The 3RK1903-1BC00: A hardware fault tolerance of 1 (HFT = 1) means the module can tolerate a single fault and still maintain its safety function — a key requirement for SIL 3 subsystems. The PFHd value of 9E-9 1/h (probability of dangerous failure per hour) is well below the SIL 3 threshold of 10^-7, so this module is suitable for high-demand or continuous-operation safety functions like emergency stops, light curtain monitoring, or guard door interlocking on a conveyor or packaging line. The safe state is defined as the load circuit open, which is the standard fail-safe behavior for motor starter disconnection. The control supply voltage range is 20.4 to 28.8 V DC, which matches the standard 24 V DC industrial bus voltage with margin for ripple and drop. The module is Type B per IEC 61508-2, meaning it uses complex components (microprocessors, ASICs) and requires the diagnostic coverage that the 99% DCavg figure confirms is present.
Integration into the ET 200S system
This module snaps onto the TM-PF30 busbar at 30 mm width, extending fail-safe power distribution for ET 200S motor starters. It has bus communication capability.