The Siemens 3SE5112-0BD02 is a SIRIUS mechanical position switch with a roller plunger actuator, designed for positive opening of the normally closed contacts. It is a current-production part, still actively manufactured. The metal enclosure carries IP66/IP67 protection, meaning the switch body and the actuator seal withstand direct hose-down and temporary immersion — suitable for washdown zones in food processing, packaging lines, and outdoor conveyor transfer points. The actuator head conforms to EN 50041 design C, a standard interface for industrial limit switches, so it mounts directly to existing brackets and cams without adapter plates.
The thermal current (Ith) is rated 10 A, which is the continuous current the contacts can carry in free air. The switching capacity depends on voltage: 6 A at 240 V AC, 3 A at 24 V DC, and derated to 0.12 A at 400 V AC. For a 24 V DC control circuit, the 3 A rating covers most PLC input modules and relay coils directly. Repeat accuracy is specified at 0.05 mm, meaning the switch triggers at virtually the same actuator position on every cycle. This matters for cam-follower applications where consistent timing of the switching point is required — for example, detecting a carriage at end-of-travel within a tight window. The slow-action contacts with positive opening (per IEC 60947-5-1) guarantee that the NC contact physically breaks even if welded. This is a safety function: the switch can be used in a safety circuit where the NC channel must open reliably when the actuator is depressed. The switch can be installed in unheated outdoor enclosures or near hot machinery surfaces, as long as the ambient at the switch body stays within the operating band.
The switch is fastened by screw fixing (two M4 or M5 bolts through the slotted holes in the metal base). The housing is a narrow block design, 40 mm wide and 116.3 mm long, with a rounded switch head. The cathodic dip coating on the metal enclosure provides corrosion resistance in humid or mildly aggressive atmospheres.
The switch carries a RoHS substance prohibitance date of July 1, 2006, confirming compliance with the EU RoHS directive.