What this 2-pole RC unit brings to the panel
The SENTRON 5SM9622-0KK is a 2-pole residual current unit (type AC) rated 40 A at 400 V AC, 50 Hz, with a 300 mA trip threshold. That 300 mA sensitivity is sized for equipment protection or fire-prevention circuits rather than personnel shock protection (which typically calls for 30 mA or lower). The type AC designation means it detects sinusoidal AC residual currents only — no pulsed DC or smooth DC component. If your load includes rectifiers, VFDs, or switched-mode supplies, you need a type A or type F unit instead. The 40 A rating holds at 40 °C ambient (37.2 A derated), then steps down through a published curve: 36 A at 50 °C, 34 A at 60 °C, and 32 A at 70 °C. That thermal derating is the spec to watch if the unit sits in a crowded enclosure or near heat-generating busbars — the headline 40 A only applies up to 40 °C.
Lifecycle and sourcing posture
Lifecycle stage is marked current — this is an active, in-production catalog line from Siemens SENTRON. No phase-out notice or last-time-buy date on record. For BOM-freeze or line-down replacement, the part is sourced to order against an RFQ through independent distribution; pricing and lead time confirmed at quote time.
Integration notes
Two-pole form factor snaps onto DIN rail in the standard SENTRON modular footprint. The RC unit is instantaneous-trip design — no intentional time delay, so it trips within one cycle on a fault. That makes it fast but means it coordinates poorly with downstream selective MCBs unless the fault current is well above the MCB's instantaneous threshold. Pair it with a time-delayed SENTRON RC unit upstream if selectivity is required.