RCBO for final-circuit protection
The Siemens 5SU1653-7KK32 is a SENTRON RCBO combining overcurrent and residual-current protection in a single 36 mm wide, 2-module unit. It's rated 32 A with a C-curve tripping characteristic — the standard choice for motor, lighting, and general-purpose final circuits where inrush currents are moderate. The Type A fault-current detection handles pulsating DC and AC residual currents, covering most commercial and industrial socket-outlet circuits. Breaking capacity is 4.5 kA per EN 60898, which suits domestic and light-commercial distribution boards where the prospective fault current stays under that threshold. The 1P+N configuration switches the phase only; the neutral is switched internally but not protected against overcurrent — typical for single-phase final circuits in TN or TT systems.
Ratings and what they mean for fit
The 32 A rating is derated across ambient temperature: 30.4 A at 40 °C, 28.8 A at 50 °C, down to 24.64 A at 70 °C. If your panel runs hot — say a packed enclosure near a motor drive — size the upstream protection for the derated value, not the 32 A label. The solid and stranded conductor range of 0.75 to 35 mm² covers everything from 1.5 mm² lighting circuits up to 10 mm² feeder tails; no adapter needed for the larger cross-sections. Energy limiting class 3 means it lets through less let-through energy (I²t) than class 2 or 1 devices, which helps with downstream coordination. The instantaneous design (no intentional time delay) trips within the standard C-curve window of 5× to 10× In — so 160 A to 320 A fault current clears in under 0.1 s.
Panel integration and mounting
Snaps onto standard 35 mm DIN rail, mounting position any. Depth is 77 mm (installation depth 70 mm), height 90 mm — fits most distribution boards without depth clearance issues. IP20 with the distribution board installed and conductors connected; not rated for wet or dusty environments without an enclosure. Supply can enter from top or bottom — no mandatory orientation. Power dissipation max 11.4 W at rated load, so factor that into your enclosure thermal budget if the board is densely populated. Halogen-free and silicon-free construction, relevant for clean-room or high-reliability installations where outgassing matters.