What it is and what it does
The Siemens SENTRON 5SU1353-1WM40 is a 1P+N RCBO (residual current circuit breaker with overcurrent protection) rated 40 A with a C tripping characteristic and 30 mA AC-type residual current sensitivity. It combines overcurrent and earth-fault protection in a single 2-module-width (36 mm) package, saving rail space in a DIN-rail distribution board. The 70 mm installation depth fits standard enclosures without crowding. Rated breaking capacity is 4.5 kA per EN 60898 for residential and commercial final circuits, and 10 kA per IEC 60947-2 for industrial applications where higher fault currents are expected. The C-curve (5–10× In) handles moderate inrush from motorized loads like pumps or compressors without nuisance tripping. The 30 mA AC-type residual current element protects against direct-contact faults and provides supplementary fire protection in circuits supplying socket outlets or portable equipment. It's rated for 50 Hz supply and accepts supply from either top or bottom, simplifying panel wiring.
Temperature range and environmental tolerance
Rated for ambient temperatures from -40 °C to 75 °C, covering outdoor enclosures in cold climates and warm cabinet interiors near transformers or drives. The wide span means no derating for most real-world panel conditions. Halogen-free and silicon-free construction reduces toxic smoke in a fire and avoids silicone outgassing that can contaminate relay contacts or optical sensors in shared enclosures. Pollution degree 2 (non-conductive pollution only) and overvoltage category III suit fixed installations downstream of the main distribution board.
Lifecycle and sourcing posture
Listed as current production (active lifecycle stage). The 5SU1353-1WM40 is a standard catalog item in the SENTRON RCBO family, not subject to phase-out or last-time-buy. Sourced and quoted to order through independent distribution; availability and current pricing confirmed at quote time against an RFQ.
Panel fit and integration notes
Mounts on 35 mm DIN rail per EN 60715 in any position. Two modular width units (36 mm) and 70 mm depth leave clearance for wiring and adjacent devices. IP20 rating applies when installed in a distribution board with conductors connected — standard for enclosed panel use. Touch-protected terminals reduce arc-flash risk during commissioning. Neutral conductor is switched internally (1P+N), so the device isolates both phase and neutral on fault. Supply cord position is flexible — top or bottom feed — which helps when retrofitting into an existing board with fixed busbar orientation.