A modular multilevel converter (300, 400) for converting between a DC voltage and an AC voltage, the modular multilevel converter (300, 400) comprising - at least two phase units (102, 202) connected in parallel and connectable to a DC terminal, the phase units (102, 202) each comprising an upper converter arm and a lower converter arm, each converter arm (108, 112) having one or more cells (C, CF, CH) being arranged in series, wherein each cell (C, CF, CH) comprises an energy storage element and a switching arrangement adapted to switching the energy storage element in or out of the series of cells (C, CF, CH), - a control unit being adapted to control the switching arrangements of the cells (C, CF, CH), - a middle converter arm arranged in series between the upper and lower converter arm (108, 112), the middle converter arm having one or more cells (C, CF, CH) being arranged in series, - an upper node between said upper and middle converter (108, 110) arm and a lower node between said lower and middle converter arm (112, 110), - an upper bridging element arranged between said upper node and an AC terminal, - a lower bridging element arranged between said lower node and said AC terminal, - a second upper bridging element arranged between said upper node and said AC terminal, - a second lower bridging element arranged between said lower node and said AC terminal, - a first disconnector between the middle point of the upper and lower bridging element (118, 124) and the AC terminal and a second disconnector between the middle point of the second upper and lower bridging element (218, 224) and the AC terminal, wherein the bridging elements (118, 124, 218, 224) can be switched on and off and the disconnectors (206, 210) may be opened to disconnect particular bridging elements. - at least two phase units (102, 202) connected in parallel and connectable to a DC terminal, the phase units (102, 202) each comprising an upper converter arm and a lower converter arm, each converter arm (108, 112) having one or more cells (C, CF, CH) being arranged in series, wherein each cell (C, CF, CH) comprises an energy storage element and a switching arrangement adapted to switching the energy storage element in or out of the series of cells (C, CF, CH), - a control unit being adapted to control the switching arrangements of the cells (C, CF, CH), - a middle converter arm arranged in series between the upper and lower converter arm (108, 112), the middle converter arm having one or more cells (C, CF, CH) being arranged in series, - an upper node between said upper and middle converter (108, 110) arm and a lower node between said lower and middle converter arm (112, 110), - an upper bridging element arranged between said upper node and an AC terminal, - a lower bridging element arranged between said lower node and said AC terminal, - a second upper bridging element arranged between said upper node and said AC terminal, - a second lower bridging element arranged between said lower node and said AC terminal, - a first disconnector between the middle point of the upper and lower bridging element (118, 124) and the AC terminal and a second disconnector between the middle point of the second upper and lower bridging element (218, 224) and the AC terminal,