Lastwiderstands

Lastwiderstände, or load resistors in English, are resistors used to provide a defined electrical load to an electrical circuit. They dissipate electrical energy as heat and are employed to test, characterize, or stabilize power supplies, amplifiers, and other equipment. By drawing a known current at a given voltage, they help simulate real-world loading conditions and enable safe, repeatable measurements.

Typical forms include fixed power resistors made from materials such as wire-wound, metal oxide, or ceramic, which come in various power ratings and resistance values. High-power or specialized dummy-load assemblies may include dedicated cooling like fins or fans. Adjustable variants, such as power rheostats, allow coarse tuning of the load. For RF applications, dedicated dummy-loads are designed to operate over specific frequency ranges and with controlled impedance.

Key design and selection considerations include the resistance value (R), which sets the current at a given voltage, and the power rating (P), which must exceed the expected dissipation with ambient temperature considered. Derating is often necessary as temperature rises. The temperature coefficient and tolerance influence precision, while mounting, enclosure, and cooling affect performance and safety.

Applications span laboratory testing of power supplies and electronic equipment, battery discharge testing, and as safe, controllable loads in developmental and educational settings. Proper handling includes managing heat, ensuring adequate ventilation, and observing safety guidelines for high-power components. See also: Resistor, Dummy load, Power resistor.