement is arranged on top of the bottom part (33) of the metal frame (31) and separated by an insulator layer (S1) from the metal frame (31). The DC bus arrangement comprises a first DC bus current conductor (DC+) and a second DC bus current conductor (DC−) which are arranged apart from each other. The DC bus current conductors (DC+, DC−) have a flat shape in such a way that their thickness dimension is essentially shorter than their width dimension.