Multiphase operated or frequency-controlled electronic equipment such as cranes, pumps, fans, compressors, vibrators, charging stations for electric vehicles or also photovoltaic systems can also cause smooth DC residual currents in the event of a fault. All-current sensitive residual-current circuit-breakers are also the optimal protection when consumers with operating frequencies up to the kilohertz range are used. They are specified by many standards and are an important contribution to safety when using electricity, especially on construction sites. We offer the Type B RCCB in SK and NK versions. If no fire protection is required or desired, we recommend the Type B SK for maximum system availability. If fire protection is required, the Type B NK must be used.