The Siemens 3RV2811-0HD10 is a SIRIUS circuit breaker in size S00, designed specifically for transformer protection and compliant with UL 489 and CSA C22.2 No.5. It delivers 100 kA breaking capacity at 400 V AC — the same rating holds at 240 V, 500 V, and 690 V AC, so you get consistent fault-interrupt performance across common industrial voltages without derating the breaker.
The S00 footprint — 45 mm wide, 144 mm tall, 97 mm deep — fits standard sub-distribution boards and motor starter combos. Any mounting position works, which simplifies layout in tight enclosures.
Rated operational voltage spans 20 to 690 V, covering low-voltage control circuits through 690 V distribution. At 230 V it carries a 0.1 kW motor rating under AC-3 duty, so it's sized for small motor branches, not main feeders. The gG 6 A fuse backup at 690 V tells you the coordination curve: upstream fuse limits let-through energy for the breaker's own protection.
Main contact screws are M4; use a Pozidriv size 2 tip with a 5–6 mm shaft diameter. Strip and torque per standard practice — the spring-cage alternative isn't offered here.
Environmental limits
No ground-fault or phase-failure detection built in — those functions live in separate monitoring relays or the upstream protection.