The Siemens 3RK1903-1BA00 is a PM-D F1 fail-safe power module from the Local Safety Modules series, designed for monitored start and emergency-stop safety circuits. Rated SIL CL 3 per IEC 61508 and Category 4 per EN ISO 13849-1, with a safe failure fraction of 99 % and average diagnostic coverage of 99 %, this module achieves a PFHD of 8.7E-9 1/h — well within the high-demand SIL 3 range, meaning it can be used in safety functions where the probability of dangerous failure per hour must be below 1E-8. The safe state is load circuit open, and the hardware fault tolerance is 1 (Type B device per IEC 61508-2), so a single fault in the module does not lead to loss of the safety function.
Supply and integration
Operates on a 20.4... 28.8 V DC control supply. The 30 mm width matches the TM-PF30 footprint. Bus communication is supported, allowing the safety module to exchange status with the higher-level controller over the local bus backbone. Mechanical service life is rated at 10,000,000 operating cycles typical, with electrical endurance at 200,000 cycles typical.
Compliance and documentation
The module carries a substance prohibitance date of 05/01/2012, indicating RoHS compliance from that date onward. No short-circuit protection is integrated — the upstream supply or motor starter must provide that. Approvals include IEC 61508 (SIL CL 3), EN ISO 13849-1 (Category 4), and EN 62061 (SIL Claim Limit 3). The design is for safety circuits per the product designation.