What it is and what it does
The Siemens SENTRON 5SM2623-6 is a 2-pole residual current device (RCD unit) rated 40 A, 300 mA fault current, Type A, for 230 V AC at 50 Hz. It is an instantaneous-trip design — no adjustable delay — intended for use with the 5SL4 series MCB to form an RCBO combination in a distribution board. The 2-module-width (2 MW) body, 70 mm deep, snaps onto DIN rail in any mounting position.
Key ratings and what they mean for fit
Rated at 40 A continuous and 300 mA residual trip threshold, Type A detects pulsating DC fault currents as well as sinusoidal AC — required on circuits feeding single-phase rectified loads (switch-mode supplies, variable-speed drives, LED drivers). The 230 V AC / 50 Hz supply voltage is fixed; the unit is not rated for 60 Hz or mixed-frequency networks. Insulation voltage (Ui) is 460 V, overvoltage category III, pollution degree 2 — suitable for fixed-installation distribution boards within a building's main or sub-distribution.
Installation and environmental limits
Mounts on DIN rail (REG fastening method) in any orientation. IP20 protection applies only when the distribution board is installed and conductors are connected — not a standalone outdoor rating. Ambient operating range -25 °C to +45 °C; storage range -40 °C to +75 °C. The 2 MW width (36 mm per module) occupies two adjacent slots in a standard 18 mm pitch enclosure. Sealable? No — the test button and reset are accessible without a seal cap.