Siemens 3TK2845, Manual

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Functional Information
3TK2845 Multifunction Device Manual
GWA 4NEB 926 2087-22 DS 01
2-13
2.2.2 3TK2845-.DB.. "Monitored Start-Up"
The 3TK2845-.DB.. has two sensor inputs (S1, S2 with monitored start-up), one
cascading input (CAS/OS with automatic start-up) as well as one switching input
(key-operated switch). On the output side there are two relay and two electronic
enabling circuits as well as an electronic signaling output.
Standard operation
In standard operation (key-operated switch "OFF") all enabling circuits are
activated. All input blocks are AND-connected to one another and affect all
enabling circuits at the same time, whereby some are time-delayed.
Maintenance
During maintenance (key-operated switch "ON") only two of the four enabling
circuits are activated. In this case, sensor input S2 (e.g. protective door) has no
function. The hazardous area can be entered since the dangerous motion has
been switched off via the two inactive enabling circuits. The sensor input S1 and
the cascading input CAS/OS still affect the active enabling circuits.