Many state-of-the-art devices, e.g. washing machines or heat pumps, use single-phase frequency converters. These can generate residual currents at the output side, caused by a mixture of frequencies with frequency components in the kilohertz range. RCCBs, type F are best suited for this purpose, since they expand the range of functions offered by type A. They have an impulse withstand strength of > 3 kA and a current carrying capacity of up to 10 mA with smooth DC residual currents.