Auxiliary switch 1 changeover contact + fault signal switch 1 changeover contact 230/400V AC / 24-220V DC 0.5 TE. for 5SY, 5SL for 5SP, 5SV, 5SU1, 5ST3 Auxiliary and fault signal switch SENTRON 5ST3 as an additional component for residual current protective devices and circuit breakers. These additional components can be mounted universally. They are easy and convenient to install and connect. Thanks to the standard touch protection, safety during installation is reliably guaranteed. Optimum technology for your safety - only from Siemens.