A converter arrangement comprising: a power converter; circuit breakers configured to be connected to an AC mains; converter terminals for connecting the power converter to the AC mains via the circuit breakers; and an auxiliary power supply arrangement comprising: switches arranged to connect the power supply arrangement to the converter terminals; an auxiliary power supply and charging breakers, wherein the auxiliary power supply is connected via the charging breakers to the converter terminals between the power converter and the circuit breakers, wherein the auxiliary power supply is configured for charging gate units of cell switches of at least one converter cell of the power converter during start-up of the power converter; a transformer for increasing the voltage from the auxiliary power supply to the power converter, wherein the transformer is connected between the charging breakers and the switches of the auxiliary power supply arrangement; and a capacitor arrangement (4a, 4b) comprising at least one capacitor, connected between the charging breakers and the converter terminals on the low-voltage side of the transformer and/or on the high-voltage side of the transformer; wherein the capacitor arrangement is configured to protect semiconductors of the cell switches from voltage surges (dv/dt) during the start-up of the power converter. a power converter; circuit breakers configured to be connected to an AC mains; converter terminals for connecting the power converter to the AC mains via the circuit breakers; and an auxiliary power supply arrangement comprising: switches arranged to connect the power supply arrangement to the converter terminals; an auxiliary power supply and charging breakers, wherein the auxiliary power supply is connected via the charging breakers to the converter terminals between the power converter and the circuit breakers, wherein the auxiliary power supply is configured for charging gate units of cell switches of at least one converter cell of the power converter during start-up of the power converter; a transformer for increasing the voltage from the auxiliary power supply to the power converter, wherein the transformer is connected between the charging breakers and the switches of the auxiliary power supply arrangement; and a capacitor arrangement (4a, 4b) comprising at least one capacitor, connected between the charging breakers and the converter terminals on the low-voltage side of the transformer and/or on the high-voltage side of the transformer; wherein the capacitor arrangement is configured to protect semiconductors of the cell switches from voltage surges (dv/dt) during the start-up of the power converter. switches arranged to connect the power supply arrangement to the converter terminals; an auxiliary power supply and charging breakers, wherein the auxiliary power supply is connected via the charging breakers to the converter terminals between the power converter and the circuit breakers, wherein the auxiliary power supply is configured for charging gate units of cell switches of at least one converter cell of the power converter during start-up of the power converter; a transformer for increasing the voltage from the auxiliary power supply to the power converter, wherein the transformer is connected between the charging breakers and the switches of the auxiliary power supply arrangement; and a capacitor arrangement (4a, 4b) comprising at least one capacitor, connected between the charging breakers and the converter terminals on the low-voltage side of the transformer and/or on the high-voltage side of the transformer; wherein the capacitor arrangement is configured to protect semiconductors of the cell switches from voltage surges (dv/dt) during the start-up of the power converter.