What it is and where it fits
The Siemens SIMATIC 3RK1903-0CB00 is a brake control module, 24 V DC nominal, supplying a 24 V DC brake. It is pluggable on a terminal module, meaning it snaps onto a prewired base without disturbing the existing wiring — a clean swap for a line-down situation. The 15 mm width and 95 mm depth keep it slim on the DIN rail; height is 196.5 mm. Mount vertically or horizontally.
Key ratings and what they mean for fit
Supply voltage is 24 V DC, permissible range 20.4 V to 28.8 V — so it holds on a nominal 24 V bus even with a moderate drop. Surge voltage resistance is 8 kV, which places it in severity 3 / industrial ambient A per IEC 60947-1. That means it can ride out the transients common on a motor-heavy line without nuisance failure. Shock resistance is 5g / 11 ms; vibration resistance is 2g — robust enough for most panel-mounted environments but not for direct machine-mount without isolation.
Integration notes
Main energy infeed uses screw-type terminals; load-side outgoing feeder also screw-type. Energy bus transmission is via the backplane bus — no separate power wiring needed for the bus. Two poles for the main current circuit. Brake control is 24 V DC only; no 180 V DC, 230 V AC, or 500 V DC brake control. Operating frequency up to 750 1/h. Ambient operating temperature 0 to 60 °C; storage and transport -40 to +70 °C. Relative humidity 5 to 95 % during operation. No PROFIenergy shutdown or measured values.