Safety relay output expansion for enabling circuits
The Siemens 3SK1211-1BB00 is a SIRIUS safety relay output expansion module designed for relay enabling circuits in safety-related control systems. It provides 5 A switching capability at 24 V, 115 V, or 230 V, making it suitable for isolating safety zones in machinery guarding applications per IEC 60947-5-1. Rated for 24 V control voltage with an operating range of 0.85 to 1.1 times the rated value at both 50 Hz and 60 Hz, this module ensures reliable pick-up and drop-out across typical line variations. The typical response time is 45 ms, with a maximum of 50 ms, which governs the safety reaction time in the monitored circuit.
The 22.5 mm wide housing snaps onto a DIN rail using the screw and snap-on mounting method, fitting standard enclosure layouts. Screw-type terminals accept solid wire: 1x (20... 14 AWG) or 2x (18... 16 AWG); with ferrule, 1x (0.5... 2.5 mm²) or 2x (0.5... 1.0 mm²). Depth of 121.6 mm and height of 100 mm leave clearance for wiring ducts and adjacent modules. The total current through the module is limited to 12 A maximum, with a power loss of 2.5 W — factor this into enclosure thermal calculations.
Shock resistance is rated at 10g for 11 ms, and relative humidity tolerance spans 10 to 95 % during operation. The module has no delayed switching function — it responds immediately on the enabling circuit.