Assembly for securing an electrical external power supply connector

An assembly secures a connector of an external power supply in a rail vehicle. The connector is enclosed by a housing and by a rotatably mounted flap. The flap and the housing each have a slot configured to receive a catch. The flap can have two positions: a first position, in which the flap covers the connector and thus prevents access to the connector, and a second position, in which access to the connector is possible. The flap supports a lock cylinder, which can be switched by a key into two states: in a first state, the key can be pulled out of the lock cylinder, and in a second state, the key is secured in the lock cylinder against removal. A catch is rotated into both slots or out of both slots by the lock cylinder.