A multilevel converter converting between AC and DC includes a phase leg having a first and a second phase arm, the first phase arm being connected between a first pole having a first potential and a first AC terminal and the second phase arm being connected between the first AC terminal and a second potential, where the phase arms include half-bridge and full-bridge cells, where each cell includes at least one energy storage element for providing the voltage contribution and cell switching units with cell switches and anti-parallel diodes for controlling the voltage contribution, where the full-bridge cells include a bypass switch controllable to bypass the corresponding energy storage element, and when a phase-to-ground fault occurs the cell switches are blocked and the bypass switches activated with a delay in relation to the blocking.