Lastkreis

Lastkreis is a term used in German electrical engineering and instrumentation to denote the portion of a circuit that contains the load—the devices or systems that consume electrical power. It is typically contrasted with the source side and with measurement or control circuits. The exact boundary between the Lastkreis and the rest of the system depends on the context, but it generally refers to the consumers and the wiring that feeds them.

In measurement and control technology, the Lastkreis is important because the load impedance interacts with the source and sensing elements. The performance of a signal path can be affected by loading effects, voltage drops, and time constants. Designers aim to minimize adverse loading by ensuring appropriate impedance matching, buffering, or isolation, so that the measurement or control signal remains accurate and responsive.

In power distribution and building technology, the Lastkreis describes the consumer-side network fed by a distribution board, including outlets, motors, heating elements and other loads. Protection schemes, conductor sizing, and energy management are planned with the Lastkreis in mind to ensure safe operation and reliable supply. The term emphasizes the practical role of the portion of the circuit where electrical power is converted into useful work.

Originating from the German words load (Last) and circuit (Kreis), Lastkreis is used across engineering fields to distinguish the load-carrying portion of a system from its source and measurement sections. Usage varies by field, and some authors may use related phrases such as lastseitiger Kreis.