The Siemens 5SU1353-1KV25 is a combined residual-current device and miniature circuit breaker (RCD/MCB combo), known as an FI/LS protector. The 30 mA sensitivity (IFN) provides supplementary protection against direct contact, while the C-curve 25 A overcurrent characteristic handles motor-starting inrush and moderate inductive loads without nuisance tripping.
The neutral pole is switched internally, so no separate neutral bar connection is needed downstream. In a panel with higher fault levels upstream, verify selectivity with the incoming MCCB.