The Siemens 5SU1656-7KV32 is an FI/LS-Protector (RCBO) Type A, combining overcurrent and residual-current protection in a single 1+N-pole unit. Rated at 32 A with a C-trip curve and a 300 mA residual sensitivity, it interrupts fault currents up to 6 kA. The 70 mm width fits standard Siemens distribution board cutouts.
What the ratings mean for fit
The C-curve (32 A) means the magnetic trip operates at 5–10× In, so it handles motor-start inrush and transformer energisation without nuisance tripping — typical for lighting, socket circuits, and small motor loads in commercial or residential panels. The 300 mA residual-current sensitivity (Type A) detects pulsating DC fault currents, which standard AC-only RCDs miss; this is required for circuits with single-phase rectifiers, switched-mode power supplies, or variable-speed drives. The 6 kA breaking capacity (Icn) is adequate for most domestic and light commercial installations where the prospective short-circuit current at the board is below that level.
Panel integration
The 70 mm module width (4.5 standard DIN modules) snaps onto a DIN rail in the distribution board. The 1+N-pole design switches the line conductor only; the neutral is switched internally for isolation but not protected against overcurrent. Terminals accept up to 25 mm² conductor — typical for sub-main or final subcircuit wiring.