The Siemens 5SU1344-0KK82 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — rated 125 A at 400 V AC, 50 Hz, in a 4-pole (4P) configuration with a B tripping characteristic. Energy limiting class 3 means it restricts let-through energy during a short circuit, reducing stress on downstream components. The fault-current type is AC-sensitive — it detects sinusoidal residual currents. The unit is instantaneous (no intentional time delay), so it responds immediately to ground faults.
At 40 °C it derates to 115.62 A, at 45 °C to 111.25 A, at 50 °C to 106.25 A, at 55 °C to 101.25 A, and at 60 °C to 96.25 A.
Width is 198 mm (11 modular width units at 18 mm each), depth 77 mm, height 90 mm, with an installation depth of 70 mm. Mounting position is any orientation. Supply can enter from top or bottom — no mandatory orientation for the line side.
Compliance documentation includes RoHS and REACH declarations as standard for Siemens SENTRON products.