The invention relates to a device and to a method for monitoring an electrical network in a rail vehicle. The electrical network includes at least one converter, at least one drive motor, at least one first phase line for electrical connection of the at least one converter and the at least one drive motor. A magnitude of a current change of a first phase current is determined. A network error in a partial network on the machine side is detected if at least one criterion based on the current change is met. The criterion based on a current change is met when the magnitude of the current change of the first phase current is greater than a predetermined current change threshold.