Lastabwurf

Lastabwurf, in electrical power engineering, refers to the intentional disconnection of selected electrical loads to prevent larger-scale power system instability or blackout when generation is insufficient or transmission capacity is overstressed. It is a protective measure used in transmission and distribution networks. The aim is to maintain system frequency and voltage within safe limits by shedding non-essential demand in a controlled, staged manner.

Load shedding is typically organized in stages (Stufen). The most critical loads, such as hospitals, water supply, and essential public services, are kept connected as long as possible; less critical loads—industrial processes, commercial lighting, and non-essential climate control—are disconnected according to predefined priority lists. In smart grids, automation and demand-side management allow more selective shedding of customer groups rather than entire feeders.

Triggers include generation shortfalls, loss of a major transmission path, extreme demand, or grid faults. Protection systems monitor frequency, voltage, and line load and initiate automatic Lastabwurf when thresholds are exceeded. Operations can be manual or automated and are coordinated by the transmission system operator with input from regional grid controls and market operators.

Impact and limitations: Lastabwurf prevents wider outages but causes service interruption for consumers and industries. Modern grids aim to minimize disruptions through energy efficiency, storage, demand response, and more granular shedding schemes.