Lastkrets

Lastkrets is a term used in Swedish electrical engineering and electronics to denote the portion of an electrical circuit that consumes electrical power. It is the counterpart to the power source or driving circuit, which delivers energy to the system. The concept is applied across both simple and complex circuits.

A lastkrets can include resistive, reactive, or mixed loads, such as lamps, motors, heating elements, or power-electronic devices. In circuit analysis the load determines the current drawn from the source according to Ohm’s law and its variations, and it defines the power that is dissipated or used. In alternating current circuits the load often has impedance with a possible phase angle, affecting voltage, current, and power factor.

In design and testing, the lastkrets is central to considerations of regulation, efficiency, and protection. The characteristics of the load influence how voltage and current behave under different conditions, how the supply regulates under varying demand, and what protection schemes are appropriate (fuses, breakers, overcurrent protection). The concept also appears in more advanced analyses, such as load lines for transistor or amplifier designs and, in power systems, the distinction between the source side and the load side of a network. The term is commonly used in Swedish technical literature and schematics as the element of the circuit where electrical energy is consumed.

See also: load (electrical engineering)