Medium voltage drives are essential technology for various high power demanding industrial applications. To satisfy ever increasing customer demands, a power extension of the Integrated Gate Commutated Thyristor (IGCT) based 3L-NPC inverter unit, has been recently performed, resulting in 12 MVA continuous power ratings with 13 MVA short-term overload, at 3.3 kV output voltage. Higher output power can be further reached by paralleling several units. This paper presents some design details of the inverter unit together with experimental results obtained during type testing and commissioning.