Drive system for a rail vehicle having - a transformer, - a main switch and - a mains connection, wherein the main switch is arranged between the mains connection and a primary winding of the transformer, wherein the mains connection of the drive system is connected electrically with a current collector, and wherein the rail vehicle is provided for operation in an alternating voltage network with an alternating voltage of 15 kV or 25 kV, characterised in that the transformer has a short circuit voltage (u k) of at most 25%, wherein the main switch has a first series connection of at least two power semiconductors (21, 21a, 21b), wherein by means of a first power semiconductor of the at least two power semiconductors, a current (I 1,to) through the first series connection can be switched off in the direction from the mains connection to the transformer and by means of a second power semiconductor of the at least two power semiconductors, a current (I 1, back) through the first series connection can be switched off in the direction from the transformer to the mains connection, wherein the drive system has a protection device, with which a mains current (i Mains) can be detected, which flows from the mains connection to the transformer, wherein the protection device is connected to the main switch so that if a limit value (I Lim) is exceeded through the mains current (i Mains), the main switch can be triggered. - a transformer, - a main switch and - a mains connection, wherein the main switch is arranged between the mains connection and a primary winding of the transformer, wherein the mains connection of the drive system is connected electrically with a current collector, and wherein the rail vehicle is provided for operation in an alternating voltage network with an alternating voltage of 15 kV or 25 kV, characterised in that the transformer has a short circuit voltage (u k) of at most 25%, wherein the main switch has a first series connection of at least two power semiconductors (21, 21a, 21b), wherein by means of a first power semiconductor of the at least two power semiconductors, a current (I 1,to) through the first series connection can be switched off in the direction from the mains connection to the transformer and by means of a second power semiconductor of the at least two power semiconductors, a current (I 1, back) through the first series connection can be switched off in the direction from the transformer to the mains connection, wherein the drive system has a protection device, with which a mains current (i Mains) can be detected, which flows from the mains connection to the transformer, wherein the protection device is connected to the main switch so that if a limit value (I Lim) is exceeded through the mains current (i Mains), the main switch can be triggered. wherein the main switch is arranged between the mains connection and a primary winding of the transformer, wherein the mains connection of the drive system is connected electrically with a current collector, and wherein the rail vehicle is provided for operation in an alternating voltage network with an alternating voltage of 15 kV or 25 kV, characterised in that the transformer has a short circuit voltage (u k) of at most 25%, wherein the main switch has a first series connection of at least two power semiconductors (21, 21a, 21b), wherein by means of a first power semiconductor of the at least two power semiconductors, a current (I 1,to) through the first series connection can be switched off in the direction from the mains connection to the transformer and by means of a second power semiconductor of the at least two power semiconductors, a current (I 1, back) through the first series connection can be switched off in the direction from the transformer to the mains connection, wherein the drive system has a protection device, with which a mains current (i Mains) can be detected, which flows from the mains connection to the transformer, wherein the protection device is connected to the main switch so that if a limit value (I Lim) is exceeded through the mains current (i Mains), the main switch can be triggered.