It's a 3-pole unit designed for line protection — think main feeder or large branch circuit in a distribution panel. The breaking capacity at 240 V is 121 kA, dropping to 76 kA at 415 V and 53 kA at 440 V; at 500 V it's still 12 kA, so it handles industrial fault levels across common low-voltage systems. Thermal derating is gradual: it holds 32 A continuous from 40 °C through 50 °C, then steps down to 31 A at 55 °C and 60 °C, and 30 A at 65 °C and 70 °C. That means in a warm panel you lose only about 6% capacity at the top end — decent headroom for a 320 A frame.
That means it's still a standard catalog item from Siemens, so you can spec it into new builds without worrying about last-time-buy windows.
The 3-pole footprint fits standard Siemens SENTRON panel cutouts and busbar systems.
Approvals & Compliance
Rated insulation voltage is 800 V, and the operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. It's a straightforward, serviceable MCCB for standard line protection duty.