The Siemens 5SU1354-1RC10 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — rated 10 A with a 30 mA Type AC residual-current trip, C-curve, 2-pole (1P+N), in a 2-module (36 mm) housing. It is a current-production part, not a phase-out or obsolete line.
The 10 A rated current with C-curve tripping characteristic means the breaker holds 10 A continuously and trips magnetically between 5× and 10× rated current (50–100 A) — standard for motor and transformer inrush on a lighting or small-power final subcircuit. The 30 mA Type AC residual-current element detects sinusoidal AC earth faults only; if the downstream load includes VFDs, UPS, or switching power supplies that generate pulsed DC or high-frequency leakage, an A or F type RCBO would be the better choice. That 20 kA rating at 240 V AC means it can safely interrupt a fault up to 20,000 A without welding contacts or cascading upstream — sufficient for most distribution boards fed by a 200–400 kVA transformer.
Snap-on DIN-rail mount, 2-module width (36 mm), depth 70 mm, height 90 mm. IP20 rating applies only when the distribution board is closed and conductors are connected; this is a panel-interior device, not surface-mount or outdoor.