NETIO produces some products with several electrical socket types. The DE abbreviation then refers to products with Type F sockets.
110/230VAC sockets in a standard electrical wiring are protected with circuit breakers (or fuses) against short circuit or overload. When there is a power outage, circuit breakers sometimes trip when the power is restored if there are too many appliances with a switching power supply connected to the same circuit breaker. See Inrush current.
Digital Inputs are binary inputs (0 or 1) that are detected by the device. In simple words, any push-button, switches or sensors produces compatible digital output can be connected to the Digital Input.