Residual current operated circuit-breakers with integral overcurrent protection (RCBO) are miniature circuit-breakers with residual current trips for protecting systems in the event of a short-circuit and overload as per the requirements of VDE 0100 Part 430, and for protecting persons, farm animals and material items in the event of earth leakage currents as per VDE 0100 Part 410. Overload tripping occurs at currents in the overload range through a slow-blow, heat-sensitive bimetal trip and at short-circuit currents through an electromagnetic instantaneous trip. RCBOs with residual current characteristic B detect smooth DC residual currents as well as all other type B residual currents as per IEC 60755. The evaluation unit integrated for this purpose required an operating voltage taken from the mains supply. Correct power supply to the evaluation unit is ensured when the voltage between the mains conductors is ? 50 V. Type A residual currents are detected regardless of the mains voltage. Furthermore, these RCBOs completely detect residual currents of all frequencies up to 100 kHz. With the wide frequency range for residual current detection, these devices more than meet the requirements for the applicable design standards for type B or B+ residual current circuit-breakers. For switches with characteristic curve NK, the tripping current frequency response runs below human tolerance levels for shock currents with different frequencies