RC unit for 5SY, 4-pole, type AC, In: 40 A, 300 mA, Un AC: 400 V The RCD is the residual current device for touch protection. The patented residual current protective devices from Siemens are an important component of the SENTRON protective devices for electrical installations because they prevent life-threatening electrical accidents by safely disconnecting hazardous residual currents through grounding. Electrically ignited fires can be prevented as they occur. Whether by direct contact with energized operating parts or by indirect contact with equipment, protection is mainly achieved by a quick shutdown. The residual current operated circuit breakers are characterized primarily by: 1. Comprehensive protection from electric shock for personnel and property. 2. Whether sinusoidal residual alternating currents or smooth residual direct currents, Siemens provides the right type for all requirements and special versions. 3. Be protected according to the standards: All residual current operated circuit breakers correspond to the provisions of DIN VDE. 4. Optimized technology for your safety – only from Siemens.