Transformer support structure for mounting a transformer assembly comprising: a bottom element (120; 120a) having a support surface with a horizontal orientation including two longitudinal side edges (160a, 160b) which delimit the support surface, wherein the longitudinal side edges (160a, 160b) run parallel to each other in a y-direction; a cross bar (200; 200a) being supported on the support surface, the cross bar (200; 200a) runs crosswise to the longitudinal side edges (160a, 160b); and at least two plate-shaped reinforcement units (300a, 300b) for reinforcing the cross bar (200; 200a), the at least two reinforcement units (300a, 300b) extend over a major part of an outer front surface of the cross bar (200; 200a) in a vertical z-direction, wherein the reinforcement units (300a, 300b) are positioned above the longitudinal side edges (160a, 160b) and are aligned with the longitudinal side edges (160a, 160b) such that a first one of the at least two plate-shaped reinforcement units is aligned to a first one of the longitudinal side edges and a second one of the at least two plate-shaped reinforcement units is aligned to a second one of the longitudinal side edges, wherein the cross bar (200; 200a) has a C-shaped cross section along a y-z plane forming a middle vertical portion of the C-shaped cross section of the outer front surface, an upper horizontal surface of the C-shaped cross section and a lower horizontal surface of the C-shaped cross section, wherein the upper and the lower horizontal surfaces face each other or wherein the cross bar has a L-shaped cross section along a y-z plane forming a middle vertical portion of the L-shaped cross section of the outer front surface and a lower horizontal surface of the L-shaped cross section, wherein being aligned with the longitudinal side edge (160a, 160b) is to be understood that the sum of a distance between a vertical axis (305a, 305b) crossing the respective longitudinal side edge (160a, 160b) and an inner edge of the reinforcement unit (300a, 300b) facing the respective other reinforcement unit and a distance between the vertical axis (305a, 305b) and an outer side edge (303a, 303b) of the reinforcement unit (300a, 300b) is equal or smaller than a distance between the outer side edge (303a, 303b) of the reinforcement unit (300a, 300b) and the inner edge of the reinforcement unit (300a, 300b). a bottom element (120; 120a) having a support surface with a horizontal orientation including two longitudinal side edges (160a, 160b) which delimit the support surface, wherein the longitudinal side edges (160a, 160b) run parallel to each other in a y-direction; a cross bar (200; 200a) being supported on the support surface, the cross bar (200; 200a) runs crosswise to the longitudinal side edges (160a, 160b); and at least two plate-shaped reinforcement units (300a, 300b) for reinforcing the cross bar (200; 200a), the at least two reinforcement units (300a, 300b) extend over a major part of an outer front surface of the cross bar (200; 200a) in a vertical z-direction, wherein the reinforcement units (300a, 300b) are positioned above the longitudinal side edges (160a, 160b) and are aligned with the longitudinal side edges (160a, 160b) such that a first one of the at least two plate-shaped reinforcement units is aligned to a first one of the longitudinal side edges and a second one of the at least two plate-shaped reinforcement units is aligned to a second one of the longitudinal side edges, wherein the cross bar (200; 200a) has a C-shaped cross section along a y-z plane forming a middle vertical portion of the C-shaped cross section of the outer front surface, an upper horizontal surface of the C-shaped cross section and a lower horizontal surface of the C-shaped cross section, wherein the upper and the lower horizontal surfaces face each other or wherein the cross bar has a L-shaped cross section along a y-z plane forming a middle vertical portion of the L-shaped cross section of the outer front surface and a lower horizontal surface of the L-shaped cross section, wherein being aligned with the longitudinal side edge (160a, 160b) is to be understood that the sum of a distance between a vertical axis (305a, 305b) crossing the respective longitudinal side edge (160a, 160b) and an inner edge of the reinforcement unit (300a, 300b) facing the respective other reinforcement unit and a distance between the vertical axis (305a, 305b) and an outer side edge (303a, 303b) of the reinforcement unit (300a, 300b) is equal or smaller than a distance between the outer side edge (303a, 303b) of the reinforcement unit (300a, 300b) and the inner edge of the reinforcement unit (300a, 300b).