Main circuit breaker (SHU), 3x 1-pole, E 40A, 230/400V Installation on 40mm busbars The circuit breaker is the automatic circuit breaker for short-circuit protection Siemens circuit breakers are an important part of the SENTRON protection components for electrical installations and offer effective protection for people and systems by safely switching off in the event of overload and short circuits. Convenient installation and connection technology, uniform additional components and a consistent design - these are the characteristics of the device family. Whether for infrastructure or industrial requirements, Siemens offers circuit breakers for all applications and every area of use. Siemens circuit breakers are characterized above all by: 1. Effective protection for people, investments and systems against overload and short circuits. 2. Reliable safety during installation thanks to the standard anti-reach and touch protection. 3. Clearly visible switch position display. 4. Optimum technology for your safety - only from Siemens.