Siemens SENTRON 5SU9326-1CR63 — RCBO, 63 A, 30 mA, Type AC
The Siemens SENTRON 5SU9326-1CR63 is a 2-pole residual-current-operated circuit breaker (RCBO) combining overcurrent and earth-fault protection in a single 4-module-width unit. Rated 63 A at 30 °C with a 30 mA residual-current trip and Type AC sensitivity, it handles sinusoidal AC fault currents in residential and commercial final circuits. The C characteristic (tripping curve) matches moderate inrush loads like small motors, pumps, and lighting banks — common in European distribution boards.
Breaking capacity and standards compliance
Rated 6 kA breaking capacity under both EN 60898 and IEC 60947-2, so it clears faults up to that level in a 50/60 Hz network. The insulation voltage (Ui) is 440 V, overvoltage category III, pollution degree 2 — standard for fixed-installation switchgear. Surge voltage resistance is 4 000 V, with a surge current withstand of 1 kA at 8/20 μS waveform. Energy limitation class 3 means it limits let-through energy in a fault, aiding downstream coordination.
Thermal derating — what the 63 A rating means in a warm panel
The 63 A rating is at 30 °C ambient. At 40 °C it derates to 58.6 A, at 45 °C to 56.1 A, at 50 °C to 54.8 A, and at 55 °C to 53.6 A. In a crowded enclosure with multiple RCBOs side by side, the real continuous current capability may be lower than the label suggests — factor the derating curve into your panel thermal analysis. Mounting position is any, which simplifies layout.
Physical fit and panel integration
Dimensions are 72 mm wide (4 modular width units), 90 mm tall, 77 mm deep with a 70 mm installation depth. The IP20 rating applies only when the distribution board is installed and conductors are connected — this is an open-back device, not for standalone use. Halogen-free and silicon-free construction, so it meets material restrictions for clean environments or green-building specs. Supply can enter from top or bottom; the test button requires a minimum 125 V to operate.