Zwischenlast

Zwischenlast, literally “intermediate load,” is a term used in German engineering and energy management to describe a load level that lies between the base load (Grundlast) and the peak load (Spitzenlast). The exact meaning varies by discipline, but it generally denotes a non-permanent, time-varying or intermediate magnitude of load used for planning, design, or operation.

In power systems, Zwischenlast refers to an intermediate demand level that occurs during the day or across seasons, influenced by factors such as weather, occupancy, or industrial activity. Grid operators and planners use Zwischenlast scenarios to size equipment, schedule generation, and assess reliability beyond the extremes of base load and peak load. It helps in modeling typical operating conditions and in evaluating the performance of transformers, lines, and distributed energy resources under realistic conditions.

In structural engineering, the term may describe live loads that fluctuate between minimum and maximum values, used in load combination rules to ensure serviceability and safety. Here, Zwischenlast is considered alongside permanent loads (dead loads) and variable loads (live loads, environmental loads) to capture intermediate stress states.

In practice, the term is context-dependent and may be replaced by more precise phrases such as “intermediate load case,” “mid-load,” or “diurnal load” depending on national standards and the specific technical domain.

See also: Grundlast, Spitzenlast, Lastfall, Lastkombination.