Lasttrennschaltern

Lasttrennschalter, in English often called a load-break disconnect switch, are electrical switching devices used to isolate a load from its power source while allowing current to be interrupted as needed. They are designed to provide a visible disconnect and a safe mechanical isolation even when the circuit is energized, distinguishing them from pure isolators that are not intended to break current.

Function and construction: Lasttrennschalter are capable of interrupting current (break under load) and are equipped with contact systems and an arc interruption mechanism. The arcing is extinguished by media appropriate to the design, such as air, vacuum, or insulating gas. They are commonly integrated into medium- and low-voltage switchgear and may appear as standalone units or as part of a bay in substations or industrial plants.

Operation and interlocks: The device can be manually operated or motor-driven. It includes interlocks to ensure safe operation, preventing closing when a feeder is not isolated and preventing opening while a disconnect may expose energized parts. Some designs may be combined with fuses or be part of a broader protective arrangement.

Applications: Lasttrennschalter are used to isolate circuits for maintenance, sectionalize networks, or enable switching under load within protection coordination schemes. They provide faster and more controlled disconnection than simple isolators, at the cost of higher complexity and maintenance needs.

Standards and variants: They are specified under international switchgear standards, such as the IEC 62271 series, and are produced in various voltage classes and breaking capacities to suit different installation requirements.