3TY7561-1AA00 3TF6 Auxiliary Contact Block – 1NC + 1NO. The Siemens 3TY auxiliary switch has a centrally positioned release lever for disassembly. One 2-pole or up to two 1-pole auxiliary switches (screw or spring-type terminals) can be snapped on. When the contactors are switched on, the NC contacts are opened first and then the NO contacts are closed.